Archetype analysis of the spine-hip relationship identifies distinct spinopelvic profiles.

INTRODUCTION: The position of the pelvis in the sagittal plane can vary considerably between different functional positions. Adapting the position of the acetabular cup in relation to the alignment between the spine and the hip of each individual, prior to prosthesis placement, can prevent the risk of prosthetic impingement. Taken individually, risk factors for unfavorable spinopelvic kinematics can be difficult to interpret when trying to precisely predict which patients are at risk. Furthermore, the use of classifications or algorithms can be complex, most often associated with limited values and often difficult to apply in current practices of risk assessment. HYPOTHESIS: We hypothesized that the deconstruction of the data matrix including age and spinopelvic parameters (SPT, LL, PI, LF and PI-LL) correlated with the analysis of spinopelvic kinematics could be used to define an individualized hip-spine relationship. MATERIAL AND METHOD: We applied archetypal analysis, which is a probabilistic, data-driven and unsupervised approach, to a complete phenotype cohort of 330 patients before total hip arthroplasty to define the spinopelvic profile of each individual using the spinopelvic parameters without threshold value. For each archetype, we analyzed the spinopelvic kinematics, not implemented in the creation of the archetypes. RESULTS: An unsupervised learning method revealed seven archetypes with distinct spinopelvic kinematic profiles ranging from -8.9 ° to 13.15 ° (p = 0.0001) from standing to sitting and -5. 35 ° to -10.81 ° (p = 0.0001) from supine to standing. Archetype 1 represents the "ideal" patient (A1); young patients without spinopelvic anomaly and the least at risk of mobility anomaly. Followed by 3 archetypes without sagittal imbalance according to their lumbar lordosis and pelvic incidence, from the highest to the lowest (archetypes 2-4), archetype 4 exposing a greater risk of spinopelvic kinematic anomaly compared to others. Then 2 archetypes with sagittal imbalance: archetype 5, with an immobile pelvis in the horizontal plane from standing to sitting position in anterior tilt and archetype A6, with significant posterior pelvic tilt standing, likely compensating for the imbalance and associated with the greatest anomaly of spinopelvic kinematics. Finally, archetype 7 with the stiffest lumbar spine without sagittal imbalance and significant unfavorable kinematics from standing to sitting. CONCLUSION: An archetypal approach to patients before hip replacement can refine diagnostic and prognostic features associated with the hip-spine relationship and reduced heterogeneity, thereby improving spinopelvic characterization. This risk stratification of spinopelvic kinematic abnormalities could make it possible to target patients who require adapted positioning or types of implants before prosthetic surgery. LEVEL OF EVIDENCE: IV retrospective study.

Validation of mediCAD® software for fully digital preoperative planning of total hip arthroplasty: a retrospective study.

INTRODUCTION: The planning step that precedes a total hip arthroplasty (THA) procedure is crucial. Digital planning software programs are being increasingly used, although few studies have reported on the reliability of such tools. Furthermore, no studies have been conducted on the mediCAD® software, despite it being widely used in France. This led us to conduct a retrospective study to: (1) assess the accuracy of this planning software, (2) determine the intra- and inter-rater reliability, (3) determine how obesity affects the accuracy of planning. HYPOTHESIS: THA planning is accurate and reliable when using the mediCAD® software. PATIENTS AND METHODS: This was a single center, retrospective study. One hundred one consecutive cases performed by a single experienced surgeon were planned retrospectively by two blinded surgeons on two separate occasions. The acetabular cup was cemented in 90 hips (89%), cementless in 11 hips (11%). A dual mobility cup was used in 21 hips (21%). The femoral stem was cemented in 60 hips (59%). The endpoint was the number of exact plans, defined as the same size as the actual implants. An acceptable match was defined as a difference of one size. The match was unacceptable if the planned and implanted size differed by more than 2 for the acetabular cup or by more than 1 size for the femoral stem. The intra-rater and inter-rater reliability were calculated using the intraclass correlation coefficient (ICC) with 95% confidence intervals (CI). RESULTS: Exact agreement was found by the first rater for 15 planned acetabular cups (15%) and for 45 planned femoral stems (45%) relative to the implants used. The second rater reached exact agreement for 20 planned acetabular cups (20%) and 50 planned femoral stems (50%). The intra-rater reliability for the acetabular cup was average (ICC = 0.57; 95%CI [0.43-0.69]) and poor (ICC = 0.38 95%CI [0.20-054]) for the 1st and 2nd rater, respectively. The intra-rater reliability for the femoral stem was poor for the 1st rater (ICC = 0.47 95%CI [0.30-0.61]) and the 2nd rater (ICC = 0.45 95%CI [0.29-0.60]). The interobserver reliability was low for the planned acetabular cup (ICC = 0.39 95%CI [0.21-0.54]) and the planned femoral stem (ICC = 0.42 95%CI [0.24-0.57]). Overall, when combining the two raters, exact prediction of the acetabular cup was achieved in 31 hips (19%) in non-obese patients and in 7 hips (21%) in obese patients (p = 0.62). DISCUSSION: This study found acceptable reliability of the mediCAD® software. Experience level, radiograph magnification affected the planning outcome in this study, but obesity did not. We currently do not have the ability to incorporate a reliable radiological scale for two-dimensional templating. Some surgeons prefer using a CT scan, but this costs more than conventional radiographs and exposes the patient to more radiation. This study shows that the mediCAD® software can provide satisfactory output for the preoperative planning of THA. LEVEL OF EVIDENCE: III; retrospective, diagnostic, comparative study.

