Femoral Resection Research Articles

Исследование напряженно-деформированного состояния в системе «имплантат — кость» на модели алокомпозитного эндопротеза проксимального отдела бедренной кости

Актуальность. Восстановление массивных послерезекционных дефектов длинных костей — одна из основных задач, которая стоит перед хирургом при лечении больных с опухолевыми поражениями костей. Поэтому разработка оптимальных имплантатов для замещения дефектов костей и суставов продолжается уже многие десятилетия. Для подбора идеального имплантата, который должен соответствовать требованиям биосовместимости, механической стабильности и быть безопасным, нужно проводить множество различных исследований и тестов. Именно метод алокомпозитного эндопротезирования представляет интерес для углубленного проведения исследований. Цель: обосновать методику алокомпозитного эндопротезирования на основании математического моделирования методом конечных элементов. Материалы и методы. Проведено изучение методом конечных элементов математической модели бедренной кости с «опухолевым» эндопротезом. Изучено напряженно-деформированное состояние модели при выполнении резекции бедренной кости прямым сечением и сечением в виде ступеньки. Смоделирована ситуация в разные сроки после оперативного вмешательства — через 3 и 6 месяцев. Для каждого типа резекции моделировали цементный и бесцементный варианты фиксирования ножки эндопротеза. Результаты. При поперечной остеотомии и бесцементном способе фиксации ножки максимальные по величине напряжения (92,3 МПа) возникают в зоне остеотомии. В диафизарной части бедренной кости зона максимальных напряжений располагается по медиальной стороне, они принимают значения 10,5 и 10,1 МПа в дистальной и проксимальной частях соответственно. Использование ступенчатой остеотомии в сочетании с бесцементной фиксацией ножки эндопротеза в ближайший послеоперационный период позволяет снизить уровень напряжений в зоне остеотомии до 59,1 МПа. В процессе увеличения прочности костного регенерата после использования поперечной остеотомии в сочетании с бесцементной фиксацией ножки наблюдается снижение уровня напряжений в зоне остеотомии — 75,6 МПа. В диафизарной части бедренной кости они определяются в пределах от 9,5 до 10,0 МПа. При использовании ступенчатой остеотомии и бесцементного крепления ножки эндопротеза диапазон напряжений в диафизарной части бедренной кости определяется от 7,9 до 13,8 МПа. Использование цемента в сочетании с поперечной остеотомией в послеоперационный период 3 месяца не ведет к принципиальным изменениям в напряженно-деформированном состоянии модели. Максимальная величина напряжений (77,1 МПа) определяется в зоне остеотомии. При использовании ступенчатой остеотомии наличие цементного слоя между ножкой эндопротеза и стенкой костно-мозгового канала позволяет снизить уровень напряжений в зоне остеотомии до отметки 31,5 МПа. Выводы. В результате проведенного математического моделирования обнаружено, что выполнение ступенчатой остеотомии бедренной кости позволяет вдвое снизить уровень механических напряжений в зоне остеотомии по сравнению с моделями с поперечной остеотомией. Использование костного цемента для фиксации ножки эндопротеза в теоретической модели также позволяет значительно снизить уровень напряжений во всех вариантах исследованных моделей за счет образования демпферного слоя между металлом и костной тканью. Увеличение прочности костного регенерата со временем приводит к выравниванию величин напряжений как между контрольными точками каждой из моделей, так и между моделями с различными видами остеотомии бедренной кости.

Resection of the proximal femur during one-stage revision for infected hip arthroplasty : risk factors and effectiveness.

