Introduction. Total ankle replacement (TAR) is surgically complex; malalignment can arise due to surgical technique or failure to correct natural varus/valgus malalignment. Across joint replacement, malalignment has been associated with pain, component edge loading, increased wear and higher failure rates. Good component alignment is considered instrumental for long term TAR success. The conforming surface geometry of mobile bearing TARs leaves no freedom for coronal plane malalignment. The aim of this study was to investigate the biomechanical effect of coronal alignment on a mobile bearing TAR. Methods. Three TARs (Zenith, Corin Group) were tested under five coronal malalignment angles from 0–10° in a single station electromechanical knee simulator applying a typical ankle gait profile. As swing phase load is critical to TAR contact mechanics but will vary depending on the joint laxity. Swing loads of 100N, 300N and 500N were investigated. A positive control test with a swing load of 1000N was also studied, and was expected to eliminate the majority of lift off effects. Under each condition, the version was allowed to move freely while tests were performed, and the version profile under each alignment angle was recorded. Each test was carried out for 600 cycles in 25% bovine serum. Under the same loading conditions, but without lubrication, a Tekscan sensor recorded data from two cycles to assess the change in contact pressure and area at the five coronal angles. Results. Across the three TARs the effect of the swing phase load varied the biomechanics with a similar pattern. The high swing load of 1000N eliminates the majority of version while with 100N swing loads the TAR abducts for the length of the swing phase only realigning when the force increases, the extent dependent on the malalignment angle. At both 300N and 500N swing loads there is an oscillation apparent which changes the contact mechanics. The Tekscan results (Figure 1b) show changes in the contact area at three points in the load cycle; swing, the lower peak and the peak load (Figure 1a). With any degree of malalignment, component lift off is highly prevalent under lower swing phase loads of 100–300N. As the swing load is increased, this effect is only noticeable at greater malalignment angles. Discussion. The observed component lift off results in edge loading and peak pressures occurring at the insert edges. When the insert is 10 degrees coronally malaligned and the insert is brought fully into contact, the peak pressure reaches 16–18MPa, a pressure similar to the yield stress of polyethylene. The high contact pressures will likely elevate the wear and may increase the potential for polyethylene failure. Conclusion. Biomechanical testing has shown the malalignment of a total ankle replacement combined with the joint tension may change the contact mechanics and potentially increase wear. For any figures or tables, please contact authors directly (see Info & Metrics tab above).

Introduction. Torsional malalignment syndrome (TMS) is a unique combination of rotational deformities in the lower limb, often leading to severe patellofemoral joint pain and disability. Surgical management of this condition usually consists of two osteotomies in each affected limb, with simultaneous correction of both femoral anteversion and external tibial torsion. However, we believe that a single supratubercular osteotomy followed by tibial derotation with the Taylor Spatial Frame (TSF) can be used to provide a significant improvement in both appearance and function. Materials and Methods. This is a retrospective case analysis in which we will be reviewing 16 osteotomies performed by one surgeon between 2006 and 2017. The study includes 11 patients with a mean age of 16.7 ± 0.8 years. Pre and post-operatively, patients were fully evaluated through history and physical examination, and CT rotational profiling. Statistical analyses were performed in order to determine whether or not any observed clinical or cosmetic improvements were statistically significant. Results. The results show significant improvements in scores reported on post-operative functional assessment, with mean Oxford Knee Score (OKS) increasing by 18.3 and mean Kujala Anterior Knee Pain Scale (AKPS) also increasing by 31.4. In addition to this, post-operative clinical assessment showed a reduced thigh-foot angle (TFA) in all cases, by a mean value of 31.9o. The angle of the transmalleolar axis (TMA) was successfully reduced in 14/16 cases, by a mean value of 8.6o. Statistical analysis showed all of these results to be statistically significant where p<0.05. Conclusions. The results show that supratubercular osteotomy, followed by gradual correction with TSF, can be used to provide a significant improvement in both appearance and function for patients suffering from TMS

Femoral shaft fractures are fairly common injuries in paediatric age group. The treatment protocols are clear in patients of age less than 4 years and greater than 6 years. The real dilemma lies in the age group of 4–6 years. The aim of this study is to find whether a conservative line should be followed, or a more aggressive surgical intervention can provide significantly better results in these injuries. This study was conducted in a tertiary care hospital in Bhubaneswar, India from January 2020 to March 2021. A total of 40 patients with femur shaft fractures were included and randomly divided in two treatment groups. Group A were treated with a TENS nail while group B were treated with skin traction followed by spica cast. They were regularly followed up with clinical and radiological examination to look out for signs of healing and any complications. TENS was removed at 4–9 months’ time in all Group A patients. Group A patients had a statistically significant less hospital stay, immobilisation period, time to full weight bearing and radiological union. Rotational malunions were significantly lower in Group A (p-value 0.0379) while there was no statistically significant difference in angular malunion in coronal and sagittal plane at final follow up. Complications unique to group A were skin necrosis and infection. We conclude that TENS is better modality for treatment of shaft of femur fractures in patients of 4–6 years age as they significantly reduce the hospital stay, immobilization period and rotational malalignment

