Genu recurvatum deformity is uncommon in arthritic knees undergoing total knee arthroplasty (TKA). We retrospectively analysed radiographs and navigation data to determine the clinical and radiographic results of computer-assisted TKA in knee arthritis with recurvatum deformity. Based on alignment data obtained during computer assisted (CAS) TKA, 40 arthritic knees (36 patients) with a recurvatum deformity of at least 5° were identified. The mean recurvatum deformity was 8.7° (6° to 14°). On preoperative standing hip-ankle radiographs, 23 limbs (57.5%) had a mean varus deformity of 169.4° (153° to 178°) and 17 limbs had a mean valgus deformity of 189.2° (182° to 224°). The intraoperative navigation data showed mean tibial resection of 7.5mm (4.6 to 13.4mm) and distal femur resection of 7.5mm (3.3 to 13mm) with a mean final extension gap of 21.2mm and a flexion gap at 90° of 21.1mm and on extension. On table, the mean knee deformity in sagittal plane was 3° flexion (1.5° to 4.5° flexion). Postoperatively, the mean HKA angle on standing hip-ankle radiographs was 179.2° (177° to 182°). On postoperative lateral radiographs, joint line in extension was moved distally in 35 limbs by 2.3mm (0.3 to 4mm) and proximally in 5 limbs by 2.2mm (2.2 to 2.4mm); the mean preoperative posterior femoral offset of 28.7 mm changed to 27.9 mm postoperatively. At a mean follow up 28 months (14- 48 months) the knee, function, and pain scores improved by 61, 48, and 28 points, respectively and there was no recurrence of recurvatum deformity at final follow up. Genu recurvatum is a notoriously difficult condition to address at TKA. The challenges are to be able to detect it at surgery and take appropriate measures in terms of resection and releases to correct it satisfactorily. Computer assisted TKA helps to achieve excellent deformity correction, limb alignment, gap balancing and function in patients with recurvatum deformity by accurately quantifying and helping to modify the amount of bone cuts and titrate soft tissue release

To describe a simple effective technique of opening wedge tibial osteotomy for the treatment of recurvatum (hyperextension) instability of the knee. Recurvatum instability of the knee occurs in patients with pathological hyperextension. There are three patterns of recurvatum instability:-. Acquired bony deformity of the proximal tibia (growth plate arrest or fracture malunion). Pathological laxity of the posterior capsule of the knee. This may occur without damage to the cruciate ligaments. A combination of bony and soft tissue pathology. All three patterns are best treated by an opening wedge tibial osteotomy at the level of the tibial tubercle. A simple surgical technique is described that does not require detachment of the tibial tubercle. The necessary degree of correction is easily assessed clinically during surgery. The technique has been used with success in 8 patients. The Puddu tooth plate provides ideal fixation. Iliac crest cortico-cancellous wedge bone grafts have been used in all cases

Congenital or acquired recurvatum genu might be caused by bone and/or soft tissue disorders. In bone recurvation, tibial deformity is more common; femoral deformity has clinical and X-ray features that are less important and often unidentified. We found this type of deformity in only four of 40 cases of bone recurvation. Bone recurvation can follow a tibial or femoral fracture as well as injury with no X-ray signs. Some months later an anterior epiphysiolisis might be recognised on X-ray. This fact allows a retrospective diagnosis of fifth type Salter-Harris epiphysiolisis. Clinically a harmonious recurvatum genu would be recognised, which is difficult to distinguish from a capsulo-ligamentous disorder. According to a subjective profile, it is featured with no objective laxity. On X-rays there are no peculiarities in the anterior view, but on the lateral view femoral condylar flattening with anterior rotation, in particular in the lateral one, can be observed. It might be useful to compare the X-ray findings to define a geometrical point termed the femoral diaphysealintercondylar angle. This has been already described and is measured between two lines, one which represents the axes of the femoral shaft, the other one the Blumensaat line; in a normal knee this angle measures 33° (±3). In knees with femoral recurvation this is higher: in our four patients the range of the angle was 45°–58°. Procurving femoral osteotomy is the gold standard; in fact femoral closed wedge osteotomy allows a complete correction. Surgeons must avoid an overcorrection with subsequent femoral trochlear rotation and at the same time a tibial osteotomy must be avoided, which would lead to a double articular deformity, wherever it would fit with a capsulo-ligamentous recurvation

Recurvatum genu can develop as a results of both chronic diseases “maladie des enfants alités” (Lefort), though rarely, and after trauma, which occurs more often. Surgical treatment might consist either in a de-epiphysiodesis according to Langenskield, when a bone bridge is present, or by Ilizarov technique, which allows a correction of segmentary shortening. This kind of trauma often occurs after bone growth has ceased and this is why in our study we performed osteotomies. Femoral osteotomies are all closed wedge procedures with medial access and 90° angle blade-plate fixation. This allows early mobilisation and avoids overcorrection. Without performing this kind of procedure posteriorisation of the trochlea might occur and, consequently, over time, patellofemoral arthritis could develop. For the tibia we applied an anterior open wedge osteotomy with ATT avulsion, according to Lecuire, with which secondary low patella can be avoided. As fixation we first used screws, actually a plate to correct the co-existing valgus. The good results of this kind of surgery justify autologus bone graft. We have not employed the the procedure described by Bowen