One-stage revision hip arthroplasty for periprosthetic joint infection (PJI) has several advantages; however, resection of the proximal femur might be necessary to achieve higher success rates. We investigated the risk factors for resection and re-revisions, and assessed complications and subsequent re-revisions. In this single-centre, case-control study, 57 patients who underwent one-stage revision arthroplasty for PJI of the hip and required resection of the proximal femur between 2009 and 2018 were identified. The control group consisted of 57 patients undergoing one-stage revision without bony resection. Logistic regression analysis was performed to identify any correlation with resection and the risk factors for re-revisions. Rates of all-causes re-revision, reinfection, and instability were compared between groups. Patients who required resection of the proximal femur were found to have a higher all-cause re-revision rate (29.8% vs 10.5%; p = 0.018), largely due to reinfection (15.8% vs 0%; p = 0.003), and dislocation (8.8% vs 10.5%; p = 0.762), and showed higher rate of in-hospital wound haematoma requiring aspiration or evacuation (p = 0.013), and wound revision (p = 0.008). The use of of dual mobility components/constrained liner in the resection group was higher than that of controls (94.7% vs 36.8%; p < 0.001). The presence and removal of additional metal hardware (odds ratio (OR) = 7.2), a sinus tract (OR 4), ten years' time interval between primary implantation and index infection (OR 3.3), and previous hip revision (OR 1.4) increased the risk of proximal femoral resection. A sinus tract (OR 9.2) and postoperative dislocation (OR 281.4) were associated with increased risk of subsequent re-revisions. Proximal femoral resection during one-stage revision hip arthroplasty for PJI may be required to reduce the risk of of recurrent or further infection. Patients with additional metalware needing removal or transcortical sinus tracts and chronic osteomyelitis are particularly at higher risk of needing proximal femoral excision. However, radical resection is associated with higher surgical complications and increased re-revision rates. The use of constrained acetabular liners and dual mobility components maintained an acceptable dislocation rate. These results, including identified risk factors, may aid in preoperative planning, patient consultation and consent, and intraoperative decision-making. Cite this article: Bone Joint J2021;103-B(11):1678-1685.

The Wagner Modular (S2) Prosthesis for Proximal Femur Bone Loss ; Prospective Study of 19 Cases

Background: Wagner proximal femur prosthesis is the versatile modular implant. Study Design: Prospective study Setting: Department of Orthopaedic Surgery Dow University of Health Sciences / Civil Hospital Karachi, from January 2013 to December 2019. Methodology: Total 19 patients of both genders with proximal femur bone loss due to tumor, implant failure for proximal femur fixation, comminuted intertrochanteric fracture, and failed arthroplasty included in the study. After taking written informed consent, detailed demographics including age, gender, indication of wagner prosthesis, and wagner stem type were recorded. Among all the patients 11 patients received total hip replacement and 8 patients received bipolar. Complications associated with procedure were recorded. Outcomes were assessed by Merle D Aubgine scale. Results: Total 19 patients were included in the study who were operated with wagner prosthesis for proximal femur bone deficit problems. 7 (37%) patients were male and 12 (67%) were female , between age of 16 to 70. 13 (68%) patient have proximal femur problem on right side and 6(32%) patient on left side .10 Patient have proximal femur fixation problems and 9 with proximal femur tumor. Modular wagner prosthesis used in all patients . Per-operative one (5%) patient have perforation of cortex and One (5%)patient posterior hip dislocation on next day . Two (11%) patient had per-operative fracture . Maximum follow-up is from 6.3 years to minimum 6 months. One patient with metastasis died within four weeks of surgery. Outcome measured with modified Merle D Aubgine scale showed no excellent , good in 15(79%) , fair 3 (16%), poor 1(5%). Conclusion: Wagner proximal femur modular implant is a versatile implant for proximal femur fixation failure and after proximal femur resection in tumor patients. It is modular with variable options to make stable hip joint. It is cheap as comparative to proximal femur replacement implant for tumor. Keywords: Implant failure, Proximal femur, Tumor, Wagner implant.

3D Geometric Shape Reconstruction for Revision TKA and UKA Knees Using Gaussian Process Regression.

Revision knee surgery is complicated by distortion of previous components and removal of additional bone, potentially causing misalignment and inappropriate selection of implants. In this study, we reconstructed the native femoral and tibial surface shapes in simulated total/unicompartmental knee arthroplasty (TKA/UKA) for 20 femurs and 20 tibias using a statistical inference methodbased on Gaussian Process regression. Compared to the true geometry, the average absolute errors (mean absolute distances) in the prediction of resected femur bones in TKA, medial UKA, and lateral UKA were 1.0 ± 0.3 mm, 1.0 ± 0.3 mm, and 0.8 ± 0.2 mm, respectively, while those in the prediction of tibia resections in the corresponding surgeries were 1.0 ± 0.4 mm, 0.8 ± 0.2 mm, and 0.7 ± 0.2 mm, respectively. Furthermore, it was found that the prediction accuracy depends on the size and gender of the resected bone. For example, the prediction accuracy for UKA cuts was significantly better than that for TKA cuts (p < 0.05). The female and male cuts were often overfit and underfit, respectively. The data indicated that this reconstruction approach can be a viable option for planning of revision surgeries, especially when contralateral anatomy is pathological or cannot be available.

