Disruption of the extensor mechanism in total knee arthroplasty may occur by tubercle avulsion, patellar or quadriceps tendon rupture, or patella fracture, and whether occurring intra-operatively or post-operatively can be difficult to manage and is associated with a significant rate of failure and associated complications. This surgery is frequently performed in compromised tissues, and repairs must frequently be protected with cerclage wiring and/or augmentation with local tendon (semi-tendinosis, gracilis) which may also be used to treat soft-tissue loss in the face of chronic disruption. Quadriceps rupture may be treated with conservative therapy if the patient retains active extension. Component loosening or loss of active extension of 20° or greater are clear indications for surgical treatment of patellar fracture. Acute patellar tendon disruption may be treated by primary repair. Chronic extensor failure is often complicated by tissue loss and retraction can be treated with medial gastrocnemius flaps, achilles tendon allografts, and complete extensor mechanism allografts. Attention to fixing the graft in full extension is mandatory to prevent severe extensor lag as the graft stretches out over time

We describe the influence of the angle of immobilisation during partial weight-bearing on the forces across the extensor mechanism of the knee. Gait analysis was performed on eight healthy male subjects with the right knee in an orthotic brace locked at 0°, 10°, 20° and 30°, with the brace unlocked and also without a brace. The ground reaction force, the angle of the knee and the net external flexion movement about the knee were measured and the extensor mechanism force was calculated. The results showed a direct non-linear relationship between the angle of knee flexion and the extensor mechanism force. When a brace was applied, the lowest forces occurred when the brace was locked at 0°. At 30° the forces approached the failure strength of some fixation devices. We recommend that for potentially unstable injuries of the extensor mechanism, when mobilising with partial weight-bearing, the knee should be flexed at no more than 10°

Anterior knee pain due to dysplasia of the extensor mechanism is common. We have studied 137 knees (103 patients) in order to identify a rapid and reproducible radiological feature which would indicate the need for further analysis. Overall, 67 knees (49%) had at least one radiological abnormality; 70 (51%) were considered normal. There were five cases of Dejour type-3 dysplasia of the femoral trochlea, nine of type-2 and 12 of type-1. There were 49 cases of patella alta and five of patella infera. Four knees had an abnormal lateral patellofemoral angle (patellar tilt), and in 15 knees there was more than one abnormality. Classification of trochlear dysplasia was difficult and showed poor reproducibility. This was also true for the measurement of the lateral patellofemoral angle. Patellar height was more easily measured but took time. The sulcus angle is an easily and rapidly measurable feature which was reproducible and was closely related to other features of dysplasia of the extensor mechanism. The finding of a normal sulcus angle suggested that seeking other radiological evidence of malalignment of the extensor mechanism was unlikely to reveal additional useful information. The severity of other features of dysplasia of the extensor mechanism correlated with increasing sulcus angle

We present the histological findings of an extensor mechanism allograft which was used in a total knee arthroplasty two years after implantation. Analysis of the graft was undertaken at four distinct anatomical levels and it was found to be incorporated into host tissue at each level. A wedge of fibrinoid necrosis, probably related to impingement of the graft on the tibial polyethylene insert, was seen. Impingement may play a role in the injury and necrosis of an allograft and may be one mode of failure in an extensor mechanism allograft

We developed an in vivo model of the attachment of a patellar tendon to a metal implant to simulate the reconstruction of an extensor mechanism after replacement of the proximal tibia. In 24 ewes, the patellar tendon was attached to a hydroxyapatite (HA)-coated titanium prosthesis. In 12, the interface was augmented with autograft containing cancellous bone and marrow. In the remaining ewes, the interface was not grafted. Kinematic gait analysis showed nearly normal function of the joint by 12 weeks. Force-plate assessment showed a significant increase in functional weight-bearing in the grafted animals (p = 0.043). The tendon-implant interface showed that without graft, encapsulation of fibrous tissue occurred. With autograft, a developing tendon-bone-HA-implant interface was observed at six weeks and by 12 weeks a layered tendon-fibrocartilage-bone interface was seen which was similar to a direct-type enthesis. With stable mechanical fixation, an appropriate bioactive surface and biological augmentation the development of a functional tendon-implant interface can be achieved

This study reports the clinical outcome of reconstruction of deficient abductor muscles following revision total hip arthroplasty (THA), using a fresh–frozen allograft of the extensor mechanism of the knee. A retrospective analysis was conducted of 11 consecutive patients with a severe limp because of abductor deficiency which was confirmed on MRI scans. The mean age of the patients (three men and eight women) was 66.7 years (52 to 84), with a mean follow-up of 33 months (24 to 41). . Following surgery, two patients had no limp, seven had a mild limp, and two had a persistent severe limp (p = 0.004). The mean power of the abductors improved on the Medical Research Council scale from 2.15 to 3.8 (p < 0.001). Pre-operatively, all patients required a stick or walking frame; post-operatively, four patients were able to walk without an aid. Overall, nine patients had severe or moderate pain pre-operatively; ten patients had no or mild pain post-operatively. . At final review, the Harris hip score was good in five patients, fair in two and poor in four. . We conclude that using an extensor mechanism allograft is relatively effective in the treatment of chronic abductor deficiency of the hip after THA when techniques such as local tissue transfer are not possible. . Longer-term follow-up is necessary before the technique can be broadly applied. Cite this article: Bone Joint J 2015;97-B:1050–5

