To provide insight into rotationplasty, we reviewed walking oxygen/energy cost and gait biomechanics, comparing it to above-knee amputation patients(AKA) (to inform clinical decision-making), and to healthy individuals (to assess deviation from normal). A literature search was conducted on September 30, 2024, using terms: rotationplasty, oxygen/energy cost of walking, and gait biomechanics. Small case reports were excluded. Methodological quality was assessed and meta-analyses (random-effects model, including heterogeneity assessment) with forest plots were performed for walking speed, cadence, stride length, and energy cost, while gait biomechanics outcomes were described qualitatively. Fifteen studies (225 rotationplasty patients) were included. Oxygen/energy cost of walking was 12.5 % lower for rotationplasty patients compared to AKA (SMD:0.57,p = 0.01), while was 34.5 % higher compared to healthy participants (SMD:2.55,p < 0.001). Gait biomechanics were like AKA, except for reduced compensatory knee power on the unaffected side in rotationplasty patients. Compared to healthy participants, rotationplasty patients had lower walking speed (18.1 %,p < 0.001), reduced cadence (6.8 %,p < 0.05), shorter stride length (9.5 %,p < 0.05), longer double support time, more lateral trunk and pelvic tilt, reduced knee flexion in loading response and swing, and a greater compensatory joint power with a 13.9 % higher vertical ground reaction force in the unaffected leg. This systematic review showed that rotationplasty is energetically preferable compared to AKA as oxygen/energy cost of walking was moderately lower compared to AKA, with reduced compensatory knee and hip power on the unaffected side. Walking energy cost was higher, and gait biomechanics more deviant in rotationplasty patients compared to healthy participants.

Rotationplasty is a surgical procedure primarily performed in patients with malignancies around the knee. Altered gait mechanics after surgery, such as reduced flexion of the (pseudo)knee and ipsilateral hip and changes in ground reaction forces, may predispose patients to osteoarthritis (OA) in the lower extremities. This study evaluated the long-term prevalence of OA and its association with pain and daily functioning. Rotationplasty survivors who underwent surgery between 1980 and 2002 in Amsterdam received radiographic assessment of the (pseudo)knee, contralateral ankle, and both hips (weight-bearing mortise, lateral and AP views). OA was graded using the Kellgren-Lawrence scale. Functional outcomes, pain, quality of life, and sports participation were evaluated with the FAOS, AOFAS, and Harris Hip Score questionnaires. Statistical analyses included t-tests, Mann-Whitney U, chi-square, and Fisher's exact tests. Thirty patients (mean age 49.4 ​± ​9.2 years; mean follow-up 32.4 ​± ​4.6 years) participated. Moderate-to-severe OA was found in 43 ​% of ipsilateral (pseudo)knees, 10 ​% of contralateral ankles, 33 ​% of ipsilateral hips, and 11 ​% of contralateral hips. Osteophytes were most common in the anterior tibial and subtalar regions (20 ​%), and joint space narrowing was most frequent in the subtalar (20 ​%) and medial tibiotalar (13 ​%) regions. Functional scores were generally favorable. The presence of osteoarthritis in the pseudo-knee was significantly associated with longer follow-up time. Functional outcomes after rotationplasty are well preserved over time, despite a higher prevalence of osteoarthritis in the (pseudo)knee compared to the contralateral ankle as a long-term consequence of the procedure.

Giant cell tumor of bone (GCTB) is a rare, locally aggressive, intermediate-grade neoplasm. While typically benign, GCTB can exhibit atypical behavior, including indolent pulmonary metastases and malignant transformation. This study characterizes malignant and metastatic GCTB, distinguishing primary malignant GCTB (PM-GCTB), secondary malignant GCTB (SM-GCTB), and secondary osteosarcoma, and evaluates their outcomes. A retrospectively review of 520 patients with suspected GCTB treated between 1985–2021 was performed, with malignant cases followed through 2025. Diagnosis was confirmed histologically and, where available, by H3F3A/H3F3B mutation testing. PM-GCTB was defined as a de novo high-grade sarcoma. SM-GCTB and secondary osteosarcoma were defined as malignant transformations of previously benign, histologically proven GCTB. Benign pulmonary metastases were analyzed separately. Outcomes were descriptively assessed. Twelve patients (2.4 %) had malignant GCTB: five PM-GCTB (1.0 %), five SM-GCTB (1.0 %), and two secondary osteosarcoma (0.4 %). Three patients (0.6 %) developed histologically benign pulmonary metastases with indolent behavior. Three SM-GCTB patients transformed within one year despite benign baseline pathology, indicating true rapid malignant progression rather than diagnostic error. Median latency to malignant transformation was 7.5 years for SM-GCTB and up to 35 years for secondary osteosarcoma. SM-GCTB showed the highest disease-specific mortality (80 %), compared to PM-GCTB (20 %) and secondary osteosarcoma (0 %). None malignant transformations occurred following denosumab or radiotherapy. Three aggressive GCTB variants were identified: benign pulmonary metastatic GCTB, PM-GCTB, and secondary malignant transformation. SM-GCTB and osteosarcoma arise from benign GCTB but differ in morphology and prognosis. Because malignant transformation is exceptionally rare and symptomatic, a patient-centered, symptom-driven follow-up strategy is preferred over routine lifelong radiologic surveillance.