Restoration of hip anatomy using computer modelling prior to total hip arthroplasty and its potential consequences in terms of lower limb-length difference.

BACKGROUND: Restoring hip anatomy during total hip arthroplasty (THA) is the gold standard. The general goal is for hips to be symmetrical in terms of height. This study aimed to analyse the effect of simulating hip length (HL) equalisation on leg-length difference (LLD) before and after THA with a computerised plan. METHODS: 141 consecutive patients were enrolled following THA. Outcomes of interest were preoperative hip-length difference (HLD) and LLD as determined on CT and final LLD as determined by simulating HL equalisation. We divided patients into 3 groups: no LLD, LLD >5 mm and LLD ⩾10 mm. RESULTS: The rate of preoperative LLD >5 mm and LLD ⩾10 mm was 37.5% and 14.8%, respectively. HL equalisation did not change LLD distribution in the overall cohort. Among patients with smaller preoperative HLs and LLDs, HL equalisation changed the rate of LLD >5 mm from 100% (n = 24) to 41.7% (n = 10) (p < 0.0001) and of LLD ⩾10 mm from 100% (n = 12) to 16.7% (n = 2) (p < 0.0001). Among patients with no preoperative LLD, HL equalisation changed the rate of LLD ⩽5 mm from 100% (n = 64) to 59.3% (n = 38) (p < 0.0001) and of LLD<10 mm from 100% (n = 76) to 89.5% (n = 68) (p = 0.006). CONCLUSIONS: Restoring biomechanical hip anatomy by HL equalisation may not be the correct goal for all patients. In patients with no LLD and shorter HLs, equalisation could result in LLD >5 mm in 40% of patients and LLD >10 mm in 10%, demonstrating the necessity to further analyse individuals and propose a personalised stem position.

Low pelvic incidence with low lordosis and distal apex of lumbar lordosis associated with higher rates of abnormal spinopelvic mobility in patients undergoing THA.

Aims: The risk factors for abnormal spinopelvic mobility (SPM), defined as an anterior rotation of the spinopelvic tilt (∆SPT) ≥ 20° in a flexed-seated position, have been described. The implication of pelvic incidence (PI) is unclear, and the concept of lumbar lordosis (LL) based on anatomical limits may be erroneous. The distribution of LL, including a unusual shape in patients with a high lordosis, a low pelvic incidence, and an anteverted pelvis seems more relevant. Methods: The clinical data of 311 consecutive patients who underwent total hip arthroplasty was retrospectively analyzed. We analyzed the different types of lumbar shapes that can present in patients to identify their potential associations with abnormal pelvic mobility, and we analyzed the potential risk factors associated with a ∆SPT ≥ 20° in the overall population. Results: ΔSPT ≥ 20° rates were 28.3%, 11.8%, and 14.3% for patients whose spine shape was low PI/low lordosis (group 1), low PI anteverted (group 2), and high PI/high lordosis (group 3), respectively (p = 0.034). There was no association between ΔSPT ≥ 20° and PI ≤ 41° (odds ratio (OR) 2.01 (95% confidence interval (CI)0.88 to 4.62), p = 0.136). In the multivariate analysis, the following independent predictors of ΔSPT ≥ 20° were identified: SPT ≤ -10° (OR 3.49 (95% CI 1.59 to 7.66), p = 0.002), IP-LL ≥ 20 (OR 4.38 (95% CI 1.16 to 16.48), p = 0.029), and group 1 (OR 2.47 (95% CI 1.19; to 5.09), p = 0.0148). Conclusion: If the PI value alone is not indicative of SPM, patients with a low PI, low lordosis and a lumbar apex at L4-L5 or below will have higher rates of abnormal SPM than patients with a low PI anteverted and high lordosis.