Introduction. Genu recurvatum is a deformity rarely seen in patients receiving total knee arthroplasty. This deformity is defined as hyperextension of the knee greater than 5°. The incidence of recurvatum has been cited in the literature as less than 1%. Purpose. The purpose of this study was to report data on 1510 consecutive total knee replacements (TKR) with navigation to demonstrate that the incidence of genu recurvatum is higher than what is cited in the literature. Methods. This is a retrospective review that was approved by our health science institutional review board. We reviewed resting, intra-operative alignment of 206 navigated total knee arthroplasty cases with recurvatum. This is data from 4 surgeons who are lower extremity joint replacement physicians. The range of motion (ROM) is measured and recorded by the attending physician during routine physical examination of the lower extremity. Demographic data was used to describe the patient group. The data will include pre-operative, intra-operative and post-operative ROM. The intra-operative data will be captured by the navigation system, this sytem is accurate to 1° and 1mm. The post-operative ROM will be obtained from an office visit. We are interested in the post-operative ROM to demonstrate correction of the recurvatum. Results. One thousand five hundred and ten primary TKR were reviewed for this study. Two hundred and six patients (13.6%) had genu recurvatum as measured by the navigation computer. The range of recurvatum was 0.5–30°; mean 5 degrees (STD 4.3°). Sixty six patients had >5 degrees of recurvatum (4.4%). Only 2 patients had recurvatum recorded on their pre-operative office visit. These 2 patients did not have extreme recurvatum, 3° and a few degrees on walking respectively. No patient had recurvatum at the 4 year visit (visit range 3 months – to 4 years). The primary diagnosis for the group was osteoarthritis, 92 %. All cases of recurvatum were treated with under resection of the femur and correction of the coronal plane. All cases were corrected intraoperatively. Conclusion. Etiology of recurvatum can be due to bony insufficiency at the anterior tibia, insufficiency at both femoral condyles or laxity of the posterior capsule and ligaments. During surgery this can be addressed by under resection of the femur and undersizing the femoral component to increase the flex space, or soft tissue tightening can be implemented. Our surgical technique aimed to balance hyperextension with reduction of the distal femoral cut. Coronal balance is also important in the management of hyperextension. Current total knee designs lack the extension cam effect and make sagital balancing critical. Recurvatum is difficult to correct after total knee arthroplasty and this issue is important to address at the time of primary surgery. The use of a navigation system helped us appreciate a deformity that is not easily detected during routine examination. This study found that genu recurvatum in patients receiving TKR is significantly higher than what is reported in the literature. This finding has important implications for the management of a small percentage but nonetheless significant number of patients. This deformity is not appreciated in the clinical setting during routine examination

There is a difference between “functional instability” of a total knee arthroplasty (TKA) and a case of “TKA instability”. For example a TKA with a peri-prosthetic fracture is unstable, but would not be considered a “case of instability”. The concept of “stability” for a TKA means that the reconstructed joint can maintain its structure and permit normal motion and activities under physiologic loads. The relationship between stability and alignment is that stability maintains alignment. Instability means that there are numerous alignments and almost always the worst one for the loading condition. In the native knee, “instability” is synonymous with ligament injury. If this were true in TKA, then it would be reasonable to treat every “unstable TKA” with a constrained implant. But that is NOT the case. If the key to successful revision of a problem TKA is understanding (and correcting) the specific cause of the problem, then deep understanding of why the TKA is unstable is essential. A case of true “instability” then, is the loss of structural integrity under load as the result of problems with soft tissue stabilizing structures and/or the size or position of components. It is rare that ligament injury alone is the sole cause of instability (valgus instability invariably involves valgus alignment; varus instability usually means some varus alignment and compromised lateral soft tissues). There will be forces (structures) that create instability and forces (structures) that stabilise. There are three categories of instability: Varus-valgus or coronal: Assuming that the skeleton, implant and fixation are intact. These are usually cases that involve ligament compromise, but the usual cause is CORONAL ALIGNMENT, and this must be corrected. The ligament problem is best solved with mechanical constraint. Gait disturbances that increase the functional alignment problems (hip abductor lurch causing a valgus moment at the knee, scoliosis) may require attention of additional compensation with re-alignment. Plane of motion: Both fixed flexion contractures and recurvatum may result in buckling. The first by exhaustion of the quadriceps (consider doing quadriceps “lunges” with every step) and the second because recurvatum is usually a compensation for extensor insufficiency. The prototype for understanding recurvatum has always been polio. This is perhaps one of the most difficult types of instability to treat. The glib answer has been a hinged prosthesis with an extensor stop but there are profound mechanical reasons why this is flawed thinking. The patient with recurvatum instability due to neurologic compromise of the extensor should be offered an arthrodesis, which they will likely decline. The simpler problem of recurvatum secondary to a patellectomy will benefit from an allograft reconstruction of the patella using a modified technique. A common occurrence is obesity with patellofemoral pain, that the patient has managed with a “patellar avoidance” or “hyperextension gait”. Plane of motion instability is a problem of the EXTENSOR MECHANISM DEFICIENCY. Flexion instability. This results from a flexion gap that is larger than the extension gap, where a polyethylene insert has been selected that permits full extension but leaves the flexion gap unstable. These patients achieve remarkable flexion easily and early, but have difficulties with pain and instability on stairs, with recurrent (non-bloody) effusions and peri-articular tenderness. Revision surgery is necessary. Flexion instability may also occur with posterior stabilised prostheses. So-called “mid-flexion” instability is a contentious concept, poorly understood and as yet, not a reported cause for revision surgery distinct from “FLEXION INSTABILITY”. Flexion instability is a problem of GAP BALANCE