The need for curettage of atypical cartilaginous tumors (ACT) is under debate. Curretage results in defects that weaken the bone potentially leading to fractures. The purpose of this study was to retrospectively determine postoperative fracture risk after curettage of chondroid tumors, including patient-specific characteristics that could influence fracture risk. A total of 297 adult patients who underwent curettage of an ACT followed by phenolisation and augmentation were retrospectively evaluated. Explanatory variables were, sex, age, tumor size, location, augmentation type, and plate fixation. The presence of a postoperative fracture was radiologically diagnosed. Included patients had at least 90 days of follow-up. A total of 183 females (62%) were included and 114 males (38%), with an overall median follow-up of 3.2 years (IQR 1.6–5.2). Mean diameter of the lesions was 4.5 (SD 2.8) cm. Patients received augmentation with allograft bone (n = 259, 87%), PMMA (n = 11, 3.7%), or did not receive augmentation (n = 27, 9.1%). Overall fracture risk was 6%. Male sex (p = 0.021) and lesion size larger than 3.8 cm (p < 0.010) were risk factors for postoperative fracture. Curettage of ACT results in an overall fracture risk of 6%, which is increased for males with larger lesions.

Background: Rotationplasty is a surgical procedure primarily used for malignant bone tumors around the knee when conventional limb salvage is not feasible because of tumor extent or patient preference. The procedure repurposes the ankle to function as a pseudo knee. While early outcomes are generally good, long-term gait performance in adulthood has not been well described. Questions/purposes: This study addresses the following questions about patient outcomes 20 years or more after rotationplasty: (1) What are the walking speed and energy cost as well as the spatiotemporal and gait parameters compared with a control group without lower limb diseases? (2) How are walking speed and energy cost related to age, follow-up duration, and gait parameters? (3) Does thigh-shank length discrepancy correlate with the energy cost of walking and gait parameters? Methods: Between 1980 and 2002, a total of 70 patients underwent rotationplasty (all Winkelmann Type A1) at two centers in Amsterdam. Of these, 37% (26) died, 4% (3) underwent amputation, and 9% (6) could not be traced. Of the remaining 35 patients, 6% (2) lived abroad, 9% (3) declined participation, and 3% (1) had a nonfitting prosthesis, leaving 83% (29 of 35) of patients available for evaluation at a median (IQR) follow-up time of 33 years (29 to 35). Rotationplasty was performed for osteosarcoma in 76% (22 of 29) of patients, Ewing sarcoma in 7% (2), other malignancies in 10% (3), hemangioma in 3% (1), and femoral deficiency in 3% (1), all by a single orthopaedic surgeon. This cohort included 52% (15 of 29) male and 48% (14 of 29) female patients. The control group, obtained from the institutional normative database, included 38 participants for analyses of the energy cost of walking and 27 participants for analyses of gait without lower limb diseases or systemic conditions affecting gait or energy cost, and was comparable with the rotationplasty group in age, sex, and BMI. Function was evaluated by walking speed, energy cost of walking, and gait parameters for spatiotemporal kinematics and kinetics and compared with the same parameters for the control group. Furthermore, outcomes were compared between patients with and without measurable thigh-shank length discrepancy. Statistical analyses included independent t-tests, statistical parametric mapping, and Pearson correlations. Results: Compared with the control group, patients after rotationplasty walked slower (mean ± SD 1.2 ± 0.2 versus 1.4 ± 0.1 m/s, mean difference -0.2 [95% confidence interval (CI) -0.3 to -0.1]; p < 0.001) with a higher energy cost (4.4 ± 0.7 versus 3.5 ± 0.4 J/kg/m, mean difference 0.9 [95% CI 0.6 to 1.2]; p < 0.001). Cadence was lower (100 ± 7 versus 108 ± 7 steps per minute, mean difference -8 [95% CI -11 to -4]; p < 0.001) and stride length shorter (1.4 ± 0.2 versus 1.5 ± 0.1 m, mean difference -0.1 [95% CI -0.2 to -0.1]; p = 0.01). The double-support phase from the