Risk Factors Associated With Femorotomy or Fracture During Cementless Stem Removal and Generation of an Individual Predictive Risk Score.

BACKGROUND: Femorotomy is a commonly used technique during cementless stem removal but should be preferred in selective revision cases to prevent intraoperative femoral fracture associated with deteriorated clinical outcome. Our aim was to assess the risk factors for fracture or femorotomy and develop a predictive risk stratification score. METHODS: A monocentric retrospective cohort including 202 patients was analyzed. Thirty six candidate prognostic factors were assessed. RESULTS: The following independent predictors of fracture or femorotomy were identified: presence of a "bracket sign" (Odds Ratio [OR]: 10.857; 95% Confidence interval [CI]: 2.613-45.115; P = .001) defined as a distal spot weld between the surface of the implant and closest endosteum, bone contact in zone 2 (OR: 4.700; 95% CI: 1.827-12.089; P = .001), 6 (OR: 4.966; 95% CI: 1.823-13.530; P = .002), 12 (OR: 9.660; 95% CI: 3.715-25.116; P < .0001), 13 (OR: 2.958; 95% CI: 1.009-8.021; P = .033), and global hypertrophy (OR: 0.170; 95% CI: 0.036-0.806; P = .026). The prognostic score, named Femorotomy INcidence Numeric scoring system, had good performance and discriminability; the area under the curve of the model was 0.924 (95% CI: 0.878-0.969). CONCLUSION: The only independent risk factors were those assessed on X-ray (eg, bracket sign, bone contact in zones 2, 6, 12, and 13), while global hypertrophy was protective. We noticed the importance of differentiating pedestals and "bracket signs"; the latter is an indicator of fixation of the stem. We developed a risk prediction score (Femorotomy INcidence Numeric score) of fracture or femorotomy that can be used as a companion tool to assess the risk for doing an early osteotomy of the femur.

Does delayed weight bearing in the surgical management of fractures of the upper end of the femur in the elderly lead to more complications? A prospective study.

INTRODUCTION: Fractures of the upper end of the femur (FUEF) lead to increased mortality and dependence in the elderly. However, mechanical complications after surgery persist in up to 20% of cases, which may justify a delayed resumption of full weight bearing to protect the osteosynthesis during consolidation. HYPOTHESIS: Our hypothesis was that the late resumption of weight bearing in an elderly population after a FUEF would be limited by a higher frequency of medical complications. METHODS: This was a prospective monocentric study including patients aged 80 or over with an isolated FUEF requiring osteosynthesis. The operator decided on the discharge. The primary endpoint was to show a difference in a medical complication score created for this study (APRETAR), between a group with, and a group without, weight bearing delayed by 45 days. RESULTS: Between 2016 and 2019, 254 patients (88±5.6 years, 77.6% women) were included, and of these, 70 (27.6%) had delayed weight bearing. The mean APRETAR at 45 days was greater in the delayed weight bearing group (5.9±8.6 vs. 5.7±11.0; p<0.001). One-year mortality was 12.6% (32 patients), with no difference between the two groups (p=0.51). The level of dependence was significant (IADL at 2.2±1.7), with some comorbidities (Charlson at 2.9±2.2 and CIRS-G at 6.5±4.3) and all comparable across the two groups but with low cognitive levels, especially in the group with delayed weight bearing (MMSE 15.9±10.7 vs. 21±6.9; p<0.001). CONCLUSION: This prospective study shows that delaying weight bearing in the elderly population, even for mechanical problems with FUEF, statistically increases medical complications but in a clinically acceptable manner. LEVEL OF EVIDENCE: II, Prospective cohort study.

Is the osteosynthesis of lateral malleolar fractures by pin/cerclage effective? A retrospective study.