Endoprosthetic Proximal Femoral Hemiarthroplasty Versus Total Hip Endoprosthetic Reconstruction After Proximal Femoral Resections in Young Adults

Abstract Background Metastatic tumors are the most common malignant lesion of the proximal femur, with carcinomas being the most frequent. The proximal femur and midfemur are common sites for primary bone sarcomas; approximately16% of Ewing's sarcomas, 13% chondrosarcomas and 10% of osteosarcomas develop at these locations. The major aim in the management of patients who have bone malignancies is prolonging their survival. Primary bone sarcomas that require surgical resection can be treated by either amputation or limb salvage. Most studies which compared both approaches reported that limb salvage had no adverse effect on patients’ survival on long-term. Objective This is a systematic review of literature with meta-analysis study that compare the functional outcomes and complications of the methods; proximal femoral hemi versus total arthroplasty after proximal femur resection followed by endoprosthetic reconstruction and provide recommendations by the best available evidence. Methods We included Randomized control trails (RCTs), including cluster RCTs, controlled (non-randomized) clinical trials or cluster trials, prospective and retrospective comparative cohort studies, and case-control or nested case-control studies and controlled clinical trials. We excluded cross-sectional studies, case reports, review articles, letters to the editor, meeting abstracts, and technique papers. Search results conducted to systematic review management software and manually screened for eligibility were included. Critical appraisal checklist was used to assess the search results based on the inclusion/exclusion criteria. Results Twenty-three studies are included. Quality appraisal demonstrated that all but one study is retrospective. The pooled results from the meta-analysis showed that the rate of aseptic loosening was only 2% when reconstruction occurs with endoprosthetic proximal femoral hemiarthroplasty. There was unimportant heterogeneity in the included studies. The rate of conversion to total hip arthroplasty (THA) is 4.6% to 8% of oncological patients. The rate of periprosthetic fracture was only 1% Conclusion Proximal femoral endoprosthesis has definitive benefits in the treatment of primary or metastatic tumors affecting the proximal femur. The implants tend to improve the function and quality of life of patients with metastatic disease and high-grade localized disease. It also provides them with a relatively pain-free limb with good functional capacity. With continuing advances in the surgical and oncological fields, there is a great potential for curative limb salvage surgery in the long term. Reconstruction with endoprosthetic Proximal femoral hemiarthroplasty after proximal femoral resection in young adults can confer additional stability with a reduced dislocation rates and systemic complications as compared to total hip arthroplasty.

Total Femoral Replacement for Complicated Echinococcus Infection: Sixteen-Year Follow-up.

Osseous hydatidosis caused by Echinococcus is rare, especially in long bones. To the best of our knowledge, this is the third femoral hydatidosis case with successful osseous eradication through total femoral resection and total femoral megaprosthesis. Unlike the previous 2 cases, we uniquely illustrate recurrent soft-tissue hydatidosis episodes requiring additional hydatid resections for local control with no evidence of disease at final 16-year follow-up, the longest follow-up period of the 3 reported cases. Despite radical bone resection for osseous hydatidosis eradication, additional complex surgical interventions may be needed to locally control soft-tissue disease.

Long-term competing risks for overall and cause-specific failure of rotating-hinge distal femoral arthroplasty for tumour reconstruction

Rotating-hinge knee prostheses are commonly used to reconstruct the distal femur after resection of a tumour, despite the projected long-term burden of reoperation due to complications. Few studies have examined the factors that influence their failure and none, to our knowledge, have used competing risk models to do so. The purpose of this study was to determine the risk factors for failure of a rotating-hinge knee distal femoral arthroplasty using the Fine-Gray competing risk model. We retrospectively reviewed 209 consecutive patients who, between 1991 and 2016, had undergone resection of the distal femur for tumour and reconstruction using a rotating-hinge knee prosthesis. The study endpoint was failure of the prosthesis, defined as removal of the femoral component, the tibial component, or the bone-implant fixation; major revision (exchange of the femoral component, tibial component, or the bone-implant fixation); or amputation. Multivariate Fine-Gray regression analyses revealed different hazards for each Henderson failure mode: percentage of femoral resection (p = 0.001) and extent of quadriceps muscle resection (p = 0.005) for overall prosthetic failure; extent of quadriceps muscle resection (p = 0.002) and fixation of femoral component (p = 0.011) for type 2 failure (aseptic loosening); age (p = 0.009) and percentage of femoral resection (p = 0.019) for type 3 failure (mechanical failure); and type of joint resection (p = 0.037) for type 4 (infection) were independent predictors. A bone stem ratio of > 2.5 reliably predicted aseptic loosening. We identified independent risk factors for overall and cause-specific prosthetic failure after rotating-hinge knee distal femoral arthroplasty using a competing risk Fine-Gray model. A bone stem ratio > 2.5 reliably predicts aseptic loosening. An accurate knowledge of the risks of distal femoral arthroplasty after resection for tumour assists surgical planning and managing patient expectations. Cite this article: Bone Joint J2021;103-B(8):1405-1413.