Experience with thirty-eight Asian children and adolescents who presented with either stiffness of the knee, genu recurvatum, habitual dislocation of the patella or congenital lateral dislocation of the patella showed that all those disorders were manifestations of contracture of the extensor mechanism, which fell into two groups according to the components involved. In Group I the main components affected were in the midline of the limb, namely rectus femoris and vastus intermedius; these patients presented with varying degrees of stiffness of the knee, or worse, with genu recurvatum. In Group II the main components involved were lateral to the midline of the limb, namely vastus lateralis and the ilio-tibial band; these patients presented with habitual dislocation of the patella, or worse, congenital lateral dislocation of the patella. In both groups untreated patients developed secondary adaptive changes such as subluxation of the tibia or marked genu valgum which made operative procedures more formidable and less effective. Release of the contracture should therefore be performed as early as possible

The aim of this study was to analyse the gait pattern, muscle force and functional outcome of patients who had undergone replacement of the proximal tibia for tumour and alloplastic reconstruction of the extensor mechanism using the patellar-loop technique. Between February 1998 and December 2009, we carried out wide local excision of a primary sarcoma of the proximal tibia, proximal tibial replacement and reconstruction of the extensor mechanism using the patellar-loop technique in 18 patients. Of these, nine were available for evaluation after a mean of 11.6 years (0.5 to 21.6). The strength of the knee extensors was measured using an Isobex machine and gait analysis was undertaken in our gait assessment laboratory. Functional outcome was assessed using the American Knee Society (AKS) and Musculoskeletal Tumor Society (MSTS) scores. The gait pattern of the patients differed in ground contact time, flexion heel strike, maximal flexion loading response and total sagittal plane excursion. The mean maximum active flexion was 91° (30° to 110°). The overall mean extensor lag was 1° (0° to 5°). The mean extensor muscle strength was 25.8% (8.3% to 90.3%) of that in the non-operated leg (p < 0.001). The mean functional scores were 68.7% (43.4% to 83.3%) (MSTS) and 71.1 (30 to 90) (AKS functional score). In summary, the results show that reconstruction of the extensor mechanism using this technique gives good biomechanical and functional results. The patients’ gait pattern is close to normal, except for a somewhat stiff knee gait pattern. The strength of the extensor mechanism is reduced, but sufficient for walking. . Cite this article: Bone Joint J 2015;97-B:1063–9

We used an in vivo model to assess the use of an autogenous cancellous bone block and marrow graft for augmenting tendon reattachment to metallic implants. We hypothesised that augmentation of the tendon-implant interface with a bone block would enable retention of the graft on the implant surface, enhance biological integration, and result in more consistent functional outcomes compared with previously reported morcellised graft augmentation techniques.

A significant improvement in functional weight-bearing was observed between six and 12 weeks. The significant increase in ground reaction force through the operated limb between six and 12 weeks was greater than that reported previously with morcellised graft augmented reconstructions. Histological appearance and collagen fibre orientation with bone block augmentation more closely resembled that of an intact enthesis compared with the morcellised grafting technique. Bone block augmentation of tendon-implant interfaces results in more reliable functional and histological outcomes, with a return to pre-operative levels of weight-bearing by 24 weeks.

Aims. The proximal tibia (PT) is the anatomical site most frequently affected by primary bone tumours after the distal femur. Reconstruction of the PT remains challenging because of the poor soft-tissue cover and the need to reconstruct the extensor mechanism. Reconstructive techniques include implantation of massive endoprosthesis (megaprosthesis), osteoarticular allografts (OAs), or allograft-prosthesis composites (APCs). Methods. This was a retrospective analysis of clinical data relating to patients who underwent proximal tibial arthroplasty in our regional bone tumour centre from 2010 to 2018. Results. A total of 76 patients fulfilled the inclusion criteria and were included in the study. Mean age at surgery was 43.2 years (12 to 86 (SD 21)). The mean follow-up period was 60.1 months (5.4 to 353). In total 21 failures were identified, giving an overall failure rate of 27.6%. Prosthesis survival at five years was 75.5%, and at ten years was 59%. At last follow-up, mean knee flexion was 89.8° (SD 36°) with a mean extensor lag of 18.1° (SD 24°). In univariate analysis, factors associated with better survival of the prosthesis were a malignant or metastatic cancer diagnosis (versus benign), with a five- and ten-year survival of 78.9% and 65.7% versus 37.5% (p = 0.045), while in-hospital length of stay longer than nine days was also associated with better prognosis with five- and ten-year survival rates at 84% and 84% versus 60% and 16% (p < 0.001). In multivariate analysis, only in-hospital length of stay was associated with longer survival (hazard ratio (HR) 0.23, 95% confidence interval (CI) 0.08 to 0.66). Conclusion. We have shown that proximal tibial arthroplasty with endoprosthesis is a safe and reliable method for reconstruction in patients treated for orthopaedic oncological conditions. Either modular or custom implants in this series performed well. Cite this article: Bone Jt Open 2022;3(9):733–740

Aims

Unicompartmental knee arthroplasty (UKA) and bicompartmental knee arthroplasty (BCA) have been associated with improved functional outcomes compared to total knee arthroplasty (TKA) in suitable patients, although the reason is poorly understood. The aim of this study was to measure how the different arthroplasties affect knee extensor function.