Background. The purpose of this study was to analyze the effect of femorotibial alignment (FTA), femoral and tibial component alignment, correction of malalignment, and thickness of tibial osteotomy on implant loosening following total knee replacement. Methods. We retrospectively reviewed 107 knees in 65 patients with a minimum of six months of follow-up. The 107 knees were operated by two surgeons using BS4+ (Bisurface 4 plus) implant (Japan Medical Materials, Japan); the femoral component was cemented, and the tibial component was either cemented or not cemented by using four screws. All the replacements were performed under same operative procedure with medial para-patellar approach and measured bone technique. The knees were classified into two groups (: I and U) on the basis of postoperative radiological findings that indicate the loosening of tibial components. First, there were not any apparent loosening symptom like radio-lucent lines nor sinking; group-I (intact, n=75). Second, there were some radio-lucent lines around tibial component; subgroup-R (radio-lucent lines, n=25), or some subsidence of component over 2 mm; subgroup-S (subsidence, n=7), and the latter two subgroups were put into group-U (unstable, n=32) all together. We measured preoperative and postoperative alignment (overall FTA, correction of malalignment, and alignment of the tibial and the femoral component in the coronal plane). Furthermore, each thickness of tibial osteotomy was measured with use of preoperative and postoperative radiographs of the knee. These parameters including patient's BMI were compared between two major groups statistically to evaluate the factor influencing the stability of tibial components. Moreover, the thickness of tibial osteotomy were compared between two subgroups. Results. Radio-lucent lines were seen in any fixation (cement: 14, cementless: 11), but subsidence were found in 7 cementless screwed fixation. Average alignment of femorotibia or component were satisfactory (judged by the Knee Society Roentgenographic Evaluation), and were not different between two groups. We found that the change of FTA (I: 9.5 versus U: 12.9 degrees) and the outlier of FTA (I: 2.4 versus U: 3.1 degrees) were greater in group-U than those in group-I (p=0.002, p=0.023). In the thickness of tibial osteotomy, no significant differences were seen between two major groups, but the osteotomy were thicker in subgroup-S (12.0 mm) than in subgroup-R (9.6 mm, p = 0.03). Another parameters including BMI were not different between two groups, respectively. Conclusions. Attaining neutrality is important in stabilizing tibial component of total knee replacement. However, the larger the correction of malalignment, the more unstable the fixation of component tend to become. High-flexion femoral component designs including BS4+ require the removal of 2 to 3 mm more bone from the component-bone interface than with standard implants, generally. Nevertheless, thicker osteotomy of tibia may be a risk factor of subsidence of tibial component. We should take into account cement fixation in such cases like severe malalignment or thicker osteotomy in total knee replacement

INTRODUCTION

The increasing incidence of periprosthetic femoral fractures (PFF) after total hip arthroplasty presents growing concerns due to challenges in treatment and increased mortality. PFF are often observed when the prosthesis is implanted in varus, especially with blade-type stems. To help elucidate its impact on the PFF risk, the specific research question is: What is the effect of misalignment of a blade-type stem (resulting in down-sized prosthesis) on 1)the distribution and magnitude of cortical stresses and 2)implant-bone micromotion.

Introduction. Coronal malalignment and leg length discrepancies (LLD) are frequently associated. Temporary hemiepiphysiodesis (tHED) is commonly employed for the correction of limb malalignment in skeletally immature patients. For treatment of LLD greater than 2 cm, lengthening with intramedullary legnthening nails is a safe and reliable technique. However, the combined application of these approaches in skeletally immature patients has not yet been investigated. Materials & Methods. Retrospective radiological and clinical analysis of 25 patients (14 females, 11 males) who underwent intramedullary femoral lengthening with an antegrade PRECICE® lengthening nail as well as tHED of the distal femur and / or proximal tibia between 2014 and 2019. tHED was conducted by implantation of flexible staples (FlexTack™) either prior (n = 11), simultaneously (n = 10), or subsequently (n = 4) to femoral lengthening. The mean follow-up period was 3.7 years (±1.4). Results. The median initial LLD was 39.0 mm (35.0–45.0). 21 patients (84%) presented valgus and 4 (16%) showed varus malalignment. Leg length equalization was achieved in 13 patients at skeletal maturity (62%). The median LLD of patients with a residual LLD > 10 mm was 15.5 mm (12.8–21.8). Limb realignment was obtained in nine of seventeen skeletally mature patients (53%) in the valgus group, and in one of four patients (25%) in the varus group. Conclusions. The combination of antegrade femoral lengthening and tHED can efficiently correct LLD and coronal limb malalignment in skeletally immature patients. Nevertheless, achieving limb length equalization and realignment may render difficult in cases of severe LLD and angular deformity. Furthermore, the reported techniques ought to be thoroughly planned and executed and require regular clinical and radiological examinations until skeletal maturity to avoid - or timely detect and manage - adverse events such as overcorrection and rebound of deformity