Introduction. Genu recurvatum deformities are unusual before total knee arthroplasty (TKA), occurring in less than 1% of patients. The purpose of this study is to evaluate the clinical and radiographic results of primary TKA in patients that had recurvatum deformities before surgery. Patients and Methods. The inclusion criteria was to have recurvatum deformity over 10 degrees on lateral standing X-ray view. We retrospectively reviewed 22 knees with pre-operative recurvatum deformities, and the incident was 1.0% of all TKAs at our hospital. The etiology of the arthritis was osteoarthritis in 21 knees, of which 3 knees were neuropathic disease, and rheumatoid arthritis in 1 knee. There were 6 men and 16 women, and the average age was 73.3 years (range, 53 to 83 years) at the time of operation. The average follow-up period was 15 months (range, 3 to 81 months). We performed to use medial parapatellar approach and bone cutting was done by measured resection technique. The surgical knacks were resection of less distal femur and proximal tibia bone to make extension gap tightly, additionally decrease the tibial posterior slope. Posterior-stabilizer (PS) implants (NexGen LPS: Zimmer, Bisurface KU4+: JMM) were used in 20 knees and constrained implants (NexGen RH knee: Zimmer, Endo-Model Hinge Knee: Link) were in 2 knees with neuropathic joints. Results. The averaged Knee Society Knee and Function score improved from 33.1 points to 94.1 points, and 28.0 points to 60.5 points at the time of the last follow-up. The femorotibial angle changed from averaged 183.4 degrees (range, 162 to 195 degrees) preoperatively to averaged 173.3 degrees (range, 170 to 177 degrees). Preoperative hyperextension was averaged 18.2 degrees (range, 10 to 40 degrees). Intraoperatively, the hyperextension deformity was corrected in all cases. The tibial posterior slope was averaged 1.7 degrees (range, −2.7 to 6 degrees). The final hyperextension improved averaged 6.9 degrees (range, −1.7 to 26.6 degrees), all but one knee were corrected. One case treated with a standard PS type, who was associated with neuropathic disease, had a recurrence of recurvatum deformity and required revision surgery. Discussion. Recurvatum may be associated with a severe osseous deformity, capsular or ligamentous laxity, and neuromuscular disease. Surgical solutions may be to use a standard PS prosthesis with a slight underresection of the bone edge, and decrease tibial posterior slope. An alternative solution is to use a rotating-hinge prosthesis with less than antigravity quadriceps strength for neuromuscular disease

Introduction. The assessment of leg length is essential for planning the correction of deformities and for the compensation of length discrepancy, especially after hip or knee arthroplasty. CT scan measures the “anatomical” lengths but does not evaluate the “functional” length experienced by the patients in standing position. Functional length integrates frontal orientation, flexion or hyperextension. EOS system provides simultaneously AP and lateral measures in standing position and thus provides anatomical and functional evaluations of the lower limb lengths. The objective of this study was to measure 2D and 3D anatomical and functional lengths, to verify whether these measures are different and to evaluate the parameters significantly influencing these potential differences. Material and Methods. 70 patients without previous surgery of the lower limbs (140 lower extremities) were evaluated on EOS images obtained in bipodal standing position according to a previously described protocol. We used the following definitions:. anatomical femoral length between the center of the femoral head (A) and center of the trochlea (B). anatomical tibial length between the center tibial spine (intercondylar eminence) (C) and the center of the ankle joint (D). functional length is AD. global anatomical length is AB + CD. Other parameters measured are HKA, HKS, femoral and tibial mechanical angles (FMA, TMA), angles of flexion or hyperextension of the knee, femoral and tibial torsion, femoro-tibial torsion in the knee, and cumulative torsional index (CTI). All 2D et3D measures were evaluated and compared for their repeatability. Results. Regarding repeatability, an ICC> 0.95 was found for all measurements except for the tibial mechanical angle (0.91 for 2D, 3D 0.92 for 3D). We observed 54/140 lower limbs with Flessum/Recurvatum angles (FRA) >10°. 2D results (mean, SD) were. 41,8mm(2,9) for femoral anatomical length. 36,1mm(2,8) for tibial anatomical length. 78,0mm(5,4) for global anatomical length. 78,5 mm(5,5) for functional length. 7,4°(12,0) for Flessum/Recurvatum angle. −1,5°(6,4) for HKA. 4,9°(2,0) for HKS. 92,1°(3,4) for FMA. 87,1°(3,4) for TMA. 3D results (mean, SD) were. 42,4mm (2,8) for femoral anatomical length. 36,6mm (2,8) for tibial anatomical length. 79,0mm (5,4) for global anatomical length. 78,9mm (5,5) for functional length. 7,2°(12,0) for Flessum/Recurvatum angle. −1,0°(5,9) for HKA. 4,9°(1,5) for HKS. 92,7°(2,7) for FMA. 87,9°(3,9) for TMA. The 2D/3D measurements of functional lengths were statistically significant (p <0.0001. Student's test). For anatomical lengths. 2D/3D measurements were also statistically significant (p <0.0001. Student's test for femoral tibial and global anatomical lengths). Some parameters significantly influenced 2D/3D differences:. for the global anatomical length: FRA P<0,0001, TMA P=0,0173, HKA P=0,0259 and femoro-tibial torsion P=0,0026. for the functional length FRA P=0,0065. Discussion and conclusion. EOS imaging allows to accurately assess the anatomical and functional length experienced by the patient. These new data open new perspectives for planning length or axis corrections and for an optimized evaluation in some medico legal issues after joint replacement or posttraumatic sequelae. This study points out the importance of 3D measurements in outliers cases (varus or valgus cases, flessum or recurvatum of the knee)

