RESUMEN
Background: In reverse shoulder arthroplasty (RSA), the ideal combination of baseplate lateralization (BL), glenosphere size (GS), and glenosphere overhang (GOH) with a commonly used 145° neck shaft angle (NSA) is unclear. This is the first study evaluating correlations of body height (BH), humeral head size (HS), glenoid height (GH), and association of gender with best glenoid configurations for range of motion (ROM) maintaining anatomic lateralization (aLAT) for optimized muscle length in 145° and less distalized 135° RSA. Methods: In this computer model study, 22 computed tomographies without joint narrowing were analyzed (11 male/female). A standardized semi-inlay 145° platform stem was combined with 20 glenoid configurations (baseplate [B] 25, 25 + 3/+6 lateralized [l], 29, 29 + 3/6l combined with glenosphere 36, 36 + 2 eccentric [e], 36 + 3l, 39, 39 + 3e, 39 + 3l , 42, 42 + 4e). Abduction-adduction, flexion-extension, external rotation-internal rotation, total ROM (TROM), and total notching relevant (TNR) ROM were computed, best TROM models respecting aLAT (-1 mm to +1 mm) and HS/GH recorded. Second, the 145° models (Ascend Flex stem; Stryker, Kalamazoo, MI, USA) were converted and compared to a 135° inlay RSA (New Perform stem; Stryker, Kalamazoo, MI, USA) maintaining GOH (6.5-7 mm) and aLAT. Results: Best 145° models had eccentric glenospheres (mean BL: 3.5 mm, GOH 8.8 mm, GS 38.1 mm, distalization 23 mm). The 135° models had concentric glenospheres, mean BL 3.8 mm, GOH 6.9 mm, GS 39.7 mm, and distalization 14.1 mm. HS showed the strongest positive correlation with BL in 145° and 135° models (0.65/0.79). Despite reduced GOH in smaller females with a 135° NSA, adduction, external rotation, extension, TNR ROM, and TROM were significantly increased (P = .02, P = .005, P = .005, P = .004, P = .003), abduction however reduced (P = .02). The same trends were seen for males. Conclusion: HS is a practical measure in surgery or preoperatively, and the strong positive correlation with BL is a useful planning aid. Despite reduction of GOH, conversion to a less distalized 135° NSAinlay design is powerful to maintain and even significantly increase all components of TNR ROM (extension/external rotation/adduction) in small females with the drawback of reduced abduction which may however be compensated by scapula motion. Lateralization with a less distalized 135° RSA optimizes muscle length, may facilitate subscapularis repair, and maintains highest rigid body motion.
RESUMEN
INTRODUCTION: Longer life expectancy is accompanied by a higher incidence of fragility fractures of the pelvis (FFP), which has repercussions on mortality and nursing home admissions. Given the paucity of data at French healthcare facilities, we carried out a retrospective study to (1) evaluate how surgical treatment of FFP with posterior displacement (type III and IV according to Rommens and Hofmann) affects a patient's pain, functional status and ability to stay at home and (2) evaluate the postoperative complications and mortality rate. HYPOTHESIS: Surgery for posteriorly displaced FFP will relieve pain and preserve the patient's independence. METHODS: All the patients over 65 years of age who were operated on for a posterior FFP between January 2015 and August 2020 were included in this prospective, single-center study. The demographics, fracture type, details of the surgical treatment, complications and mortality were analyzed. Pain (visual analog scale, VAS), functional status (Activity of Daily Living [ADL] and Instrumental Activity of Daily Living [IADL]), mobility (Parker score) and rates of nursing home admissions were compared before the fracture, after surgery and at a mean follow-up of 28 months (minimum follow-up of 1 year). RESULTS: Forty-eight patients with a mean age of 75 years were included. Twenty-four of these patients (50%) had at least two comorbidities. The FFPs were either type IV (31/48; 65%) or type III (17/48; 35%). The mean VAS for pain was significantly lower on the first day postoperative (3.5 versus 4.8; p=0.02). This significant reduction continued upon discharge from the hospital (1.95; p=0.003) and persisted at the mean follow-up of 28 months (2.2; p=0.64). The complication rate was 15% (7/48) and the mortality rate at the final review was 15% (7/48). Among the surviving patients, 81% (29/36) returned to living at home. The ADL (5.1 versus 5.8; p=0.09), IADL (5.9 versus 6.9; p=0.15) and Parker score (6.8 versus 8.2; p=0.08) at the final review were not significantly different from the values before the fracture. CONCLUSION: This is the first French study of patients operated on for an FPP. Fixation of posteriorly displaced fractures allows surviving patients to retain their mobility. Pain relief is achieved quickly and maintained during the follow-up period. Thus, our initial hypothesis is affirmed. The complication rate is not insignificant; given the complexity of this surgery, percutaneous treatment is preferable. LEVEL OF EVIDENCE: IV; retrospective study.