This study aimed to examine the effect of high tibial osteotomy (HTO) on the ankle and subtalar joints via analysis of static radiographic alignment. We hypothesised that surgical alteration of the alignment of the proximal tibia would result in compensatory distal changes. 35 patients recruited as part of the wider Biomechanics and Bioengineering Centre Versus Arthritis HTO study between 2011 and 2018 had pre- and postoperative full-length weightbearing radiographs taken of their lower limbs. In addition to standard alignment measures of the limb and knee (mechanical tibiofemoral angle, Mikulicz point, medial proximal tibial angle), additional measures were taken of the ankle/subtalar joints (lateral distal tibial angle, ground-talus angle, joint line convergence angle of the ankle) as well as a novel measure of stance width. Results were compared using a paired T-test and Pearson's correlation coefficient. Following HTO, there was a significant (5.4°) change in subtalar alignment. Ground-talus angle appeared related both to the level of malalignment preoperatively and the magnitude of the alignment change caused by the HTO surgery; suggesting subtalar positioning as a key adaptive mechanism. In addition to compensatory changes within the subtalar joints, the patients on average had a 31% wider stance following HTO. These two mechanisms do not appear to be correlated but the morphology of the tibial plafond may influence which compensatory mechanisms are employed by different subgroups of HTO patients. These findings are of vital importance in clinical practice both to anticipate potential changes to the ankle and subtalar joints following HTO but it could also open up wider indications for HTO in the treatment of ankle malalignment and osteoarthritis

Introduction. Patients undergoing total knee arthroplasty (TKA) with end-stage osteoarthritis of knee have secondary foot and ankle pathology. Some compensatory changes occur at ankle and subtalar joint secondary to malalignment and deformity at the knee joint. Purpose was to evaluate the changes in hindfoot malalignment and foot deformities in patients with advanced osteoarthritis of knee requiring TKA and effect of correction of knee deformities post TKA on foot/Ankle alignment. Methods. 61 consecutive patients with Kellgren-Lawrence grade IV osteoarthritis knee undergoing TKA were enrolled in a prospective blinded study. Demographic data, deformities at knee and ankle, hindfoot malalignment and functional outcome scores such as VAS, KSS, WOMAC scores, Foot and Ankle Disability Index (FADI) and Foot posture index (FPI) were recorded preoperatively and postoperatively at 6, 12 weeks and final follow up (range: 6–21 months; mean: 14.2months). Results. Statistically significant improvement was observed in KSS score, WOMAC score, FADI and FPI after TKA. There was improvement in ankle valgus after correction of knee varus deformity. Hind foot changes mainly occured at subtalar joint. Hallux valgus (10 patients), and Pesplanus (5 patients) were associated with advanced osteoarthritis of knee. Gait profile score and Gait deviation index improved significantly after TKA. There was increased stance phase and decreased stride length in knee osteoarthritis patients which improved after TKA. Conclusion. Hind foot malalignment with foot deformities (hind foot valgus) occur secondary to knee malalignment and deformities (varus deformity) in advanced osteoarthritis of knee which subsequently improve following TKA

Introduction. Limb deformity is usually assessed clinically assisted by long leg alignment radiographs and further imaging modalities (MRI and CT). Often decisions are made based on static imaging and simple gait interpretation in clinic. We have assessed the value of gait lab analysis in surgical decision making comparing surgical planning pre and post gait lab assessment. Materials & Methods. Patients were identified from the local limb reconstruction database. Patients were reviewed in the outpatient clinic and long leg alignment radiographs and a CT rotational limb profile were performed. A surgical plan was formulated and documented. All patients then underwent a formal gait lab analysis. The gait lab recommendations were then compared to the initial plan. Results. Twelve patients (8 female) with mean age of 14 (range 12–16) were identified. Nine were developmental torsional malalignments, one arthrogryposis, one hemiparesis secondary to spinal tumour resection and one syndromic limb deficiency. The gait lab recommended conservative management in four patients and agreed with eight surgical plans with one osteotomy level changing. Five patients are post-operative: two bilateral distal tibial osteotomies, two de-rotational femoral osteotomy with de-rotational tibial osteotomies and one bilateral femoral de-rotational osteotomies. Conclusions. Limb deformity correction is major surgery with long rehabilitation and recovery period. Gait lab analysis can identify who would benefit from conservative management rather than surgery with our study showing changes to surgical planning in one third of patients. The gait lab analysis helps to identify patients with functional and neuromuscular imbalances where correcting the bony anatomy may not actually benefit the patient