INTRODUCTION: Lateral malleolar fractures are present in about 90% of ankle fractures. The standard treatment is plate osteosynthesis. Although the plates are thin, the risk of cicatricial complications is not insignificant and can lead to cutaneous or even infectious complications and the latter can cause functional repercussions. We therefore aimed to evaluate a technique consisting of osteosynthesis of the lateral malleolus using two cerclages and two intramedullary pins. HYPOTHESIS: Our hypothesis is that the use of osteosynthesis by pin/cerclage of the lateral malleolus makes it possible to have objective reduction criteria, similar to the reference treatment. METHODS: This is a retrospective study of patients who had an interligamentous spiral fracture of the lateral malleolus. One group of patients had internal fixation of the lateral malleolus fracture by pins, and the other by plate. Our primary outcome was to compare the reduction of the fracture of the lateral malleolus between the two techniques using the "Dime sign", the measurement of the talocrural angle and respect for Shenton's line. RESULTS: A total of 118 lateral malleolar fractures were included: 56 patients (47.5%) in the "pin" group and 62 patients (52.5%) in the "plate" group. The mean age of the patients was 46.6 years (17.4) with an average body mass index of 25.2kg/m2 (4.8) and 55.1% of the patients were women. We found a difference in the reduction criteria between the two groups by looking at Shenton's line: 73.2% (41/56) of postoperative X-rays in the "pin" group respected Shenton's line, compared to 90.3% (56/62) in the "plate" group (p=0.02). We did not find any difference regarding the "Dime sign" and the talocrural angle. CONCLUSION: Our study shows the superiority of plate osteosynthesis for lateral malleolar fractures compared to pin/cerclage osteosynthesis, regarding one of the three radiological criteria for reduction. No significant difference was found in the one-year rates of complications and of hardware removal, between the two groups. LEVEL OF EVIDENCE: IV, retrospective study.

Proximal femur versus acetabular extra-articular resection of the hip joint for primary malignant bone tumors: a retrospective comparative review of 33 cases.

INTRODUCTION: Extra-articular resection (EAR) of the hip joint is prone to significant complications and morbidity. Thus, this study evaluates the cumulative incidences and main reasons of reoperation following EAR of primary malignant bone tumors (PMBT) of the hip to determine whether the outcomes are different between EAR of the pelvis and that of the proximal femur. PATIENTS AND METHODS: Thirty-three patients presented with a PMBT of the proximal femur or pelvis were included in this study. Among all PMBTs, 58% originated from the pelvis and 42% were from the proximal femur. Twenty patients had chondrosarcomas (61%), 10 had osteosarcomas (30%), and 3 had sarcomas of another histological subtype (9%). RESULTS: The mean follow-up was of 76 months (range: 24-220 months). The cumulative probabilities of revision for any reason were 52% (95% confidence interval [CI] 30-70%) 5 years after surgery. The 5-year cumulative probabilities of revision were 13% (95% CI 4-27%), 24% (95% CI 10-42%), and 34% (95% CI 14-56%) for mechanical, infectious, and tumoral reasons, respectively. The 5-year cumulative probabilities of revision for any reason were 78% (95% CI 37-94%) and 14% (95% CI 2-38%) for the pelvis and proximal femur, respectively (p = 0.004). Posterior column preservation was significantly associated with more mechanical complications even after adjusting for the resection site (p = 0.043). CONCLUSION: Half of patients undergoing EAR of the hip joint for PMBT of the proximal femur or acetabulum will require another operation. EAR of the pelvis is associated with significantly worse outcome than EAR of the proximal femur.

Ankle CT scan allows better management of posterior malleolus fractures than X-rays.

PURPOSE: Undiagnosed and undertreated posterior malleolus fractures lead to early ankle instability and arthritis. A preoperative CT scan could improve the management of those fractures. This study assessed the benefits of a systematic ankle CT scanner to diagnose and manage posterior malleolus fracture. METHODS: A monocentric retrospective cohort study was conducted. Sixty consecutive patients with bimalleolar fractures were operated and underwent a preoperative CT scan. The mean age was 50.0 years old (18.6 years old) with a mean body mass index of 20.3 (kg/m2) (11.4 kg/m2) and 71.7% (43/60) of women. The primary outcome was the rate of posterior malleolus fragment diagnosed on X-rays and on CT scan. Secondly, interobserver and interobserver's agreement were compared between conventional X-rays and CT scan. RESULTS: Thirty-five (58.3%) posterior fragment fractures were observed on X-rays and 53 (88.3%) on the preoperative CT scan (p < 0.01). The intraobserver reproducibility for X-rays was low (0.02 [- 0.23; 0.27]) and moderate for CT scan (0.45 [0.0; 0.84]). The interobserver reproducibility for X-rays was moderate (0.39 [0.15; 0.60]) and excellent for CT scan (0.78 [0.0; 1.0]). CONCLUSION: A wide proportion of bimalleolar fractures are associated with posterior malleolus fractures and undiagnosed with standard X-rays. We advocate a systematic preoperative CT scan in the management of bimalleolar fractures. LEVEL OF EVIDENCE: Level IV, retrospective cohort study. TRIAL REGISTRATION NUMBER: 2218999v0, date of registration: 11/08/2020 (retrospectively registered).

