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BACKGROUND: The concept of dual mobility of total hip arthroplasties (THA) is a revolution in the prevention of dislocations and in the treatment of instability. Its use remains controversial in patients under 60 years old, providing poorer results with first generation cups coated with alumina. This study, carried out on modern dual mobility (DM) cups with a porous bilayer coating, in active patients under 60 years of age aimed to evaluate: (1) the mechanical survival of two latest generation DM THA, with failure defined as revision of acetabular or femoral implants for mechanical loosening, by comparing a tripod cup to a full pressfit cup, (2) to evaluate the complications, (3) to compare the rate of radiographic peri-prosthetic osteolysis between the 2 implants. HYPOTHESIS: The hypothesis was that the medium-term survival of modern DM cups placed in young patients was the same regardless of the type of acetabular fixation used. MATERIALS AND METHODS: This was a retrospective study of 119 latest generation DM THA with standard polyethylene, composed of 66 full pressfit cups and 53 tripod fixation cups, used in primary arthroplasty in 111 patients between 2005 and 2016. The survival study was carried out using medical records. The clinical evaluation was carried out using the modified Harris Hip Score (mHHS) as well as the self-administered Hip and Osteoarthritis Outcome Score (HOOS) and Oxford-12 questionnaires. Radiological analysis was carried out on radiographs looking for bone demineralization and acetabular and femoral lines. RESULTS: At 8.6 years (5-16), no revision for mechanical loosening was observed regardless of the type of cup. The prosthesis dislocation rate (large joint) was 1.7%: 1 case in each group (p = 1), including one revision required in the full pressfit group. Three revisions for mechanical complications were recorded: a recurrent dislocating hip on a full pressfit cup that was not sufficiently anteverted, an acetabular peri-prosthetic fracture on a full pressfit cup and a case of iliopsoas impingement with a retroverted tripod cup. The survival rate for all-cause revision was 93.8% for pressfit (95% CI: 88.2%-99.9%) vs. 96.2% for tripod (95% CI: 91.1%-100%) (p = 0.63) and for revision due to any cause excluding infection, 96.9% for pressfit (95% CI: 92.8%-100%) vs. 98.1% for tripod (95% CI: 94.4%-100%) (p = 0.7). The rate of periacetabular osteolysis was 11%, significantly more present amongst tripod cups (24%, 9 cases) compared to full pressfit cups (2%, 1 case) (p < 0.01). CONCLUSION: This series demonstrates good performance of 3rd generation DM cups with porous bilayer coating in patients under 60 years of age regardless of the type of acetabular fixation, at 8.6 years of follow-up. The rate of osteolysis around full pressfit cups remains very low, unlike that of tripod cups. The use of Double Mobility prostheses for primary hip osteoarthritis is possible in young patients, preferably with full pressfit cups (i.e., without any pegs or additional screws that may promote diffusion of polyethylene debris and osteolysis). LEVEL OF EVIDENCE: III; comparative retrospective study.
RESUMO
INTRODUCTION: Femoral megaprostheses are used for bone reconstruction surgery in patients with local tumors or who require multiple revisions. Patient reported outcome measures (PROMs) provide a subjective result and, like patient satisfaction, have become an integral part of the outcomes in orthopedics. However, the threshold of satisfaction (PASS: Patient Acceptable Symptom State) has not yet been defined in a French population after this type of arthroplasty. This led us to carry out a retrospective study on a population of patients who received a femoral reconstruction megaprosthesis in order to 1) define the PASS for the Harris Hip Score (HHS), Knee Society Score (KSS) and the Musculoskeletal Tumor Society score (MSTS), 2) study the complications. HYPOTHESIS: The PASS threshold for proximal femur and distal femur reconstruction prothesis for the HHS and the KSS, respectively, will be lower than the threshold for these same scores for primary arthroplasty. MATERIALS AND METHODS: Forty-four patients who were operated on between 2009 and 2020 were included: 23 received a proximal femur prosthesis and 21 received a distal femur prosthesis. The PASS threshold was defined using an anchoring strategy by analyzing ROC curves for the HSS for the proximal femur, KSS for the distal femur and the MSTS for all the prostheses. Complications were classified according to Henderson. RESULTS: The mean follow-up was 4.5 ± 3.6 (1-12.5) years. The PASS threshold was 47.5 (area under curve (AUC) 0.71 (0.45-0.97)) for the HHS, 69.5 (AUC 0.97 (0.92-1.0)) for the KSS knee and 62.5 (AUC 0.81 (0.61-0.99)) for the KSS function. Thirteen patients (29%) had complications, nine of whom required another surgery (20%). The most frequent were Henderson type 1 (soft tissue lesions, n = 5/44 [11%]) and type 2 (loosening, n = 5/44 [11%]) There was no relationship between satisfaction and postoperative complications (p = 0.071). DISCUSSION: Most of the patients who undergo femoral resection and reconstruction (59%) are satisfied with their function, albeit reduced, despite a high complication rate (29%). Our hypothesis is confirmed for the PASS threshold for the HHS (47.5 versus 93) and the KSS knee and function (69.5 and 62.5 versus 85.5 and 72.5). LEVEL OF EVIDENCE: IV; retrospective observational single-center study.