Component placement accuracy in two generations of handheld robotics-assisted knee arthroplasty.

Total knee arthroplasty (TKA) is the gold standard for treatment of end-stage osteoarthritis. Previous studies have shown that successful outcomes following TKA depend on accurate implant alignment and soft tissue balancing. Robotic-assisted TKA have demonstrated improved accuracy in component placement and have been associated with better outcomes and patient satisfaction. This study aims to report on the execution accuracy of two generations of handheld robotic-assisted surgical systems. This was a retrospective analysis of TKA procedures with two sequential generations of the same handheld robotic-assisted surgical system. Intra-operative data captured included pre-operative limb deformity, limb axes, range of motion, kinematic balance, and the resulting plan for component placement in three-dimensional space. Patients were stratified based on their preoperative coronal lower limb mechanical alignment (> 3° varus, < 3° varus, < 3° valgus, and ≥ 3° valgus). Measurements of component placement (overall lower limb alignment, medial and lateral flexion gaps, and tibial and femoral resection depths) were assessed using descriptive statistics. A total of 435 patients were included and stratified based on preoperative lower limb alignment: 229 with ≥ 3° varus, 78 with varus < 3° and 58 with valgus < 3°, and 70 with valgus > 3°. The mean difference between planned and achieved alignment in the lower limb valgus patients was < 1° across all groups. Mean differences between planned and achieved medial flexion gap was higher in the > 3° subgroup in the varus patient cohort ([< 3°]: 1.15 ± 1.92 vs. [> 3°]: 1.90 ± 2.57); this value was higher in the < 3° subgroup for valgus patients ([< 3°]: 1.34 ± 1.83 vs. [> 3°]: 0.956 ± 1.65). Average resection depth ranged from 9.46 to 10.4mm in the posterior medial femur, 9.25 to 9.95mm in the posterior lateral femur, 7.45 to 8.79mm in the distal medial femur, 8.22 to 9.18mm in the distal lateral femur, 6.70 to 7.07mm in the medial tibial condyle and 6.40 to 7.19mm in the lateral tibial condyle. Non-inferiority testing demonstrated the newer generation is non-inferior to the older generation. Robotic-assisted knee replacement using handheld image-free systems is able to maintain accuracy of component placement. Further investigation of patient reported outcomes as well as long-term implant longevity are needed.

Equal bony resection of distal and posterior femur will lead to flexion/extension gap inequality in robot-assisted cruciate-retaining TKA.

Joint imbalance has become one of the main reasons for early revision after total knee arthroplasty (TKA) and it is directly related to the surgical technique. Therefore, a better understanding of how much bone has to be removed to obtain a balanced flexion/extension gap could improve current practice. The primary objective of this study was to analyse the amount of bone that needed to be removed from the distal and posterior femoral joint surfaces to obtain an equal flexion/extension gap in robot-assisted TKA. The second objective of this study was to evaluate whether the size of the knee joint influenced the amount of bony resection needed to achieve an equal flexion/extension gap in robot-assisted TKA. A retrospective analysis was performed on all patients receiving a robot-assisted TKA (Cruciate Retaining (n = 268)) by six surgeons from April 2018 to September 2019. The robot was used consecutively when available in all patients receiving Cruciate Retaining TKA. Gap assessment, bony resections, femoral implant size and hip-knee-ankle angle were evaluated with the robot. Femoral implant size was categorized into small (size 1-2), medium (size 3-5) and large (size 6-8). The difference between the posterior and distal resection needed to obtain equal flexion and extension gap was on average 2.0mm (SD 1.6) and 1.5mm (SD 2.2) for the medial and lateral compartment, respectively. The discrepancy was smaller in the large implant group compared to the small implant group (p < .05 medial and lateral) and medium implant group (p < .05 medial). Varus knees required a larger differential resection compared to neutral and valgus knees (only laterally) (medial compartment: p < .05 (varus-neutral), p = .051 (varus-valgus); lateral compartment: p < .05 (varus-neutral and varus-valgus). Removing an equal amount of bone from the distal and posterior femur will lead to flexion/extension gap imbalance in TKA. It was required to remove 1.5-2mm more bone from the posterior femur compared to the distal femur to equalize flexion and extension gap. This effect was size dependent: in larger knees, the discrepancy between the distal and posterior resections was smaller. IV.