Bicondylar tibial plateau fractures result from high-energy injuries. Fractures of the tibial plateau can involve the tibial tubercle, which represents a disruption to the extensor mechanism and logically must be stabilised. The purpose of this study was to identify the incidence of an independent tibial tubercle fracture in bicondylar tibial plateau fractures, and to report management strategies and potential complications. We retrospectively reviewed a prospectively collected orthopaedic trauma database for the period January 2003 to December 2008, and identified 392 bicondylar fractures of the tibial plateau, in which 85 tibial tubercle fractures (21.6%) were identified in 84 patients. There were 60 men and 24 women in our study group, with a mean age of 45.4 years (18 to 71). In 84 fractures open reduction and internal fixation was undertaken, either with screws alone (23 patients) or with a plate and screws (61 patients). The remaining patient was treated non-operatively. In all, 52 fractures were available for clinical and radiological assessment at a mean follow-up of 58.5 weeks (24 to 94). All fractures of the tibial tubercle united, but 24 of 54 fractures (46%) required a secondary procedure for their tibial plateau fracture. Four patients reported pain arising from prominent tubercle plates and screws, which in one patient required removal. Tibial tubercle fractures occurred in over one-fifth of the bicondylar tibial plateau fractures in our series. Fixation is necessary and can be reliably performed with screws alone or with a screw and plate, which restores the extensor mechanism and facilitates early knee flexion.

Cite this article: Bone Joint J 2013;95-B:1697–1702.

Aims. Tibial tubercle osteotomy (TTO) facilitates surgical exposure and protects the extensor mechanism during revision total knee arthroplasty (rTKA). The purpose of this study was to determine the rates of bony union, complications, and reoperations following TTO during rTKA, to assess the functional outcomes of rTKA with TTO at two years’ minimum follow-up, and to identify the risk factors of failure. Methods. Between January 2010 and September 2020, 695 rTKAs were performed and data were entered into a prospective database. Inclusion criteria were rTKAs with concomitant TTO, without extensor mechanism allograft, and a minimum of two years’ follow-up. A total of 135 rTKAs were included, with a mean age of 65 years (SD 9.0) and a mean BMI of 29.8 kg/m. 2. (SD 5.7). The most frequent indications for revision were infection (50%; 68/135), aseptic loosening (25%; 34/135), and stiffness (13%; 18/135). Patients had standardized follow-up at six weeks, three months, six months, and annually thereafter. Complications and revisions were evaluated at the last follow-up. Functional outcomes were assessed using the Knee Society Score (KSS) and range of motion. Results. The mean follow-up was 51 months (SD 26; 24 to 121). Bony union was confirmed in 95% of patients (128/135) at a mean of 3.4 months (SD 2.7). The complication rate was 15% (20/135), consisting of nine tibial tubercle fracture displacements (6.7%), seven nonunions (5%), two delayed unions, one tibial fracture, and one wound dehiscence. Seven patients (5%) required eight revision procedures (6%): three bone grafts, three osteosyntheses, one extensor mechanism allograft, and one wound revision. The functional scores and flexion were significantly improved after surgery: mean KSS knee, 48.8 (SD 17) vs 79.6 (SD 20; p < 0.001); mean KSS function, 37.6 (SD 21) vs 70.2 (SD 30; p < 0.001); mean flexion, 81.5° (SD 33°) vs 93° (SD 29°; p = 0.004). Overall, 98% of patients (n = 132) had no extension deficit. The use of hinge implants was a significant risk factor for tibial tubercle fracture (p = 0.011). Conclusion. TTO during rTKA was an efficient procedure to improve knee exposure with a high union rate, but had significant specific complications. Functional outcomes were improved at mid term. Cite this article: Bone Joint J 2023;105-B(10):1078–1085

Recognized anatomic variations that lead to patella instability include patella alta and trochlea dysplasia. Lateralization of the extensor mechanism relative to the trochlea is often considered to be a contributing factor; however, controversy remains as to the degree this contributes to instability and how this should be measured. As the tibial tuberosity-trochlear groove (TT-TG) is one of most common imaging measurements to assess lateralization of the extensor mechanism, it is important to understand its strengths and weaknesses. Care needs to be taken while interpreting the TT-TG value as it is affected by many factors. Medializing tibial tubercle osteotomy is sometimes used to correct the TT-TG, but may not truly address the underlying anatomical problem. This review set out to determine whether the TT-TG distance sufficiently summarizes the pathoanatomy, and if this assists with planning of surgery in patellar instability. Cite this article: Bone Jt Open 2022;3(3):268–274

The October 2023 Sports Roundup. 360. looks at: Extensor mechanism disruption in the treatment of dislocated and multiligament knee injuries; Treatment of knee osteoarthritis with injection of stem cells; Corticosteroid injection plus exercise or exercise alone as adjuvants for patients with plantar fasciitis?; Generalized joint hypermobility and a second ACL injury?; The VISA-A ((sedentary) questionnaire for Achilles tendinopathy?