Pelvic position, lying on a traction table, during THA by direct anterior approach. Comparison with the standing position and influence on the acetabular cup anteversion.

INTRODUCTION: The placement of prostheses for a total hip arthroplasty (THA) is essential to limit complications and optimize functional results. In a recent study of more than 100 THA placed through a direct anterior approach using a traction table, we found that the mean anteversion of the cup was greater (30°) than recommended (20°). To explain this phenomenon, we considered that the anterior pelvic plane (APP), defined by the plane passing through the anterior-superior iliac spines and the pubic symphysis, which serves as a landmark for the placement and calculation of the anteversion of the cup, was not horizontal when the patient was lying on the traction table. This concept has not been evaluated so we conducted a prospective study to: 1) measure the position of the pelvis on a traction table; 2) compare to the standing position, 3) assess its impact on the anteversion of the cup. HYPOTHESIS: The standing pelvic version is identical to the supine pelvic version on the traction table. MATERIAL AND METHODS: A prospective 3-month monocentric study was conducted. All patients operated on for a THA by a direct anterior approach, on a traction table, were included. The position of the pelvis was assessed by measuring the tilt of the APP on lateral pelvic X-rays, while on the traction table and while standing. The impact of the position of the pelvis on the positioning of the cup, as well as the anteversion, were measured using the EOS imaging system. The anatomic anteversion of the cup was measured in relation to the APP. RESULTS: Fifty-eight patients were included (32 women, 26 men) with an average age of 67 years. The tilt of the supine APP was 6°±8.3 [range of -10.5 to 31.0] (indicating a retroverted pelvis on the traction table). The difference between the tilt of the standing and lying APP (within 90°) was not significant (standing was on average 4.5° [range of -11.0 to 27.0] versus lying on the table, was on average 6° [range of -10.5 to 31.0] (p=0.75). A strong correlation was observed between the tilt of the supine APP and the anatomic anteversion of the cup (p<0.001). Thus, the more retroverted the pelvis was on the traction table, the lower the anatomic anteversion of the acetabular cup. CONCLUSION: The supine pelvis on the traction table is not always horizontal and its position on the traction table is similar to its standing position, within 90 degrees. The analysis of the positioning of the preoperative pelvis appears to be essential in the planning of a THA through direct anterior approach using a traction table. LEVEL OF EVIDENCE: IV; Prospective Cohort Study.

Were protective procedures against SARS-CoV-2 effective in an orthopaedic and trauma centre during the lockdown period? A retrospective study.

PURPOSE: The SARS-CoV-2 epidemic started in December 2019 in Wuhan. The lockdown was declared on March 16, 2020 in France. Our centre had to adapt daily practices to continue to take care of bone and soft tissue tumours and emergencies. Through this study, we wanted to assess the various procedures implemented during the lockdown period between March 17 and May 10. METHODS: A monocentric retrospective cohort study was conducted in Cochin Hospital (Paris, France). Patients included were those who had surgery during the lockdown period. To take care of COVID-19 positive and negative patients, various procedures have been set up: reverse transcriptase polymerase chain reaction (RT-PCR) tests for all hospitalized patients, a specific unit for COVID-positive patients, a specific surgical room, and use of protective personal equipment. To allow the effectiveness of the procedures implemented, we evaluated the number of complications attributed to SARS-CoV-2 and the number of patients who became COVID positive during hospitalization. RESULTS: During the lockdown period, there were 199 procedures of three types of procedures in our centre: 79 traumatology procedures (39.7%), 76 of bone and soft tissues tumours (38.2%), and 44 procedures related to infection (22.1%). We observed 13 complications (6.5%) during hospitalization, and only one patient became COVID-19 positive during the hospitalization. CONCLUSION: The COVID-19 epidemic has been a challenge for organization and adaptation to manage all COVID-19 positive and COVID negative. Through this study, we wanted to assess our procedures taken. They had been effective due to the low number of contamination and complications.

Survival and complications in hinged knee reconstruction prostheses after distal femoral or proximal tibial tumor resection: A retrospective study of 161 cases.