A new technique for proximal femoral resection in non-ambulatory patients with cerebral palsy

Proximal femoral resection may be proposed to non-ambulatory patients with cerebral palsy and chronic painful hip dislocation. McCarthy's technique confers good results but does not solve the problems related to femoral reascension (bone migration causing painful osseous or cutaneous conflict). We describe a new technique of resection-interposition of the proximal end of the femur which preserves the greater trochanter by an orthogonal osteotomy below the lesser trochanter while maintaining the gluteal-vastus lateralis strut in continuity. A suture of the remaining joint capsule upon itself and a trans-trochanteric capsulodesis are associated to stabilize the cephalic displacement of the femur.

Chondrosarcoma arising in monostotic fibrous dysplasia treated with total femur resection and megaprothesis: A case report.

IntroductionFibrous dysplasia is tumor like lesions of bone which develop as substitution of bone by an expansion of fibrous connective tissue mixed with hard trabeculae. Chondrosarcomas is one of common malignant primary bone tumor derived from heterogenous group of neoplasm producing chondroid matrix. Chondrosarcoma arising in fibrous dysplasia, especially in monostotic fibrous dysplasia is a very rare case.Case reportA 54-year-old male presented with chief complaint of pain on left thigh. Patient with history of pathological fracture on left femoral diaphysis 3 years ago due to fibrous dysplasia and had underwent curettage, open reduction, and internal fixation at other hospital. Plain radiography revealed expansive lytic lesion, interrupted periosteal reaction with plate and screw attached to the lesion, and soft tissue mass. MRI T2FS sequence showed hyperintense mass extending from subtrochanteric to distal of left femoral diaphysis. Histopathological result from biopsy suggested chondrosarcoma.ConclusionsMalignant transformation of monostotic type was less frequently compared to polyostotic type. Among all malignant transformation cases, alteration to chondrosarcoma was more scarce than other malignancy such as osteosarcoma and fibrosarcoma. Wide surgical margin and reconstruction in chondrosarcoma provide good local control and functional outcome.

Comparison with Navigation of a Novel Three-Step Technique for Improving Accuracy of the Distal Femoral Resection during Conventional TKA: A Case-Control Study.

Correct placement of the femoral component in the coronal plane during primary total knee arthroplasty (TKA) is related to long-term survival. The aim of this radiographic study was to determine the accuracy of a novel three-step technique for improving the accuracy of the distal femoral cut during conventional technique and compare it with computer navigation during TKA. A total of 458 TKAs were retrospectively analyzed (178 conventional TKAs with the novel technique and 280 navigated TKAs) for postoperative femoral component coronal alignment and compared between the two groups. Mean femoral component coronal alignment was not significantly different (p = 0.314) between the two groups. There was no significant difference in the mean femoral component coronal alignment between varus and valgus knees. The number of outliers (90 ± 3 degrees) for femoral component coronal alignment was not significantly different between the two groups when assessed separately for varus and valgus deformities. The mean value of femoral component alignment using the conventional technique in knees with varus deformity <10 degrees was 88.8 degrees, in knees with varus deformity 10 to 20 degrees was 89.4 degrees, and in those with varus deformity >20 degrees was 90.2 degrees. Femoral component alignment in knees with varus <10 degrees was significantly different from those >20 degrees (p = 0.006); there was no significant difference between knees with varus <10 degrees and those with 10 to 20 degrees varus (p = 0.251), nor between 10 and 20 degrees varus knees and those with varus >20 degrees (p = 0.116). Using the novel three-step technique during conventional TKA to perform the distal femoral cut can help achieve femoral component coronal alignment comparable to the navigation technique.

Augmented Reality-Assisted Femoral Bone Resection in Total Knee Arthroplasty.