Periprosthetic joint infection represents a devastating complication after total elbow arthroplasty. Several measures can be implemented before, during, and after surgery to decrease infection rates, which exceed 5%. Debridement with antibiotics and implant retention has been reported to be successful in less than one-third of acute infections, but still plays a role. For elbows with well-fixed implants, staged retention seems to be equally successful as the more commonly performed two-stage reimplantation, both with a success rate of 70% to 80%. Permanent resection or even amputation are occasionally considered. Not uncommonly, a second-stage reimplantation requires complex reconstruction of the skeleton with allografts, and the extensor mechanism may also be deficient. Further developments are needed to improve our management of infection after elbow arthroplasty. Cite this article: Bone Joint J 2024;106-B(11):1321–1326

Aims. Periprosthetic joint infection (PJI) is a devastating complication following total knee arthroplasty (TKA). Two-stage revision has traditionally been considered the gold standard of treatment for established infection, but increasing evidence is emerging in support of one-stage exchange for selected patients. The objective of this study was to determine the outcomes of single-stage revision TKA for PJI, with mid-term follow-up. Methods. A total of 84 patients, with a mean age of 68 years (36 to 92), underwent single-stage revision TKA for confirmed PJI at a single institution between 2006 and 2016. In all, 37 patients (44%) were treated for an infected primary TKA, while the majority presented with infected revisions: 31 had undergone one previous revision (36.9%) and 16 had multiple prior revisions (19.1%). Contraindications to single-stage exchange included systemic sepsis, extensive bone or soft-tissue loss, extensor mechanism failure, or if primary wound closure was unlikely to be achievable. Patients were not excluded for culture-negative PJI or the presence of a sinus. Results. Overall, 76 patients (90.5%) were infection-free at a mean follow-up of seven years, with eight reinfections (9.5%). Culture-negative PJI was not associated with a higher reinfection rate (p = 0.343). However, there was a significantly higher rate of recurrence in patients with polymicrobial infections (p = 0.003). The mean Oxford Knee Score (OKS) improved from 18.7 (SD 8.7) preoperatively to 33.8 (SD 9.7) at six months postoperatively (p < 0.001). The Kaplan-Meier implant survival rate for all causes of reoperation, including reinfection and aseptic failure, was 95.2% at one year (95% confidence interval (CI) 87.7 to 98.2), 83.5% at five years (95% CI 73.2 to 90.3), and 78.9% at 12 years (95% CI 66.8 to 87.2). Conclusion. One-stage exchange, using a strict debridement protocol and multidisciplinary input, is an effective treatment option for the infected TKA. This is the largest single-surgeon series of consecutive cases reported to date, with broad inclusion criteria. Cite this article: Bone Jt Open 2021;2(5):305–313

Aims. To describe the risk of periprosthetic joint infection (PJI) and reoperation in patients who have an acute, traumatic wound dehiscence following total knee arthroplasty (TKA). Methods. From January 2002 to December 2018, 16,134 primary TKAs were performed at a single institution. A total of 26 patients (0.1%) had a traumatic wound dehiscence within the first 30 days. Mean age was 68 years (44 to 87), 38% (n = 10) were female, and mean BMI was 34 kg/m. 2. (23 to 48). Median time to dehiscence was 13 days (interquartile range (IQR) 4 to 15). The dehiscence resulted from a fall in 22 patients and sudden flexion after staple removal in four. The arthrotomy was also disrupted in 58% (n = 15), including a complete extensor mechanism disruption in four knees. An irrigation and debridement with component retention (IDCR) was performed within 48 hours in 19 of 26 knees and two-thirds were discharged on antibiotic therapy. The mean follow-up was six years (2 to 15). The association of wound dehiscence and the risk of developing a PJI was analyzed. Results. Patients who sustained a traumatic wound dehiscence had a 6.5-fold increase in the risk of PJI (95% confidence interval (CI) 1.6 to 26.2; p = 0.008). With the small number of PJIs, no variables were found to be significant risk factors. However, there were no PJIs in any of the patients who were treated with IDCR and a course of antibiotics. Three knees required reoperation including one two-stage exchange for PJI, one repeat IDCR for PJI, and one revision for aseptic loosening of the tibial component. Conclusion. Despite having a traumatic wound dehiscence, the risk of PJI was low, but much higher than experienced in all other TKAs during the same period. We recommend urgent IDCR and a course of postoperative antibiotics to decrease the risk of PJI. A traumatic wound dehiscence increases risk of PJI by 6.5-fold. Cite this article: Bone Joint J 2021;103-B(6 Supple A):191–195

Aims. This study aimed to determine outcomes of isolated tibial insert exchange (ITIE) during revision total knee arthroplasty (TKA). Methods. From 1985 to 2016, 270 ITIEs were performed at one institution for instability (55%, n = 148), polyethylene wear (39%, n = 105), insert fracture/dissociation (5%, n = 14), or stiffness (1%, n = 3). Patients with component loosening, implant malposition, infection, and extensor mechanism problems were excluded. Results. Survivorship free of any re-revision was 68% at ten years. For the indication of insert wear, survivorship free of any re-revision at ten years was 74%. Re-revisions were more frequent for index diagnoses other than wear (hazard ratio (HR) 1.9; p = 0.013), with ten-year survivorships of 69% for instability and 37% for insert fracture/dissociation. Following ITIE for wear, the most common reason for re-revision was aseptic loosening (33%, n = 7). For other indications, the most common reason for re-revision was recurrence of the original diagnosis. Mean Knee Society Scores improved from 54 (0 to 94) preoperatively to 77 (38 to 94) at ten years. Conclusion. After ITIE, the risk and reasons for re-revision correlated with preoperative indications. The best results were for polyethylene wear. For other diagnoses, the re-revision rate was higher and the failure mode was most commonly recurrence of the original indication for the revision TKA. Cite this article: Bone Joint J 2021;103-B(6):1103–1110