Performing a total knee arthroplasty in a patient with a flexion contracture or recurvatum deformity requires from the surgeon an adequate knowledge of the principles of flexion – extension space balancing. In the standard TKA procedure, adequate balancing between the flexion and extension space is usually easily achieved, leading to an equal and symmetrical space both in flexion and extension, which results in a stable knee and maximal range of motion after implantation of the prosthetic components. The situation is different in the knee with a flexion contracture or recurvatum, where the extension space is relatively smaller (flexion contracture) or greater (recurvatum) than the flexion space. In both of these situations, the flexion and extension space should be balanced by the surgeon in order to avoid an important deficit in range of motion or an instability problem. Several surgical techniques are available for this. In the knee with a flexion contracture, the extension space is relatively too small. Adequate removal of posterior osteophytes will increase the extension space, and this should be the first step in the flexion – extension space procedure (1). Next, the collateral structures should be balanced, with release of the tight structures that are effective in extension only (2). These are predominantly the iliotibial band in the valgus knee, and the posterior oblique ligament in the varus knee. If these 2 steps are not sufficient, proximalisation of the femoral component by 2 to 3mm may be required (step 3), or a formal release of the posterior capsule from the posterior femoral condyles (4). When an anterior reference system is used, the surgeon can also decide to use a slightly larger femoral component with a slightly increased tibial resection to equalise the gaps (5). In the knee with a recurvatum deformity, the extension space is relatively too large. In this situation, distalisation of the femoral component by removing 2 mm less distal femoral bone, will decrease only the extension space without altering the flexion space (1). In case of anterior referencing, the use of a slightly undersized femoral component will further equalise the gaps (2). Just using a thicker tibial insert to fill up the extension space, while increasing the flexion space by resecting the PCL or increasing the tibial slope, may be another option in the modest recurvatum knee (3)

Introduction. To report our early experience and suitability over unicortical fixation system to reduce and hold the bone fragments in position during a CHAOS procedure of the femur or tibia during lower limb reconstruction surgery. Materials and Methods. We report a case series of the first consecutive 10 patients (11 bones) for which this CHAOS technique was used between May 2017 and October 2019 by the same surgeon. The novel aspect of the procedure was the use of a unicortical device, Galaxy UNYCO (Orthofix, Verona, Italy), which eliminate the need for any change of fixation during the procedure. It also means the intramedullary canal was left free for the intramedullary nailing. Results. We treated 4 femurs and 7 tibias with this technique without any loss or failure of the construct. We treated uniplanar and multiplanar deformities with the angulations between 8 degrees of valgus to 15 degrees of varus and from 0 to 8 mm translation in the AP view, from 20 degrees procurvatum to 15 degrees recurvatum and 0 to 2 mm translation on the lateral view and from 20 degrees internal rotation to 5 degrees external rotation and 0 to 10 mm translation on axial view. Conclusions. The construct was able to deal with the total tension in the system both in the correction phase and the additional stress applied during insertion of a nail such as reaming and impacting the nail to the canal. The potential advantage also included the possibility of intramedullary nailing without interference with the external fixation device