Background:An augmented reality (AR)-based navigation system allows visualization of the center of the femoral head and femoral mechanical axis superimposed on the surgical field during total knee arthroplasty (TKA) and may help surgeons to improve the accuracy of distal femoral resection.Methods:First, we resected 10 femoral Sawbones specimens using the AR-based navigation system and performed computed tomography (CT) to measure the resection angle of the distal part of the femur. We calculated the absolute values of the differences between angles measured using CT images and angles displayed on the smartphone screen of the navigation system. Second, we measured coronal alignment using standing long-leg radiographs for 72 patients undergoing TKA and compared the error in the resection angle between TKA using the AR-based navigation system and that using a conventional intramedullary guide.Results:In the experimental study, the absolute values of the differences between angles measured on CT images and angles displayed using the AR-based navigation system were 0.8° ± 0.5° (range, 0.3° to 1.9°) in the coronal plane and 0.6° ± 0.5° (range, 0.0° to 1.4°) in the sagittal plane. In the clinical study, the mean absolute value of the error in coronal alignment was significantly smaller in the AR-based navigation group than the intramedullary-guide group (1.1° ± 1.0° [range, 0.0° to 3.2°] compared with 2.2° ± 1.6° [range, 0.0° to 5.5°], respectively; 95% confidence interval, 0.5° to 1.8°; p < 0.001).Conclusions:The AR-based navigation system may enable surgeons to perform distal femoral resection more accurately than with the conventional intramedullary guide during TKA.Clinical Relevance:This study validates the use of AR technology to enhance the precision of bone resection in TKA.

Effect of nerve growth factor dimeric mimetic GK-2 on microcirculation in skeletal muscle on the hind limb ischemia model in rats

The purpose of the study. In experiments on a hind limb ischemia model in rats, the effect of the TrkA-receptor agonist of the NGF 4th loop dimeric dipeptide mimetic compound GK-2 has been studied on microcirculation in ischemic skeletal muscle.Methods. the Hind limb ischemia was caused in white male mongrel rats by the femoral artery resection. The compound GK-2 was administered intravenously (1 mg/kg/day during 14 days). Microcirculation parameters were recorded using a computer laser analyzer "LAKK-OP2". Registration was carried out simultaneously in the intact and operated limb before the operation, 1 and 14 days after it.Results. In the conditions of the hind limb ischemia model, it was shown that the compound GK-2 almost completely restored the perfusion index and its variation coefficient in the ischemic muscle to the intact contralateral limb level by the 14th day after surgery.Conclusion. It can be assumed that the anti-ischemic effect of the compound GK-2 is associated with the restoration of microcirculation as a result of increased neoangiogenesis.

Improved accuracy and reproducibility of a novel CT-free robotic surgical assistant for medial unicompartmental knee arthroplasty compared to conventional instrumentation: a cadaveric study.

Alignment errors in medial unicompartmental knee arthroplasty (UKA) predispose to premature implant loosening and polyethylene wear. The purpose of this study was to determine whether a novel CT-free robotic surgical assistant improves the accuracy and reproducibility of bone resections in UKA compared to conventional manual instrumentation. Sixty matched cadaveric limbs received medial UKA with either the ROSA® Partial Knee System or conventional instrumentation. Fifteen board-certified orthopaedic surgeons with no prior experience with this robotic application performed the procedures with the same implant system. Bone resection angles in the coronal, sagittal and transverse planes were determined using optical navigation while resection depth was obtained using calliper measurements. Group comparison was performed using Student's t test (mean absolute error), F test (variance) and Fisher's exact test (% within a value), with significance at p < 0.05. Compared to conventional instrumentation, the accuracy of bone resections with CT-free robotic assistance was significantly improved for all bone resection parameters (p < 0.05), other than distal femoral resection depth, which did not differ significantly. Moreover, the variance was significantly lower (i.e. fewer chances of outliers) for five of seven parameters in the robotic group (p < 0.05). All values in the robotic group had a higher percentage of cases within 2° and 3° of the intraoperative plan. No re-cuts of the proximal tibia were required in the robotic group compared with 40% of cases in the conventional group. The ROSA® Partial Knee System was significantly more accurate, with fewer outliers, compared to conventional instrumentation. The data reported in our current study are comparable to other semiautonomous robotic devices and support the use of this robotic technology for medial UKA. Cadaveric study, Level V.

Clinical outcomes of endoprosthetic reconstruction for proximal femoral resection.