We reviewed the records of 107 consecutive patients who had undergone surgery for disruption of the knee extensor mechanism to test whether an association existed between rupture of the quadriceps tendon and the presence of a patellar spur. The available standard pre-operative lateral radiographs were examined to see if a patellar spur was an indicator for rupture of the quadriceps tendon in this group of patients. Of the 107 patients, 12 underwent repair of a ruptured patellar tendon, 59 had an open reduction and internal fixation of a patellar fracture and 36 repair of a ruptured quadriceps tendon. In the 88 available lateral radiographs, patellar spurs were present significantly more commonly (p < 0.0005) in patients operated on for rupture of the quadriceps tendon (79%) than in patients with rupture of the patellar tendon (27%) or fracture of the patella (15%). In patients presenting with failure of the extensor mechanism of the knee in the presence of a patellar spur, rupture of the quadriceps tendon should be considered as a possible diagnosis

Aims. The integrity of the soft tissue envelope is crucial for successful treatment of infected total knee arthroplasty (TKA). The purpose of this study was to evaluate the rate of limb salvage, infection control, and clinical function following microvascular free flap coverage for salvage of the infected TKA. Methods. We retrospectively reviewed 23 microvascular free tissue transfers for management of soft tissue defects in infected TKA. There were 16 men and seven women with a mean age of 61.2 years (39 to 81). The median number of procedures performed prior to soft tissue coverage was five (2 to 9) and all patients had failed at least one two-stage reimplantation procedure. Clinical outcomes were measured using the Knee Society Scoring system for pain and function. Results. In all, one patient was lost to follow-up prior to 12 months. The remaining 22 patients were followed for a mean of 46 months (12 to 92). At latest follow-up, four patients (18%) had undergone amputation for failure of treatment and persistent infection. For the other 18 patients, 11 patients (50%) had maintained a knee prosthesis in place while seven patients had undergone resections for persistent infection but retained their limbs (32%). Reoperations were common following coverage and reimplantation. The median number of additional procedures was two (0 to 6). Clinical function was poor in patients who underwent reimplantation and retained a knee prosthesis following free flap coverage with a mean KSS score for pain and function of 44 (0 to 70) and 30 (0 to 65), respectively. All patients required an assistive device. Extensor mechanism problems and extensor lag requiring bracing were common following limb salvage and prosthesis reimplantation. Conclusion. Microvascular tissue transfer for management of infected TKA can be successful in limb salvage (82%) but clinical outcomes in salvaged limbs were poor. Cite this article: Bone Joint J 2020;102-B(6 Supple A):176–180

Aims. Arthrodesis is rarely used as a salvage procedure for patients with a chronically infected total knee arthroplasty (TKA), and little information is available about the outcome. The aim of this study was to assess the reliability, durability, and safety of this procedure as the definitive treatment for complex, chronically infected TKA, in a current series of patients. Methods. We retrospectively identified 41 patients (41 TKAs) with a complex infected TKA, who were treated between 2002 and 2016 using a deliberate, two-stage knee arthrodesis. Their mean age was 64 years (34 to 88) and their mean body mass index (BMI) was 39 kg/m. 2. (25 to 79). The mean follow-up was four years (2 to 9). The extensor mechanism (EM) was deficient in 27 patients (66%) and flap cover was required in 14 (34%). Most patients were host grade B (56%) or C (29%), and limb grade 3 (71%), according to the classification of McPherson et al. A total of 12 patients (29%) had polymicrobial infections and 20 (49%) had multi-drug resistant organisms; fixation involved an intramedullary nail in 25 (61%), an external fixator in ten (24%), and dual plates in six (15%). Results. Survivorship free from amputation, persistent infection, and reoperation, other than removal of an external fixator, at five years was 95% (95% confidence interval (CI) 89% to 100%), 85% (95% CI 75% to 95%), and 64% (95% CI 46% to 82%), respectively. Reoperation, other than removal of an external fixator, occurred in 13 patients (32%). After the initial treatment, radiological nonunion developed in ten knees (24%). Nonunion was significantly correlated with persistent infection (p = 0.006) and external fixation (p = 0.005). Of those patients who achieved limb salvage, 34 (87%) remained mobile and 31 (79%) had ‘absent’ or ‘minimal’ pain ratings. Conclusion. Knee arthrodesis using a two-stage protocol achieved a survivorship free from amputation for persistent infection of 95% at five years with 87% of patients were mobile at final follow-up. However, early reoperation was common (32%). This is not surprising as this series included worst-case infected TKAs in which two-thirds of the patients had a disrupted EM, one-third required flap cover, and most had polymicrobial or multi-drug resistant organisms. Cite this article: Bone Joint J 2020;102-B(6 Supple A):170–175