Total knee arthroplasty is well documented to be a very successful operation, proper alignment and soft tissue balancing is important. Computer navigation for TKA has been available for more than 10 years. This paper reviews our outcomes and the lessons learned from CAS. October 1, 2001 we preformed the first clinical case of a navigated TKA in North America. We tracked our early results at with 1 year of follow up of 150 navigated knee cases and compared there data to 50 non- navigated knees. Long standing lower extremity x-rays were measured to determine mechanical alignment. In 2011 we reviewed all cases to date to determine if there were pin site problems. In 2012 we looked at are recurvatum data. Oct 2011 was our 10. th. year using the computer navigation system for TKA. We reviewed what we have learned and assess our outcome data on patients who were at least 9.5 years post surgery. All patients received long standing lower extremity x-rays pre-operatively and at 10 year follow up. Any problems or revisions were noted. Our early results will be compared to our 10 year results. Our 1 year results showed no difference in clinical outcome or range of motion compared to the non-navigated group. The navigated knee group had better alignment; 52% were in neutral alignment, vs. 23% in the non-navigated group. Overall the navigated group, 80% of all alignment was within 1.5 degrees of neutral while the non-navigated groups 80 % of cases were between 5° valgus and 4° varus. Our data for 10 year follow up (range 9.5–10.5 years) is the similar to our early results. We have seen 42 patients, 44 knees. The alignment from long standing lower extremity x-rays, 53% were neutral or +/− 1°. Twenty eight knees of 43 were +/− 3°. There were 3 revisions in this small group. One was revised for a loose tibial base plate with osteolysis on the tibia and femur. The revision was 10 years after the index surgery. There were 2 other revisions, both for infection, were treated with a poly exchange and wash out. To date we have done 2030 navigated knee cases and our data shows that 13.9% demonstrate genu recurvatum. The range was 0.5° to 30°, 104 patients, 5.1% had more than 5° recurvatum. In the literature recurvatum rates are reported at about 1%. After reviewing all case to date in we did not observe any pin site problems. CAS is still the main objective measure we have in the operating room to date. The advantages of CAS are it provides real time assessment of the true varus/valgus deformity, initial extension and medial/lateral soft tissue imbalance and anticipates final trial reduction. We are performing less soft tissue releases most likely because our tibia and femoral cuts are more precise. Our 10 year follow up data while encouraging requires more investigation

Objective: To study deformities in tibial fractures that are treated orthopedically. Material and Methods: A prospective study of 42 tibial fractures treated orthopedically (1996–2003), Average age was 8.9 years, Nineteen (45.2%) were male and 23 (54.3%) were female. Average follow-up was 59.6 months. Nineteen of the fractures (45.2%) were medial third and 23 (54.8%) were distal. The fracture line was spiral in 26 cases (61.9%), oblique in 10 cases (23.8%) and transverse in 6 (4.8%). In 18 cases (42.9%), there was a facture of the fibula and in 24 cases there was not (57.1%). Exclusion criteria: previous fractures, angular deformities less than 5 and surgical treatment. At one year post-concolidation, antero-posterior and lateral X-rays were taken and if the angular deformity was greater than 5 a tibial CT was done to measure axial rotation. Descriptive statistical and non-parametrical studies was done with signification p < 0.05. Results: Varus deformity was 5.8, valgus 6, recurvatum 6.5 and antecurvatum 4, In 23 cases (54.8%), an association varus and recurvatum was found, in 9 cases (21.4%) valgus- recurvatum were associated, and in five cases each there was varus- and valgus- antecurvatum associations (11.9%). Healthy tibia had an external rotation of 38.2, while the rotation of fractured tibia was virtually the same at 38.5. In fractures of the medial third, external rotation decreased 8.3(55.6% cases). When the fibula was intact, external rotation was 6.4(40%) and decreased 8.7 (17.5%). When was fractured, decreased 6.5(30% cases). Localization and fracture line had no impact on results. external tibial rotation was greater for intact fibula than for fractured ones (p= 0.03). Conclusions: 1) The majority of tibias treated orthopedically consolidated in varus or valgus-antecurvatum, 2) When there was a lesion of the fibula, the consolidation of the external rotation of the tibia increased, when there was no lesion to the fibula, it decreased

Background. A grossly deformed knee is believed to be an indication for PS -TKA. However, the role CR-TKA in such knees is unclear in the literature. Considering the obvious advantages of CR, we analysed the mid term follow up of CR knees in gross deformities. Materials and Methods. 1590 patients (1740 knees) underwent TKA between January 2011 to December 2012, out of which 570 knees had gross deformity (varus > 15°, FFD > 10°, valgus > 10°, recurvatum > 10). CR-TKA was performed for 540 knees and were included in our study. Subvastus approach was used for all knees. Average age being 68 years, mean BMI being 32 and average weight 70 kgs. Intraoperatively, POLO test was used to ensure PCL stability, further confirmed by direct palpation. Femoral roll-back was found adequate. Results. 95% of grossly deformed knees underwent CR-TKA. Mean pre-operative knee score was 45 which improved to 94 at mid-term follow-up at 18 to 36 months. There were no incidence of component loosening or instability. Three knees needed secondary resurfacing of patella. One knee got infected for which components were explanted and joint debrided thoroughly. Lateral radiographs showed consistent roll-back in all except for 3 knees which had femoral roll-forward. Discussion. PS-TKA have shown to yeild good results in gross deformities, however the role of CR had been unclear. Contrary to popular belief, in our opinion, greater the deformity, greater is the need to retain the PCL. Balancing the flexion extention space is easier and involves lesser resection of distal femur. Hence, its bone preserving. For valgus knees, PCL acts a medial stabilizer. In recurvatum deformity, the posterior capsule being stretched out, retaining PCL has prime importance. Our retrospective mid term follow up have shown good results. However, long term analysis is necessary to highlight the survivorship. Conclusion. CR-TKA must be considered for knees with gross deformity for its aforementioned advantages