The proximal femur is a common site for primary sarcomas and metastatic lesions. Although the early results of tumor prostheses are promising, the long-term results of reconstruction are unknown. The purpose of this study is to evaluate the prognostic factors affecting prosthesis survival and complications after proximal femoral resection and reconstruction. We reviewed the results of 68 patients who underwent proximal femoral resection and reconstruction with a modular bipolar-type tumor prosthesis between 2005 and 2017. The mean follow-up was 55.6months (range 6-172months). There were 50 male and 18 female patients with a mean age of 41.5years (range 11-80years). Cumulative survival analysis was performed to analyze the risk factors of prosthesis survival. We also evaluated the complications after operation. Fourteen (21%) patients required further surgery at a mean 37months post-operatively (range 5-125months). There were three cases of infection (4%), six of local recurrence (9%), three of acetabular erosion (4%) and two of stem loosening (3%). The implant survival rates were 83.9% at 5years and 59.8% at 10years. Prosthesis survivals did not differ based on fixation method (P=0.085), age (P=0.329) or resection length (P=0.61). Acetabular chondrolysis was identified in 18 (26%) patients and longer resection length (≥20cm) showed a trend for risk of acetabular wear (P=0.132). The results of proximal femoral resection and reconstruction with a modular bipolar-type prosthesis were found to be acceptable with infection and local recurrence as short-term complications and loosening and acetabular erosion as long-term complications.

Oncological and Functional Outcomes in Joint-sparing Resections of the Proximal Femur for Malignant Primary Bone Tumors.

Joint-sparing resections (JSR) of the proximal femur allow for preservation of the proximal femoral growth plate and native hip joint, but whether this offers fewer complications or better function and longevity of the reconstruction remains unknown. In this study, we compared the functional outcomes of pediatric patients with bone sarcomas undergoing JSR of the proximal femur with intercalary allograft (ICA) reconstruction to those undergoing proximal femoral resections (PFR) with allograft-prosthetic composite (APC) reconstructions. We retrospectively reviewed all patients undergoing JSR with ICA reconstruction and PFR with APC reconstructions between 1995 and 2013 at a tertiary pediatric referral center. Primary outcomes included major and minor complications and secondary outcomes included the need for a secondary procedure, presence of local or distant relapse, survival status, and the presence of pain and ambulatory status (limp, assistive device, highest level of function). We assessed differences in outcomes using the Fisher exact and Wilcoxon rank-sum tests. Eight patients underwent a JSR and ICA reconstruction, while 7 patients underwent a PFR with APC reconstruction. Median patient follow-up was 60.4 months (interquartile range: 36.8 to 112.9) Patients undergoing JSR and ICA reconstruction were younger than patients undergoing PFR with APC reconstruction (7.7 vs. 11.7 y, P=0.043); however, we found no other statistically significant differences in patient demographics. There were no statistically significant differences in primary or secondary outcomes between the study groups; however, patients who underwent JSR with ICA had more major complications (62.5% vs. 42.9%, P=0.29) and a lower rate of minor complications (25% vs. 28.6%, P=0.22). Treatment of proximal femoral bone sarcomas in pediatric and adolescent patients remains a challenging enterprise. JSR with ICA reconstruction in the proximal femur, when feasible, may provide a similar function and risk of intermediate-term major and minor complications when compared with PFR with APC reconstruction. Further long-term studies are required to determine the impact of the native femoral head retention with respect to revision rates. Level III, retrospective comparative study.

Is bipolar hemiarthroplasty an appropriate type of hip articulation following proximal femoral or total femoral resections for musculoskeletal malignancies?

Different approaches are applied for reconstruction in patients with a musculoskeletal malignancy which require a proximal femoral or total femoral resection. We aimed to evaluate the treatment outcomes of patients who underwent a proximal femoral or total femoral resection due to bone and soft tissue tumors and had an endoprosthetic reconstruction by a bipolar hemiarthroplasty type of hip articulation. We retrospectively identified 133 patients who underwent a proximal femoral or total femoral endoprosthetic replacement after resection of a bone or soft tissue malignancy. There were 74 male and 59 female patients, with a mean age of 55.02 ± 16.92years (range 11-84years) and a median follow-up of 24.47 ± 24.45months (range 6-164months). Patient demographics, surgical, and oncological data were recorded. Acetabular wear was measured using the classification proposed by Baker. Functional assessment was performed using the Musculoskeletal Tumor Society (MSTS) functional score. There was no statistically significant difference among primary diagnostic groups in terms of gender, prosthesis type, trochanter major resection, local recurrence, complication/revision rate, and MSTS Score (p > 0.05, for each parameter). On the other hand, a statistically significant difference was detected in terms of degree of acetabular erosion among diagnostic groups (p < 0.001); the acetabular erosion rate (AER) was found to be lower in patients with metastatic carcinoma than in patients with a diagnosis of primary bone or soft tissue sarcoma. The univariable analysis revealed that the effect of age, primary diagnosis, localization, follow-up time, and presence and number of distant organ metastasis variables on AER were found to be statistically significant (p = 0.018, p = 0.035, p = 0.002, p = 0.007, p = 0.031, p = 0.040, respectively). In patients who undergo a proximal femoral or a total femoral resection due to a musculoskeletal tumor, bipolar hemiarthroplasty is an adequate type of hip articulation method, since it does not affect the revision requirements and functional outcomes of patients with acetabular erosion.