Aims. Bi-unicondylar arthroplasty (Bi-UKA) is a bone and anterior cruciate ligament (ACL)-preserving alternative to total knee arthroplasty (TKA) when the patellofemoral joint is preserved. The aim of this study is to investigate the clinical outcomes and biomechanics of Bi-UKA. Methods. Bi-UKA subjects (n = 22) were measured on an instrumented treadmill, using standard gait metrics, at top walking speeds. Age-, sex-, and BMI-matched healthy (n = 24) and primary TKA (n = 22) subjects formed control groups. TKA subjects with preoperative patellofemoral or tricompartmental arthritis or ACL dysfunction were excluded. The Oxford Knee Score (OKS) and EuroQol five-dimension questionnaire (EQ-5D) were compared. Bi-UKA, then TKA, were performed on eight fresh frozen cadaveric knees, to investigate knee extensor efficiency under controlled laboratory conditions, using a repeated measures study design. Results. Bi-UKA walked 20% faster than TKA (Bi-UKA mean top walking speed 6.7 km/h (SD 0.9),TKA 5.6 km/h (SD 0.7), p < 0.001), exhibiting nearer-normal vertical ground reaction forces in maximum weight acceptance and mid-stance, with longer step and stride lengths compared to TKA (p < 0.048). Bi-UKA subjects reported higher OKS (p = 0.004) and EQ-5D (p < 0.001). In vitro, Bi-UKA generated the same extensor moment as native knees at low flexion angles, while reduced extensor moment was measured following TKA (p < 0.003). Conversely, at higher flexion angles, the extensor moment of TKA was normal. Over the full range, the extensor mechanism was more efficient following Bi-UKA than TKA (p < 0.028). Conclusion. Bi-UKA had more normal gait characteristics and improved patient-reported outcomes, compared to matched TKA subjects. This can, in part, be explained by differences in extensor efficiency. Cite this article: Bone Joint Res 2021;10(11):723–733

Treatment of an infected total elbow replacement (TER) is often successful in eradicating or suppressing the infection. However, the extensor mechanism may be compromised by both the infection and the surgery. The goal of this study was to assess triceps function in patients treated for deep infection complicating a TER. Between 1976 and 2007 a total of 217 TERs in 207 patients were treated for infection of a TER at our institution. Superficial infections and those that underwent resection arthroplasty were excluded, leaving 93 TERs. Triceps function was assessed by examination and a questionnaire. Outcome was measured using the Mayo Elbow Performance Score (MEPS). Triceps weakness was identified in 51 TERs (49 patients, 55%). At a mean follow-up of five years (0.8 to 34), the extensor mechanism was intact in 13 patients, with the remaining 38 having bone or soft-tissue loss. The mean MEPS was 70 points (5 to 100), with a mean functional score of 18 (0 to 25) of a possible 25 points. Infection following TER can often be eradicated; however, triceps weakness occurs in more than half of the patients and may represent a major functional problem. Cite this article: Bone Joint J 2014;96-B:82–7

The February 2013 Trauma Roundup. 360 . looks at: the risk of ankle fractures; absorbable implants; minimally invasive heel fracture fixation; pertrochanteric fractures; arthroplasty and intracapsular hip fractures; and extensor mechanism disruption

We used demineralised bone matrix (DBM) to augment re-attachment of tendon to a metal prosthesis in an in vivo ovine model of reconstruction of the extensor mechanism at the knee. We hypothesised that augmentation of the tendon-implant interface with DBM would enhance the functional and histological outcomes as compared with previously reported control reconstructions without DBM. Function was assessed at six and 12 weeks postoperatively, and histological examination was undertaken at 12 weeks. A significant increase of 23.5% was observed in functional weight-bearing at six weeks in the DBM-augmented group compared with non-augmented controls (p = 0.004). By 12 weeks augmentation with DBM resulted in regeneration of a more direct-type enthesis, with regions of fibrocartilage, mineralised fibrocartilage and bone. In the controls the interface was predominantly indirect, with the tendon attached to the bone graft-hydroxyapatite base plate by perforating collagen fibres

Peri-prosthetic patellar fracture following resurfacing as part of total knee replacement (TKR) is an infrequent yet challenging complication. This case-control study was performed to identify clinical, radiological and surgical factors that increase the risk of developing a spontaneous patellar fracture after TKR. Patellar fractures were identified in 74 patients (88 knees) from a series of 7866 consecutive TKRs conducted between 1998 and 2009. After excluding those with a previous history of extensor mechanism realignment or a clear traumatic event, a metal-backed patella, any uncemented component or subsequent infection, the remaining 64 fractures were compared with a matched group of TKRs with an excellent outcome defined by the Knee Society score. The mean age of patients with a fracture was 70 years (51 to 81) at the time of TKR. Patellar fractures were detected at a mean of 13.4 months (2 to 84) after surgery. The incidence of patellar fracture was found to be strongly associated with the number of previous knee operations, greater pre-operative mechanical malalignment, smaller post-operative patellar tendon length, thinner post-resection patellar thickness, and a lower post-operative Insall-Salvati ratio. An understanding of the risk factors associated with spontaneous patellar fracture following TKR provides a valuable insight into prevention of this challenging complication

Between 1987 and 2006 we performed a modified Thompson’s quadricepsplasty on 40 fracture-related stiff knees and followed the patients for a mean of 7.9 years (2 to 11.1). The factors affecting the final gain of movement were investigated. A total of 15 knees required lengthening of the rectus femoris. The mean flexion gain was 70.2° (42.3° to 112.5°). According to Judet’s criteria, the results were excellent in 30 knees, good in seven, and fair in three. The range of movement which was achieved intra-operatively was related to the gain of knee flexion on univariate analysis. Five patients had complications: deep infection in one, recurrent patellar dislocation in one, and rupture of the extensor mechanism in three. This modified technique gives satisfactory results. Achieving maximum knee flexion intra-operatively seems to be the most important factor in enhancing the outcome in patients with stiffness of the knee following fracture