Introduction & Aim. During TKR it is mandatory to achieve perfect soft tissue balance and component alignment. It is necessary to access all tight structures for proper releases. We aim to analyze the results of Trivector arthrotomy approach for TKRs. Methods. It is a retrospective study of 1050 cases between 2010-2020. All cases were performed by a single surgeon. Approach includes dividing distal 30% of vastus medialis along with medial retinaculum - 1cm medial to patella and patellar tendon distally up to Tibial tuberosity and raised as a single flap. Results. 656 cases Varus + FFD, 305 Varus, 60 Valgus, 24 hyperextension deformity & 5 neutral alignment cases were included. Results showed 87% patients at postop day-1 and 96% by day-4 regained ability to perform unassisted SLR. 4% had 5-to-10-degree quadriceps lag at discharge & recovered to neutral by 4 weeks. The surgical field was adequate in all cases. KSS score improved from Pre op of 56 (38-71) to a post op of 89 (84-95). All patients by day 10 were walking unaided or with a single cane in case of Bilateral TKRs. Medial parapatellar arthrotomy divides the quadriceps tendon. The alteration in various vectors of Quadriceps can change the balance and laterally mal-track the patella. Incidence of Lateral release is higher with this. Mid and subvastus approaches are non-extensile and have poor visibility during surgery increasing risk of malalignment. Trivector arthrotomy is extensile and retains 70% strength of vastus medialis. At closure, the quads mechanism is perfectly aligned, reducing the incidence of lateral mal-tracking and lateral release. Conclusion. The extensile nature of the approach and minimal disruption of the quadriceps mechanism encourages us to use this approach for all cases. It is a true “Gateway.”

Tibiotalocalcaneal arthrodesis (TTCA) is a salvage procedure to functionally block the ankle and subtalar joints to treat severe ankle and hindfoot disease. Complication rates range between 20-40%, with below-knee amputation rate 1.5-19%. The heterogeneous patient cohort and indication(s) for surgery make post-operative outcomes difficult to predict. Consulting patients about potential pain and functional outcomes is difficult. When researching this area commonly, PROM data is used, less frequently functional objective measures like the 2-minute-walk-test (2MWT) are used. The aim was to compare the PROMs and objective outcomes between patients who underwent TTCA and BKA. Fifty-two patients underwent a TTCA using an intramedullary hindfoot nail. Indications for TTCA, post-traumatic OA, failed arthrodesis and malalignment. These patients were compared to 11 patients who underwent unilateral below knee amputation (BKA) due to trauma. Outcomes measures PROMs AOFAS ankle hindfoot scale and Shor-Form 36 (SF-36). Objective measures; 2MWT, Timed-up-and-go (TUG). Mean age TTCA 55.9, BKA 46.4. Average follow-up time 53 months. TTCA group had average 6.3 operations prior to arthrodesis (range 1-23). Of the TTCA group two ankles did not unite (7%), all complication rate 35%, 18% reported no pain. A significant negative correlation was demonstrated between the clinical outcome and the number of surgeries prior to the TTCA. TUG and 2MWT had significantly (p<0.05) better outcomes for the BKA group compared to TTCA. SF-36 BKA patients scored higher than the TTCA patients on physical functioning (p<0.01) and mental health (p<0.05) subscales as well as the mental component score (p<0.05). This study gives clinicians evidence about the natural history of hindfoot arthrodesis and functional outcomes from BKA. Hopefully this study will improve evidence to help patients and surgeons make decisions about expected surgical outcomes from TTCA and BKA procedures

Malalignment is a common complication following tibial surgery, occurring in 10% of fractures. This is associated with prolonged healing time and non-union. It occurs due to inability to maintain a satisfactory reduction. A reduction device, such as the Staffordshire Orthopaedic Reduction Machine (STORM), permits the surgeon to manipulate the fracture and hold it reduced. A retrospective parallel case series was undertaken of all patients undergoing tibial nails over a six-year period from 2014 to 2021. Patient demographics were obtained from medical records. Operative times obtained from the theatre IT system and included the time patient entered theatre and surgical start and finish times for each case. Anteroposterior and lateral long leg post-operative radiographs were reviewed. Angulation was measured in both coronal and sagittal planes, by two separate orthopaedic surgeons. A reduction was classified to be ‘mal-aligned’ if the angle measured was greater than 5 degrees. One tailed unpaired t-test was used to compare alignment in each plane. Bony union was assessed on subsequent radiographs and was determined according to the Radiographic Union Score for Tibial Fractures. 31 patients underwent tibial nail during the time period. 8 patients were lost to follow up and were excluded. Of the remaining 23 patients, the STORM device was utilised in 11. The overall mean alignment was acceptable across all groups at 2.17° in the coronal plane and 2.56° in the saggital plane. Analysing each group individually demonstrated an improved alignment when STORM was utilised: 1.7° (1°–3°) vs 2.54° (0°–5°) for the coronal plane and 1.6° (0°–3°) vs 3.31° (0°–9°) in the saggital plane. This difference was significant in saggital alignment (p=0.03) and showed a positive trend in coronal alignment, although was not significant (p=0.08). The time in theatre was shorter in the control group with a mean of 113 minutes (65 to 219) in comparison to STORM with a mean of 140 minutes (105 to 180), an increased theatre time of 27 minutes (p=0.04). This study demonstrates that STORM can be used in the surgical treatment of tibial fractures resulting in improved fracture alignment with a modest increase in theatre time