Purpose: Retrograde nailing is emerging among methods proposed or stabilisation of femoral fractures above total knee arthroplasties (TKA). Material and methods. Between June 1994 and may 2000, 12 fractures above TKA were treated by retrograde nailing. These fractures occurred 43 months (4–51) after implantation of the TKA in three men and women aged 74 years (43–88). The fracture was situated just above the prosthetic trochlea in ten, and distant from the implant in two. The posterior cruciate ligament was preserved in six TKA and six were posterior stabilised prostheses. Indications for arthroplasty were degenerative joint disease in nine and rheumatoid polyarthritis in three. Four patients had proximal implants (one fixation and three prostheses). A percutaneous approach was used except for three cases in order protect the tibial component. Closed reduction was achieved, but required an open reduction for completion in two cases. the nail was advanced just to the trochlea in patients with a preserved posterior cruciate ligament and beyond the posterior stabilisation cage for the posterior stabilised implants. The knee was mobilised immediately after surgery and total weight-bearing was encouraged four to six weeks later. Results: There was one error in the proximal aiming, one metastatic infection from a leg ulcer at three months and one tibial loosening in a polyarthritic woman 66 months after arthroplasty, i.e. 51 months after the fracture. Bone healing was achieved at two to four months. Frontal deviation was less than 5°. Recurvatum was less than 5° in eight cases, between 5° and 10° in two cases and between 10° and 20° in two others. At mean follow-up of 23 months (3–60), maximal moss of mobility was 10°. There was not worsening of pain. Discussion: Retrograde nailing leads to bone healing with satisfactory frontal alignment and minimal loss of mobility. The approach uses the initial incision, facilitating complementary procedures or revision if needed. The main problem is controlling recurvatum, even though at the follow-up reported there was no clinical impact or loosening. The limitations of this method are well defined: free medullary canal, sufficient knee flexion, compatible femoral component. The tibial obstacle in posterior stabilised implants is less well known; It should be protected during the nailing if it is high. The polyethylene insert may have to be removed temporarily in certain cases. Conclusion: The two principal problems with retrograde nailing are recognising implants compatible with this technique and controlling recurvatum. Results are acceptable with a minimally invasive technique

The advent of Elastic Stable Intramedullary Nailing has revolutionised the conservative treatment of long human bone fractures in children (Metaizeau, 1988; Metaizeau et al., 2004). Unfortunately, failures still occur due to excessive bending and fatigue (Linhart et al., 1999; Lascombes et al., 2006), bone refracture or nail failure (Bråten et al., 1993; Weinberg et al., 2003). Ideally, during surgery, nail insertion into the diaphyseal medullary canal should not interrupt or injure cartilage growth; nails should provide an improved rigidity and fracture stabilisation. This study aims at comparing deflections and stiffnesses of nail-bone assemblies: standard cylindrically-shaped nails (MI) vs. new cylindrical nails (MII) with a flattened face across the entire length allowing more inertia and a curved tip allowing better penetration into the cancellous bone of the metaphysis (Figure 1). MII exhibits a section with two parameters: a diameter C providing nail stiffness and a height C' providing practical dimension when both nails are crossed at the isthmus of the diaphysis: C/C' is set to 1.25 for all MII nails. A CT scan of a patient aged 22 years was used to segment a 3D model of a 471mm-long right femur model. The medullary canal diameters at the isthmus are 10.8mm and 11.4mm in the ML and AP direction, respectively. Titanium-made CAD models of MI (Ø=4mm) and MII (flat face: Ø=5mm) were pre-curved to maintain their flat face and carefully placed and positioned according to surgeon's instructions. Both nails were inserted via lateral holes in the distal femur with their extremities either bumping against the cortex or lying in the trabecular bone. Transverse and comminuted fractures were simulated (Figure 1). For each assembly, a Finite Element (FE) tetrahedral mesh was generated (∼100181 nodes and 424398 elements). Grey-scale levels were used to assign heterogeneous material properties to the bone (E=6850 ρ. 1.49. (Morgan et al., 2003)). Two modes of loading were considered: 4-point bending (varus and recurvatum: F. max. =6000N) and internal torsion (M. max. =70kNmm). This led to the simulation of 15 FE models, including a reference intact femur. Results show that in valgus, for the transverse (comminuted) fracture, the mean displacement of the assembly decreased by around 50%: from 15.24mm (27.49mm) to 8.15mm (13.85mm) for MI and MII, respectively, compared to 3.59mm for the intact bone. The assembly stiffness increased by 87% and 99% for transverse and comminuted fracture, respectively (Table 1). Similar trends were found in recurvatum with higher increases in assembly stiffness of 170% and 143% for transverse and comminuted fracture, respectively (Table 1). In torsion, for the transverse (comminuted) fracture, the measured angle of rotation decreased from: 0.43rad (0.66rad) to 0.22rad (0.43rad) for MI and MII, respectively, compared to 0.09rad for the intact bone. This corresponded to an increase of 95% and 55% in assembly stiffness for transverse and comminuted fracture, respectively. In conclusion, using the 5mm-diameter new nails (MII) for the same intramedullar space, during either bending or torsion, assemblies were always stiffer than when using standard cylindrical nails