The Oxford medial unicompartmental knee replacement was designed to reproduce normal mobility and forces in the knee, but its detailed effect on the patellofemoral joint has not been studied previously. We have examined the effect on patellofemoral mechanics of the knee by simultaneously measuring patellofemoral kinematics and forces in 11 cadaver knee specimens in a supine leg-extension rig. Comparison was made between the intact normal knee and sequential unicompartmental and total knee replacement. Following medial mobile-bearing unicompartmental replacement in 11 knees, patellofemoral kinematics and forces did not change significantly from those in the intact knee across any measured parameter. In contrast, following posterior cruciate ligament retaining total knee replacement in eight knees, there were significant changes in patellofemoral movement and forces. The Oxford device appears to produce near-normal patellofemoral mechanics, which may partly explain the low incidence of complications with the extensor mechanism associated with clinical use

We reviewed 25 patients in whom a MUTARS megaprosthesis with a conical fluted stem had been implanted. There were three types of stem: a standard stem was used in 17 cases (three in the proximal femur, nine in the distal femur and five proximal tibia), a custom-made proximal femoral stem in four cases and a custom-made distal femoral stem in four cases. The mean age of the patients was 40.1 years (17 to 70) and the mean follow-up was for 2.5 years (0.9 to 7.4). At follow-up two patients had died from their disease: one was alive with disease and 22 were disease-free. One of 23 prostheses had been removed for infection and another revised to a cemented stem. The mean Musculoskeletal Tumor Society score was 24.9 (12 to 30) and the mean Karnofsky index was 82% (60% to 100%). There was no radiological evidence of loosening or subsidence. Stem stress shielding was seen in 11 patients and was marked in five of these. There were five complications, rupture of the extensor mechanism of the knee after extra-articular resection in two patients, deep venous thrombosis in one, septic loosening in one, and dislocation of the hip in one. The survival rate after seven years was 87% (95% confidence interval (CI) 83 to 91) for the patients and 95% (95% CI 91 to 99) for the megaprosthesis. A longer follow-up is needed to confirm these encouraging results

An abnormal lateral position of the tibial tuberosity causes distal malalignment of the extensor mechanism of the knee and can lead to lateral tracking of the patella causing anterior knee pain or objective patellar instability, characterised by recurrent dislocation. Computer tomography is used for a precise pre-operative assessment of the tibial tubercle-trochlear groove distance. A distance of more than 15 mm is considered to be pathological and an indication for surgery in symptomatic patients. In a prospective study we performed a subtle transfer of the tibial tuberosity according to the information gained from the pre-operative CT scan. This method was applied to two groups of patients, those with painful lateral tracking of the patella, and those with objective patellar instability. We evaluated the clinical results in 30 patients in each group. The outcome was documented at 3, 12 and 24 months using the Lysholm scale, the Kujala score, and a visual analogue pain score. Post-operatively, all but one patient in the instability group who had a patellar dislocation requiring further surgery reported good improvement with no further subluxation or dislocation. All patients in both groups had a marked improvement in pain and functional score. Two patients sustained a tibial fracture six and seven weeks after surgery. One patient suffered a per-operative fracture of the tibial tubercle which later required further fixation. If carefully performed, this type of transfer of the tibial tubercle appears to be a satisfactory technique for the treatment of patients with an increased tibial tubercle-trochlear groove distance and who present with symptoms related to lateral maltracking of the patella

This annotation reviews current concepts on the three most common surgical approaches used for proximal interphalangeal joint arthroplasty: dorsal, volar, and lateral. Advantages and disadvantages of each are highlighted, and the outcomes are discussed.

Cite this article: Bone Joint J 2022;104-B(12):1329–1333.

Aims

Obtaining solid implant fixation is crucial in revision total knee arthroplasty (rTKA) to avoid aseptic loosening, a major reason for re-revision. This study aims to validate a novel grading system that quantifies implant fixation across three anatomical zones (epiphysis, metaphysis, diaphysis).

Aims

Delayed postoperative inoculation of orthopaedic implants with persistent wound drainage or bacterial seeding of a haematoma can result in periprosthetic joint infection (PJI). The aim of this in vivo study was to compare the efficacy of vancomycin powder with vancomycin-eluting calcium sulphate beads in preventing PJI due to delayed inoculation.

Aims

Revision total knee arthroplasty (rTKA) is a technically challenging and costly procedure. It is well-documented that primary TKA (pTKA) have better survivorship than rTKA; however, we were unable to identify any studies explicitly investigating previous rTKA as a risk factor for failure following rTKA. The purpose of this study is to compare the outcomes following rTKA between patients undergoing index rTKA and those who had been previously revised.

Aims

In cases of severe periprosthetic joint infection (PJI) of the knee, salvage procedures such as knee arthrodesis (KA) or above-knee amputation (AKA) must be considered. As both treatments result in limitations in quality of life (QoL), we aimed to compare outcomes and factors influencing complication rates, mortality, and mobility.

Aims

The aim of this study was to evaluate medium- to long-term outcomes and complications of the Stanmore Modular Individualised Lower Extremity System (SMILES) rotating hinge implant in revision total knee arthroplasty (rTKA) at a tertiary unit. It is hypothesized that this fully cemented construct leads to satisfactory clinical outcomes.