Constrained implants with intra-medullary fixation are expedient for complex TKA. Constraint is associated with loosening, but can correction of deformity mitigate risk of loosening?. Primary TKA's with a non-linked constrained prosthesis from 2010-2018 were identified. Indications were ligamentous instability or intra-medullary fixation to bypass stress risers. All included fully cemented 30mm stem extensions on tibia and femur. If soft tissue stability was achieved, a posterior stabilized (PS) tibial insert was selected. Pre and post TKA full length radiographs showed. i. hip-knee-ankle angles (HKAA). ii. Kennedy Zone (KZ) where hip to ankle vector crosses knee joint. 77 TKA's in 68 patients, average age 69.3 years (41-89.5) with OA (65%) post-trauma (24.5%) and inflammatory arthropathy (10.5%). Pre-op radiographs (62 knees) showed varus in 37.0%. (HKAA: 4. o. -29. o. ), valgus in 59.6% (HKAA range 8. o. -41. o. ) and 2 knees in neutral. 13 cases deceased within 2 years were excluded. Six with 2 year follow up pending have not been revised. Mean follow-up is 6.1 yrs (2.4-11.9yrs). Long post-op radiographs showed 34 (57.6%) in central KZ (HKKA 180. o. +/- 2. o. ). . Thirteen (22.0%) were in mechanical varus (HKAA 3. o. -15. o. ) and 12 (20.3%) in mechanical valgus: HKAA (171. o. -178. o. ). Three failed with infection; 2 after ORIF and one with BMI>50. The greatest post op varus suffered peri-prosthetic fracture. There was no aseptic loosening or instability. Only full-length radiographs accurately measure alignment and very few similar studies exist. No cases failed by loosening or instability, but PPF followed persistent malalignment. Infection complicated prior ORIF and elevated BMI. This does not endorse indiscriminate use of mechanically constrained knee prostheses. Lower demand patients with complex arthropathy, especially severe deformity, benefit from fully cemented, non-linked constrained prostheses, with intra-medullary fixation. Hinges are not necessarily indicated, and rotational constraint does not lead to loosening

Introduction. Intraoperative assessment of coronal alignment is important when performing corrective osteotomies around the knee and ankle, limb lengthening and trauma surgery. The Joint Angle Tool (JAT) provides surgeons with information about the anatomic and mechanical axes intraoperatively based on true anteroposterior radiographs. Aim: Presentation of the JAT, a low-cost goniometer for intraoperative assessment of the lower limb alignment. Materials and Methods. The JAT consists of pre-printed joint orientation angles of the anatomic and mechanical axis including normal variations on a plastic sheet. It is placed on the screen of the image intensifier after obtaining a true anterior-posterior image. The pre-printed joint orientation angles can intraoperatively assist the surgeons in achieving the pre-planned axis correction. Here, its feasibility is demonstrated in four cases. Results. Here, we present the intraoperative use of JAT in four cases:. 77 mm femoral bone transport due to non-union utilizing a bone transport nail,. distal femoral osteotomy correcting coronal and torsional malalignment using a retrograde intramedullary trauma nail,. proximal / high tibial open wedge osteotomy with an intramedullary implant correcting varus malalignment in a hypophosphatemic rickets patient, and. a supramalleolar, closing wedge osteotomy realigning the anatomic axis with a plate and screws. Conclusions. The JAT is a modified goniometer which allows intraoperative assessment of the mechanical and anatomic axis. JAT is applicable throughout the entire surgical procedure irrespective of the method of internal fixation and may provide additional reassurance of correct alignment. The JAT consists of a plastic sheet with printed joint orientation angles and their normal variation. JAT is freely available from . profeedback.dk/JAT/JAT.pdf. for use and modification according to Creative Commons license (CC BY-SA 4.0)