Instability currently represents one of the main causes of residual pain and symptoms following TKA and thus is a major cause of revision total knee replacement, second only to component loosening in some series. Instability related to ligamentous laxity can be categorised by the pattern of relative laxity of the soft tissue structures and this in turn helps in determination of the bony alignment issue, component sizing or positioning problem or ligamentous abnormality that may be contributory and require correction. Instability patterns associated with TKA can be symmetrical and global type instability where there is laxity in all planes, and can also more commonly be asymmetrical or isolated laxity problems where there is good stability in some planes or positions of the knee but excessive laxity in at least one direction. Isolated laxity problems can be subcategorised into one of 3 patterns: Extension instability, Flexion instability, and Recurvatum. Global laxity can occur due to inadequate tibial component thickness, or globally incompetent soft tissues, and can present initially after TKA or alternatively can present late from slow stretch of soft tissues over time as can be seen with some pathologic states. Asymmetrical or Isolated laxity occurs in the sagittal plane when medial vs. lateral “gaps” are unequal and may be due to contracture of tight structures either medially or laterally or can be due to insufficiency or injury of the ligamentous structures on one side vs. the normal structures on other side. Occasionally there is a combination of both contracture on one side and attenuation/stretch on the other side as seen in some patients with severe long standing genu varum or genu valgum. Asymmetrical laxity in the frontal plane generally results in unequal extension vs. flexion “gaps”. This can cause either anteroposterior laxity in flexion but full extension with good stability or alternatively, there may be AP stability in flexion but a lack of full extension in the presence of the exact same pattern of imbalance when a “too thick” polyethylene insert is used to correct what would otherwise be flexion instability. In both cases, the extension gap is tighter than the flexion gap. Isolated recurvatum occurs when the posterior capsular structures are relatively lax or deficient so that a knee that is otherwise stable in the medial-lateral plane in extension, and is stable in the AP plane when in flexion, hyperextends in the fully extended position. In any TKA procedure (but especially revision for instability) it is critical to understand the effect of selected bone resection (or build ups) on soft tissue balancing in order to avoid or treat ligamentous laxity: distal femur – effects extension gap only; posterior femur – effects flexion gap only; proximal tibia – both flexion and extension spaces. During revision for instability, careful evaluation of the cause of the laxity and failure is critically important, especially if there is associated axial deformity or malalignment which generally must be corrected for any reconstruction or revision components to work. Most knees revised for instability issues will require a posterior stabilised or constrained condylar design. Constrained condylar implants are used to compensate for residual medial-lateral imbalance still present after standard soft tissue releases medially (subperiosteal tibia) or laterally (vis selective pie-crust method). However, if the patient displays residual major medial-lateral or global instability that cannot be corrected, or when there is an excessive flexion gap that cannot be stabilised with maximal allowable component sizing, a rotating hinge constrained total knee replacement design may be required. Recent data has shown that rotating hinges can work reliably in restoring stability to the knee in such cases with satisfactory durability and clinical results over time

An important goal of total knee replacement is deformity correction. Arthritic narrowing can be accompanied by a fixed shortening of the collateral ligament on the same side of the narrowing. There can also be ligamentous laxity that develops in the opposite compartment. Flexion contracture can develop with tightening of the posterior capsule. Successful total knee replacement requires proper bone resection along with gap balancing and balanced collateral ligament tensioning. Beware of correctable deformities, as the collateral ligament may have kept its resting length and therefore the knee becomes stable after the bone resections are made and the spacer block is inserted to test the stability of the knee in flexion and extension. In the varus knee, the MCL may be contracted. A medial release of the superficial medial collateral ligament may be necessary. This can be done by stripping the periosteal insertion of the MCL. A stretch may be accomplished by placing a laminar spreader in the narrow medial joint space and opening the space until the MCL stretches from its insertion. This maneuver will require a further increase in polyethylene thickness height of 2 – 4mm. Krackow has also on occasion done a surgical imbrication of the LCL, if it appears attenuated on the lateral side of a severe varus deformity. For valgus deformities, the LCL, arcuate ligament and popliteus and ITB can be contracted. At this time, most authors recommend preservation of the popliteus tendon as it affects primarily the flexion gap. In extension there has been consensus that the surgeon should release what is tight. This may include the ITB release in a pie-crust fashion, or off the Gerdy's tubercle and then a selective release of the arcuate ligament complex. Krackow has also utilised tightening imbrication of the MCL if it is severely attenuated and lax. This has been used infrequently, however. To avoid overlengthening of the knee by referencing balance off of the lengthened, attenuated MCL in cases of severe valgus deformity, less release is performed and a CCK implant may be used. For severe flexion contractures, the posterior osteophytes should be first aggressively removed. The posterior joint capsule can be stripped off the distal femur and sometimes the gastrocnemius muscle insertions can be dissected free. After these maneuvers, proximal raising of the joint line by resection of the distal femur can be utilised. In ankylosis with severe flexion contracture, constrained implants will be needed if the proximal resection extends above the insertion of the collateral ligaments. Recurvatum is a rarely seen deformity that is usually associated with an extraordinarily weak or paretic quadriceps. The joint capsule has become stretched over time. Careful balancing of the knee is necessary. But, if the recurvatum still persists, distally augmenting the femur is an option. And no releases are required