contralateral leg to the rotationplasty leg was longer (at 13.1% ± 1.9% versus 11.8% ± 1.2% of the gait cycle, mean difference 1.4% [95% CI 0.5% to 2.3%]; p = 0.003). Statistically significant differences were observed at specific phases of the gait cycle: Patients with rotationplasty lacked knee flexion during loading response and midstance, whereas the intact leg showed increased ankle dorsiflexion and greater knee and hip flexion during stance, accompanied by increased ground-reaction force in loading response and push-off. Walking speed increased very strongly as cadence increased (r = 0.7 [95% CI 0.6 to 0.8]; p < 0.001) and increased moderately as stride length increased (r = 0.3 [95% CI 0.1 to 0.5]; p < 0.01). As walking speed increased, walking energy cost decreased moderately (r = -0.4 [95% CI -0.6 to -0.2]; p < 0.001). With the numbers available, no associations were found between thigh-shank length discrepancy and walking speed, energy cost, joint angles, or joint moments. Conclusion: More than two decades after rotationplasty, patients demonstrated lower walking speed and higher energy cost of walking than the control group, which is expected given the magnitude of the procedure. Compared with previous reports, the energy cost was not higher at longer follow-up and approached normal values, exceeding those typically observed after transfemoral amputation. Although the absence of knee flexion during stance was associated with compensatory strategies, mainly in the contralateral limb, overall gait performance remained functional, with preserved pseudo knee mechanics. No differences were observed between patients with and without thigh-shank length discrepancy, providing no clear guidance for surgical length-correction strategies. Despite biomechanical deviations from normal gait, long-term function after rotationplasty appears durable and energy efficient, which can help clinicians to counsel patients on realistic expectations and functional potential. Further studies comparing rotationplasty with transfemoral amputation and limb-salvage surgery are warranted to better inform shared decision-making. Level of Evidence: Level III, therapeutic study.

Primary malignant bone tumors of the foot are rare, with limited and heterogeneous data on. characteristics, management, and outcomes. This study aims to provide an overview of the epidemiology, treatment, and prognosis of these tumors through a systematic review and cohort analysis. PubMed, Embase, and Web of Science were searched for studies on osteosarcoma, Ewing’s sarcoma, and chondrosarcoma of the foot. Studies in English or German including ≥ 10 patients with original data were eligible. Demographic, clinical, treatment, and outcome data were extracted. Additionally, a retrospective review was performed of all patients with foot malignancies (chondrosarcoma, Ewing sarcoma or osteosarcoma) treated at Amsterdam UMC (2013–2024). Data were pooled for analysis. Eighteen studies met the inclusion criteria, comprising 884 patients including the single center cohort. Osteosarcoma, Ewing’s sarcoma, and chondrosarcoma were the most common malignancies, most frequently affecting the calcaneus, metatarsals, and phalanges, respectively. The median diagnostic delay was 9 (IQR 6–14) months, with pain and swelling as the predominant presenting symptoms. Below-knee amputation was the most common surgical procedure, particularly for hindfoot tumors. Local recurrence rates were highest in osteosarcoma (19%), while Ewing’s sarcoma had the highest incidence of metastatic disease (56%). Disease-specific mortality at last follow-up was 40% for osteosarcoma, 50% for Ewing’s sarcoma, and 21% for chondrosarcoma. The single-centre cohort mirrored these findings, highlighting the challenges of delayed diagnosis and inadvertent surgery. Primary malignant bone tumors of the foot present significant diagnostic and therapeutic challenges, with high rates of recurrence and metastasis. Early recognition, referral to specialized centers, and multidisciplinary management are essential to improve outcomes. Future research should focus on prospective data collection, standardized reporting, and patient-reported outcomes to guide optimal care.