INTRODUCTION: Hinged knee megaprostheses are mainly used for reconstruction after tumor resection. They may incur complications, but this has not been assessed in the French literature, except in small series at short follow-up. We therefore conducted a large-scale nationwide multicenter retrospective study with a minimum 5 years' follow-up. The objectives were (1) to compare survival between distal femoral and proximal tibial reconstruction prostheses, and (2) to analyze complications and failure. HYPOTHESIS: Distal femoral hinged reconstruction prostheses show longer survival with fewer complications than proximal tibial prostheses. MATERIAL AND METHODS: One hundred sixty-one patients were included: 118 in the distal femoral group, and 43 in the proximal tibial group. Tumors were mostly osteosarcomas (90 cases) or chondrosarcomas (31 cases). Mean age was 37 years (range, 12-86 years). Complications were assessed on the Henderson classification. Failure was defined by prosthesis anchor exchange or amputation. RESULTS: At a mean 9 years' follow-up (range, 5-23 years), implant survival was longer in the distal femoral group: 5- and 10-year survival, 84% [95% CI, 75-89] and 70% [95% CI, 59-79] versus 74% [95% CI, 69-85] and 43% [95% CI, 23-61] (p=0.02). Revision surgery for complications mainly concerned aseptic loosening (19%, 30 cases) or deep infection (16%, 25 cases) and more often involved the proximal tibia (65% vs. 43%, 28 vs. 51 cases; OR 2.4 [95% CI, 1.2-5.1]; p=0.02). DISCUSSION: Hinged knee reconstruction prosthesis is a solution in tumoral pathology, but with a high risk of complications (loosening and infection) and a higher failure rate in the proximal tibial reconstruction prosthesis. LEVEL OF EVIDENCE: IV, case series.

Dual mobility constructs in revision total hip arthroplasty: survivorship analysis in recurrent dislocation versus other indications at three to twelve-year follow-up.

BACKGROUND: The aim of this retrospective study was to evaluate the clinical, radiologic, and survival results of dual mobility (DM) sockets in revision total hip arthroplasty (THA) performed for instability versus revision THAs performed for other reasons. METHODS: From a computerized database, we identified 84 revision THAs using a modern DM socket performed in 81 patients with a mean age of 71 years. Indication for revision was recurrent dislocation in 47 hips, and other reasons in the remaining 37 hips. A survivorship analysis according to the actuarial method was carried out on the entire series using revision for any cause, revision for dislocation, and radiological cup loosening revised or not, as the end points. RESULTS: Of the 81 patients, twelve died, six were lost to follow-up, eight had been revised, and 55 patients (58 hips) were unrevised and alive at a mean follow-up of 6.4 years. Dislocation occurred in four of the 47 (8.5%) hips for which indication for revision was dislocation versus one of the remaining 37 (2.7%) hips [odds ratio = 3.4 (0.4-31.3), p = 0.07]. According to our criteria, three acetabular components of which one was revised were considered as loosened. When using revision for dislocation as the end-point, the survival rate at seven years was 90.4 ± 5.3% (IC95%, 79.9-100) in the 47 hips for which the indication for revision was dislocation versus 100% in the remaining 37 hips (log-rank, p = 0.5). CONCLUSIONS: The current study indicated that DM sockets represent an interesting solution to prevent dislocation in revision THAs at mid-term follow-up.

Patients with Revision Modern Megaprostheses of the Distal Femur Have Improved Disease-Specific and Health-Related Outcomes Compared to Those with Primary Replacements.

We asked whether there would be any difference between primary and revision modern cemented fixed hinge megaprosthesis of the distal femur in function and activity-related outcomes following treatment of a bone tumor. An identical custom-made fixed hinge cemented megaprosthesis with a hydroxyapatite collar was used in all cases. The main outcomes were joint-specific function, disease-specific activity, and health-related quality of life. Implant survival was also evaluated. Patients in the revision group performed slightly better than patients in the primary group on disease-specific (Toronto Extremity Salvage Score, p = 0.033; Musculoskeletal Tumor Society, p = 0.072) and health-related outcomes (Short Form 36 [SF-36] physical component, p = 0.085; SF-36 mental component, p = 0.069) but not on joint-specific outcomes (Knee Society Score, p = 0.94). The cumulative probabilities of revision for any reason were 14.5% (7-25%) at 5 years with no statistically significant difference between primary and revision procedures (p = 0.77). In conclusion, patients undergoing a revision have similar joint-specific functional outcome but improved disease-specific and health-related outcomes. Implant survival are similar between groups.