Femoro-patellar overstuffing in total knee replacement: assessment of functional implications

Introduction:Patellofemoral overstuffing is the situation in which the antero-posterior size of the patella and / or femur is increased after total knee arthroplasty. There is a debate in the literature as to whether or not patellofemoral joint overstuffing has a clinically significant effect on post-operative outcomes.Objectives:Our goal was to determine the influence of femoro-patellar overstuffing on the functional outcome of total knee arthroplasty.Methods:It was a retrospective study of 50 total knee arthtroplasty without Patellar resurfacing, with a minimum follow-up of 12 months. We retrospectively collected epidemiological, clinical, therapeutic and evolutionary data. We performed our measurements on standard knee X-ray preoperatively and postoperatively according to the Beldman method. We calculated trochlear overstuffing, condylar overstuffing and distal femoral overstuffing which is primary endpoint. We have considered significant femoropatellar overstuffing when it is more than 15%. We evaluated the functional repercussions of femoro-patellar overstuffing at follow-up, on pain, mobility and the Western Ontario and McMaster Universities osteoarthritis index functional score (WOMAC).Results:This study shows that an increase in anterior femoral offset, posterior condylar offset and distal femroal diameter are associated with worse patient reported pain and function after total knee arthroplasty. Both Condylar and distal femoral overstuffing were statistically significant with all scores (P<0.05).Conclusion:we found that the overstuffed knees after total knee arthoplasty were more painful, stiffer and with lower physical function. Surgeon could take more care during the anterior and posterior femoral resection in order that the offset is not increased following implant insertion.

Additional distal femoral resection increases mid-flexion coronal laxity in posterior-stabilized total knee arthroplasty with flexion contracture : a computational study.

Surgeons commonly resect additional distal femur during primary total knee arthroplasty (TKA) to correct a flexion contracture, which leads to femoral joint line elevation. There is a paucity of data describing the effect of joint line elevation on mid-flexion stability and knee kinematics. Thus, the goal of this study was to quantify the effect of joint line elevation on mid-flexion laxity. Six computational knee models with cadaver-specific capsular and collateral ligament properties were implanted with a posterior-stabilized (PS) TKA. A 10° flexion contracture was created in each model to simulate a capsular contracture. Distal femoral resections of + 2 mm and + 4 mm were then simulated for each knee. The knee models were then extended under a standard moment. Subsequently, varus and valgus moments of 10 Nm were applied as the knee was flexed from 0° to 90° at baseline and repeated after each of the two distal resections. Coronal laxity (the sum of varus and valgus angulation with respective maximum moments) was measured throughout flexion. With + 2 mm resection at 30° and 45° of flexion, mean coronal laxity increased by a mean of 3.1° (SD 0.18°) (p < 0.001) and 2.7° (SD 0.30°) (p < 0.001), respectively. With + 4 mm resection at 30° and 45° of flexion, mean coronal laxity increased by 6.5° (SD 0.56°) (p < 0.001) and 5.5° (SD 0.72°) (p < 0.001), respectively. Maximum increased coronal laxity for a + 4 mm resection occurred at a mean 15.7° (11° to 33°) of flexion with a mean increase of 7.8° (SD 0.2°) from baseline. With joint line elevation in primary PS TKA, coronal laxity peaks early (about 16°) with a maximum laxity of 8°. Surgeons should restore the joint line if possible; however, if joint line elevation is necessary, we recommend assessment of coronal laxity at 15° to 30° of knee flexion to assess for mid-flexion instability. Further in vivo studies are warranted to understand if this mid-flexion coronal laxity has negative clinical implications. Cite this article: Bone Joint J2021;103-B(6 Supple A):87-93.