Introduction. Active robotics for total knee Arthroplasty (TKA) uses a CAD-CAM approach to plan the correct size and placement of implants and to surgically achieve planned limb alignment. The TSolution One Total Knee Application (THINK Surgical Inc., Fremont, CA) is an open-implant platform, CT-based active robotic surgical system. A multi-center, prospective, non-randomized clinical trial was performed to evaluate safety and effectiveness of robotic-assisted TKA using the TSolution One Total Knee Application. This report details the findings from the IDE. Methods. Patients had to be ≥ 21 years old with BMI ≤ 40, Kellgren-Lawrence Grade ≥ 3, coronal deformity ≤ 20°, and sagital flexion contracture ≤ 15° to participate. In addition to monitoring all adverse events (AE), a pre-defined list of relevant major AEs (medial collateral ligament injury, extensor mechanism disruption, neural deficit, periprosthetic fracture, patellofemoral dislocation, tibiofemoral dislocation, vascular injury) were specifically identified to evaluate safety. Bleeding complications were also assessed. Malalignment rate, defined as the percentage of patients with more than a ± 3° difference in varus-valgus alignment from the preoperative plan, was used to determine accuracy of the active robotic system. Knee Society Scores (KSS) and Short Form 12 (SF-12) Health Surveys were assessed as clinical outcome measures. Results were compared to published values associated with manual TKA. Results. A total of 115 patients were enrolled at 6 US centers and followed for a maximum of 12 months after surgery. Mean surgical time (incision to close) improved consistently as the technique evolved (first 10 cases = 131.5 min, first 20 cases = 122.4 min), with mean robot time = 45.8 min. The incidence of pre-defined AEs identified was 0%, serving as a measure of safety of the procedure. Outside of the pre-defined list, only one AE was definitely associated with the use of the device; a metal tack was left inside the knee joint but no reoperation was performed. No patients required a blood transfusion. Alignment outside of the ± 3° goal was 11.2% with a difference of 0.5° ± 1.9° (mean ± STD), which represents a 43% statistically significant (posterior probability > 0.95) reduction in malalignment compared to the literature. Mean KSS Functional scores improved from 40.2 at baseline to 65.4 at 3 months, mean KSS Objective scores improved from 46.9 to 71.2, mean KSS Patient Satisfaction scores improved from 14.5 to 30.6, and mean SF-12 Physical Component scores improved from 32.9 to 43.5. Discussion. The TSolution One Total Knee Application is descended from an active robotic system used in >8000 cases outside the United States since 2002. This trial represents the first US based study of this technology for primary TKA. The clinical study demonstrated positive safety outcomes as none of the seven pre-defined AEs were observed and there were no cases requiring transfusion. A positive effectiveness outcome was also demonstrated as the malalignment rate found in this study showed a substantial reduction from the 32% malalignment rate published in the literature for conventional instruments. KSS and SF-12 scores were comparable to other published TKA series. For any figures or tables, please contact authors directly

The use of shorter humeral stems in reverse shoulder arthroplasty has been reported as safe and effective. Shorter stems are purported to be bone preserving, easy to revise, and have reduced surgical time. However, a frequent radiographic finding with the use of uncemented short stems is stress shielding. Smaller stem diameters reduce stress shielding, however, carry the risk of varus or valgus malalignment in the metadiaphyseal region of the proximal humerus. The aim of this retrospective radiographic study was to measure the true post-operative neck-shaft (N-S) angle of a curved short stem with a recommended implantation angle of 145°. True anteroposterior radiographs of patients who received RTSA using an Ascend Flex short stem at three specialized shoulder centres (London, ON, Canada, Lyon, France, Munich, Germany) were reviewed. Radiographs that showed the uncemented stem and humeral tray in orthogonal view without rotation were included. Sixteen patients with proximal humeral fractures or revision surgeries were excluded. This yielded a cohort of 124 implant cases for analysis (122 patients, 42 male, 80 female) at a mean age of 74 years (range, 48 – 91 years). The indications for RTSA were rotator cuff deficient shoulders (cuff tear arthropathy, massive cuff tears, osteoarthritis with cuff insufficiency) in 78 patients (63%), primary osteoarthritis in 41 (33%), and rheumatoid arthritis in 5 (4%). The humeral component longitudinal axis was measured in degrees and defined as neutral if the value fell within ±5° of the humeral axis. Angle values >5° and < 5 ° were defined as valgus and varus, respectively. The filling-ratio of the implant within the humeral shaft was measured at the level of the metaphysis (FRmet) and diaphysis (FRdia). Measurements were conducted by two independent examiners (SA and TW). To test for conformity of observers, the intraclass correlation coefficient (ICC) was calculated. The inter- and intra-observer reliability was excellent (ICC = 0.965, 95% confidence interval [CI], 0.911– 0.986). The average difference between the humeral shaft axis and the humeral component longitudinal axis was 3.8° ± 2.8° (range, 0.2° – 13.2°) corresponding to a true mean N-S angle of 149° ± 3° in valgus. Stem axis was neutral in 70% (n=90) of implants. Of the 34 malaligned implants, 82% (n=28) were in valgus (mean N-S angle 153° ± 2°) and 18% (n=6) in varus position (mean N-S angle 139° ± 1°). The average FRmet and FRdiawere 0.68 ± 0.11 and 0.72 ± 0.11, respectively. No association was found between stem diameter and filling ratios (FRmet, FRdia) or cortical contact with the stem (r = 0.39). Operative technique and implant design affect the ultimate positioning of the implant in the proximal humerus. This study has shown, that in uncemented short stem implants, neutral axial alignment was achieved in 70% of cases, while the majority of malaligned humeral components (86%) were implanted in valgus, corresponding to a greater than 145° neck shaft angle of the implant. It is important for surgeons to understand that axial malalignment of a short stem implant does influence the true neck shaft angle