Aims

Unicompartmental knee arthroplasty (UKA) has higher revision rates than total knee arthroplasty (TKA). As revision of UKA may be less technically demanding than revision TKA, UKA patients with poor functional outcomes may be more likely to be offered revision than TKA patients with similar outcomes. The aim of this study was to compare clinical thresholds for revisions between TKA and UKA using revision incidence and patient-reported outcomes, in a large, matched cohort at early, mid-, and late-term follow-up.

Aims

This multicentre retrospective observational study’s aims were to investigate whether there are differences in the occurrence of radiolucent lines (RLLs) following total knee arthroplasty (TKA) between the conventional Attune baseplate and its successor, the novel Attune S+, independent from other potentially influencing factors; and whether tibial baseplate design and presence of RLLs are associated with differing risk of revision.

Aims

This systematic review and meta-analysis aimed to compare the influence of patellar resurfacing following cruciate-retaining (CR) and posterior-stabilized (PS) total knee arthroplasty (TKA) on the incidence of anterior knee pain, knee-specific patient-reported outcome measures, complication rates, and reoperation rates.

We present a case of superior dislocation of the patella trapped by interlocked osteophytes. Unlike previous reports, in which the mechanism resulted from a blow to the inferior pole, it is postulated that increased load on the extensor mechanism, combined with patella alta and patellofemoral osteophytes, caused locking of the knee in extension

A case of duplication of the patella in the coronal plane is reported. Previously reported cases of double patella have shown sagittal or vertical duplication, and some have been associated with multiple epiphyseal dysplasia. In our case, excision of one patella and realignment of the extensor mechanism relieved symptoms of giving-way

1. Four cases of congenital lateral dislocation of the patella are described. 2. The significance of the associated flexion contracture is emphasised. 3. Early diagnosis and operative realignment of the extensor mechanism is considered to be important because it should avoid the secondary growth changes which can produce serious disability

We describe a U-shaped approach to the distal femur which, having divided the extensor mechanism and elevated the entire quadriceps muscle, gives excellent exposure and allows a number of reconstructive options. It was used in 14 patients, 13 of whom were followed up for a mean of 3.5 years (1 to 11). There was no case of flap necrosis, and complications related to the reconstruction were acceptable

Total knee replacements were performed on three patients with Parkinson's disease. The rehabilitation of all three was, however, hampered by inhibition of the extensor mechanism, hamstring rigidity and poor muscular co-ordination. Medical treatment of the disease did not help. None of the patients became mobile, and all three gradually weakened and died. We suggest that, at least in some patients with Parkinson's disease, knee replacement is contra-indicated

1. Rotational deformity of a finger caused by malunion of a phalangeal fracture has been corrected by metacarpal osteotomy. 2. Because of the anatomical arrangement of the metacarpo-phalangeal joint this method gives good control of the distal phalanges. 3. Division through the metacarpal rather than through the phalanx avoids adhesions in the flexor and extensor mechanisms and in the joints of the fingers, allows early mobilisation and is an easier procedure

A consecutive series of patients with a hydroxyapatite-coated uncemented total knee replacement (TKR) performed by a single surgeon between 1992 and 1995 was analysed. All patients were invited for clinical review and radiological assessment. Revision for aseptic loosening was the primary outcome. Assessment was based on the Knee Society clinical score (KSS) and an independent radiological analysis. Of 471 TKRs performed in 356 patients, 432 TKRs in 325 patients were followed for a mean of 16.4 years (15 to 18). The 39 TKRs in 31 patients lost to follow-up had a mean KSS of 176 (148 to 198) at a mean of ten years. There were revisions in 26 TKRs (5.5%), of which 11 (2.3%) were for aseptic loosening. Other further surgery was carried out on 49 TKRs (10.4%) including patellar resurfacing in 20, arthrolysis in 19, manipulation under anaesthetic in nine and extensor mechanism reconstruction in one. Survivorship at up to 18 years without aseptic loosening was 96% (95% confidence interval 91.9 to 98.1), at which point the mean KSS was 176 (134 to 200). Of 110 knees that underwent radiological evaluation, osteolysis was observed in five (4.5%), one of which was revised. These data indicate that uncemented hydroxyapatite-coated TKR can achieve favourable long-term survivorship, at least as good as that of cemented designs

Aims

During total knee replacement (TKR), surgeons can choose whether or not to resurface the patella, with advantages and disadvantages of each approach. Recently, the National Institute for Health and Care Excellence (NICE) recommended always resurfacing the patella, rather than never doing so. NICE found insufficient evidence on selective resurfacing (surgeon’s decision based on intraoperative findings and symptoms) to make recommendations. If effective, selective resurfacing could result in optimal individualized patient care. This protocol describes a randomized controlled trial to evaluate the clinical and cost-effectiveness of primary TKR with always patellar resurfacing compared to selective patellar resurfacing.

An electromyographic investigation of patients with subluxation of the patella has been carried out on the parts of the extensor apparatus which actively contribute to the alignment of the patella, both before and after the operation to correct this disorder. The electromyographic pictures have revealed a sharp fall in the activity of the vastus medialis, with full recovery to normal values after a corrective operation. Even if the aligning function of the patella is altered by a variety of factors, the present study confirms the importance of the vastus medialis in the pathogenesis of malalignment of the extensor mechanism