In this retrospective radiographic review, we compared the adequacy of reduction of 18 femoral fractures treated by retrograde and 35 fractures treated by pro-grade nailing. The groups were similar with regard to age, gender and side of the fracture. In the prograde group, there were eight fractures of type A5, 25 of type A3 and two of type C2. In the retrograde group there were two type-A2 fractures, 14 type-A3 and two type-C2. On the Winquist classification there were eight group-0, two group-1, two group-3 and 23 group-4 fractures in the prograde group, and two group-0, one group-3 and 15 group-4 fractures in the retrograde group. We measured the lateral femoral angle (LFA) from the anatomical axis to assess alignment postoperatively. We considered an LFA value of 83( normal and LFA values between 78( and 88( acceptable. The LFA was greater than 88( in 3% of the prograde group and in 6% of the retrograde group. In the prograde and retrograde groups, 86% and 83% of the nails respectively were in the acceptable range. In both groups, the LFA was less than 78( in 11%. There was shift of more than 1 cm in 17% of the prograde and in 44% of the retrograde groups. Recurvatum of more than 5( was seen in 31%( of prograde and 22% of retrograde nailings. In the retrograde group, 67% of nails were distal to the femoral notch on the lateral radiograph and were deemed to be proud. We concluded that prograde and retrograde nailing of distal third femur fractures gave comparable results in terms of alignment, but that recurvatum could be problematic with prograde nailing and that shift and proud nails were a concern with retrograde nailing. The clinical significance of these results has still to be determined

Our research group has recent clinical experience with our novel computer-assisted method of bone deformity correction using the Taylor spatial frame (Smith & Nephew, Memphis, TN). Practitioners of the Taylor spatial frame admit that there is a steep learning curve in using the frame. This is in large part due to the difficulty in accurately measuring 13 frame parameters and mounting the frame to the patient without inducing residual rotational and translational errors. Our technique aims to reduce complications due to these factors by preoperatively planning the desired correction and calculating the correction based on the actual three-dimensional location of the frame with respect to the anatomy, rather than from traditional radiographs. The surgeon has greater flexibility in choosing the position of the rings since this technique does not depend on placing the rings in a particular configuration. Four clinical procedures have been performed at Kingston General Hospital (Kingston, ON, Canada) to date. The first patient presented with a proximal tibial growth-plate arrest that was secondary to a fracture. The result was a recurvatum deformity secondary to an eccentric growth arrest anteriorly. This deformity caused a stretch of the posterior capsule and posterior cruciate ligament that produced an unstable knee. The achieved correction, measured radiographically, was from an initial; − 14 degrees to a final +7 degrees of posterior slope. The second patient presented with a proximal tibial soft tissue imbalance that was thought would eventually lead to a recurvatum deformity. An increase in the posterior slope of the tibia was induced to compensate for the soft tissue deformity. The radiographic correction was an increase in posterior slope from +7 degrees to +14 degrees and from 5 degrees varus to 8 degrees varus. The third patient patient presented with a partially-healed malunited tibial fracture with 14 degrees of proximal tibial varus and 16 degrees of posterior slope. In spite of an uncomplicated frame application, the patient was not compliant with post-operative care and the frame was removed before correction could be achieved. The fourth patient underwent a limb lengthening. At the time of writing, the adjustment schedule had not been completed. Our computer-assisted procedure appears to be an effective method of improving Taylor spatial frame use. The senior surgeon (DPB) noted that the procedure is easy to perform, he no longer needs to measure the 13 frame parameters, and he can plan the correction in three dimensions. We also have the ability to modify the pace of the correction schedule to accommodate the rate of bone growth for each individual patient. Drawbacks of the technique include the requirements for a preoperative CT scan and a segmentation of the scan to produce the three-dimensional computer models

There are many challenges facing the revision knee surgeon. Bony defects, ligamentous imbalance, and difficult gap balancing scenarios are common and require practical management strategies. Typically, an implant with the least amount of constraint necessary to provide a well-aligned, well-balanced arc of motion is preferred. Constraint in implants increases the stresses on both the bearing surfaces and the bony interfaces and may result in earlier mechanical failure of the implant. Despite this fact, there are situations where one cannot rely on a simple larger polyethylene post (such as found in CCK type devices) to balance gaps. The author prefers to choose hinge-type devices in situations that demonstrate massive gap imbalance (typically huge flexion gaps), situations with deficient extensor mechanisms that can result in recurvatum stresses, or in situations of global ligamentous instability. Techniques of supporting the bony interfaces with stems and sleeves may improve the longevity of these constructs. Complications are common, including extensor mechanism problems. Multiple studies have demonstrated reasonable results of hinged implants for these challenging revision scenarios, and the hinge should remain in the armamentarium of the revision surgeon