Background. Authors sought to determine the degree of lateral condylar hypoplasia of distal femur was related to degree of valgus malalignment of lower extremity in patients who underwent TKA. Authors also examined the relationships between degree of valgus malalignment and degree of femoral anteversion or tibial torsion. Methods. This retrospective study included 211 patients (422 lower extremities). Alignment of lower extremity was determined using mechanical tibiofemoral angle (mTFA) measured from standing full-limb AP radiography. mTFA was described positive value when it was valgus. Patients were divided into three groups by mTFA; more than 3 degrees of valgus (valgus group, n = 31), between 3 degrees of valgus to 3 degrees of varus (neutral group, n = 78), and more than 3 degrees of varus (varus group, n = 313). Condylar twisting angle (CTA) was used to measure degree of the lateral femoral condylar hypoplasia. CTA was defined as the angle between clinical transepicondylar axis (TEA) and posterior condylar axis (PCA). Femoral anteversion was measured by two methods. One was the angle formed between the line intersecting femoral neck and the PCA (pFeAV). The other was the angle formed between the line intersecting femoral neck and clinical TEA (tFeAV). Tibial torsion was defined as a degree of torsion of distal tibia relative to proximal tibia. It was determined by the angle formed between the line connecting posterior cortices of proximal tibial condyles and the line connecting the most prominent points of lateral and medial malleolus. Positive values represented relative external rotation. Negative values represented relative internal rotation. Results. Greater lateral femoral condylar hypoplasia was related to increased valgus alignment of lower extremity. Correlation coefficient between mTFA and CTA was 0.253 (p < 0.001). Valgus group showed increased CTA, which was 10.2° ± 1.9°. CTA was 7.4° ± 2.5° in neutral group and 6.6° ± 4.8° in varus group. There was significant positive correlation between the degree of valgus alignment and the degree of femoral anteversion (r = 0.145, p = 0.003). pFeAV was 16.7° ± 5.8° in valgus group, 12.1° ± 6.0° in neutral group and 10.9° ± 7.0° in varus group. There was no correlation between degree of valgus alignment and degree of femoral anteversion (r = 0.060, p = 0.218). In terms of tibial torsion, increased valgus malalignment was associated with increased tibial torsion (r = 0.374, p < 0.001). Valgus group showed increased tibial torsion than other groups. Tibial torsion was 32.6° ± 6.2° in valgus group, 26.3° ± 6.9° in neutral group and 22.6° ± 7.2° in varus group. Conclusions. Increased valgus alignment of lower extremity was related to greater lateral femoral condylar hypoplasia. However, increased valgus alignment was not related to degree of femoral anteversion whereas it was related to increased external tibial torsion. Our findings should be considered when determining proper rotational alignment in TKA

INTRODUCTION. To test whether there are differences in postoperative mechanical and component alignment, and in functional results, between conventional, navigated and patient-specific total knee arthroplasties in a low-volume centre?. MATERIAL AND METHODS. Retrospective cohort study of 391 patients who received conventional, navigated or patient- specific primary cemented TKA in a low-volume hospital. RESULTS. The risk of mechanical alignment outliers was 89% lower in the navigated group compared to the conventional TKA group. There was a 63% lower risk of femoral component malalignment and a 66% lower risk of tibial component malalignment in the navigated group. No significant reduction in the risk of malalignment was seen in the patient-specific group. Total WOMAC and Oxford scores were no different between the three techniques. The patient-specific group reported better WOMAC pain scores. PSI TKA was 33% more expensive than conventional TKA and 28% more expensive than Navigated TKA. DISCUSSION. Navigated TKA improved alignment, but neither navigated nor patient-specific TKA improved functional outcomes. Patient-specific TKA was more expensive, with little additional benefit. Clinical relevance: The routine use of patient-specific instrumentation in low-volume centers is not supported by the currently available data

Background. Coronal malalignment has been proposed as a risk factor for mechanical failure after total knee arthroplasty (TKA). In response to these concerns, technologies that provide intraoperative feedback to the surgeon about component positioning have been developed with the goal of reducing rates of coronal plane malalignment and improving TKA longevity. Imageless hand-held portable accelerometer technology has been developed to address some the limitations associated with other computer assisted navigation devices including line-of-sight problems, preoperative imaging requirements, extra pin sites, up-font capital expenditures, and learning curve. The purpose of this study was to compare the accuracy and precision of a hand-held portable navigation system versus conventional instrumentation for tibial and femoral resections in TKA. Methods. This study was a single-surgeon, retrospective cohort study. Consecutive patients undergoing TKA were divided into three groups: 1) tibial and femoral resections performed with conventional intra- and extramedullary resection guides (CON group; N=84), 2) a hand-held portable navigation system (KneeAlign, OrthoAlign Inc, Aliso Viejo, CA) for tibial resection only (TIBIA group; N=78), and 3) navigation for both tibial and distal femoral resections (BOTH group; N=80). Postoperative coronal alignment of the distal femoral and proximal tibial resection were measured based on the anatomic axis from standing AP radiographs and compared between the three groups for both precision and accuracy. Malalignment was considered to be greater than 3° varus/valgus from expected resection angle. Results. Preoperative age, sex, and knee axis alignment were similar between the three groups. Mean postoperative alignment of the distal femoral resection, proximal tibial resection, and knee axis did not differ between groups (Figure 1). Increased frequencies of malalignment (±3° varus/valgus) of the femoral resection (24% CON versus 5% TIBIA and 8% BOTH; p<0.001) and knee axis (31% CON versus 8% TIBIA and 6% BOTH; p<0.001) were observed with conventional resection guides compared to both navigation groups. Conclusion. Use of a hand-held portable navigation system improved precision of the distal femoral resection and overall anatomical knee alignment after TKA

Introduction. Persistent patellofemoral (PF) pain is a common postoperative complication after total knee arthroplasty (TKA). In the USA, patella resurfacing is conducted in more than 80% of primary TKAs [1], and is, therefore, an important factor during surgery. Studies have revealed that the position of the patellar component is still controversially discussed [2–4]. However, only a limited number of studies address the biomechanical impact of patellar component malalignment on PF dynamics [2]. Hence, the purpose of our present study was to analyze the effect of patellar component positioning on PF dynamics by means of musculoskeletal multibody simulation in which a detailed knee joint model resembled the loading of an unconstrained cruciate-retaining (CR) total knee replacement (TKR) with dome patella button. Material and Methods. Our musculoskeletal multibody model simulation of a dynamic squat motion bases on the SimTK data set (male, 88 years, 66.7 kg) [5] and was implemented in the multibody dynamics software SIMPACK (V9.7, Dassault Systèmes Deutschland GmbH, Gilching, Germany). The model served as a reference for our parameter analyses on the impact on the patellar surfacing, as it resembles an unconstrained CR-TKR (P.F.C. Sigma, DePuy Synthes, Warsaw, IN) while offering the opportunity for experimental validation on the basis of instrumented implant components [5]. Relevant ligaments and muscle structures were considered within the model. Muscle forces were calculated using a variant of the computed muscle control algorithm. PF and tibiofemoral (TF) joints were modeled with six degrees of freedom by implementing a polygon-contact model, enabling roll-glide kinematics. Relative to the reference model, we analyzed six patellar component alignments: superior-inferior position, mediolateral position, patella spin, patella tilt, flexion-extension and thickness. The effect of each configuration was evaluated by taking the root-mean-square error (RMSE) of the PF contact force, patellar shift and patellar tilt with respect to the reference model along knee flexion angle. Results. The analysis showed that the PF contact force was mostly affected by patellar component thickness (RMSE=440 N) as well as superior-inferior (RMSE=199 N), and mediolateral (RMSE=98 N) positioning.. PF kinematics was mostly affected by mediolateral positioning, patellar component thickness, and superior-inferior positioning. Medialization of the patellar component reduced the peak PF contact force and caused a lateral patellar shift. Discussion. Based on our findings, we conclude that malalignment in mediolateral and superior-inferior direction, tilt and thickness of patellar resurfacing are the most important intraoperative parameters to affect PF dynamics. It could be shown that the translational positioning is more critical than rotational positioning regarding PF contact force. Reported findings are in good agreement with previous experimental and clinical studies [2–4]. Our data reveal that patellar component positioning has to be aligned precisely during total knee arthroplasty to prevent postoperative complications. For any figures or tables, please contact authors directly