Is Displacement of the Lesser Trochanter Associated With Functional Outcome in Older Adults With Intertrochanteric Fractures?

Abstract

BACKGROUND Lesser trochanter displacement in intertrochanteric fractures has been linked to fracture instability and altered hip biomechanics, with evidence suggesting that proximal or medial displacement of the fragment by ≥ 10 mm may lead to poorer clinical outcomes. However, whether such displacement is associated with multidomain functional outcomes and patient performance remains unclear. QUESTIONS/PURPOSES In older adults with intertrochanteric fractures treated with internal fixation using a cephalomedullary nail, we asked: (1) Were functional outcome measures, including the Harris hip score (HHS), de Morton Mobility Index (DEMMI), and the Barthel Index, negatively associated with lesser trochanter displacement of ≥ 10 mm? (2) Was lesser trochanter displacement of ≥ 10 mm associated with a decreased ability to complete tasks during performance assessments and inferior performance scores on the Functional Reach Test (FRT), Timed Up and Go test (TUG), and 5 Times Sit-to-Stand (5TSTS) test? METHODS Between January 2021 and October 2023, four fellowship-trained orthopaedic surgeons at a Level I trauma center treated older adults with intertrochanteric hip fractures. Short cephalomedullary nails were used in approximately 90% of patients, typically for displaced fractures, including both stable and unstable types. Of the 123 patients treated with a cephalomedullary nail, 7% (9) were lost to follow-up before 1 year, 9% (11) died within 1 year, and 12% (15) were excluded based on predefined criteria, leaving 72% (88) of patients for analysis in this retrospective comparative study. There was no evidence of differential loss to follow-up or mortality between the displacement groups. Patients were divided into two groups based on postoperative lesser trochanter displacement: patients with < 10 mm of proximal or medial displacement, including an intact lesser trochanter (n = 44), and patients with displacement of ≥ 10 mm (n = 44). Baseline characteristics, including demographics, American Society of Anesthesiologists classification, and preinjury Barthel Index, did not differ between the groups. Functional outcomes, including the HHS, the DEMMI (which assesses mobility across a range of physical tasks), and the Barthel Index (which measures independence in activities of daily living) were assessed at 3 months and 1 year postoperatively. All three scores range from 0 to 100, with higher scores indicating better function. These capture different domains of recovery, allowing for a more comprehensive evaluation of patient outcomes. Performance tests (FRT, TUG, 5TSTS) were assessed at the same time points by experienced orthopaedic surgeons, and the groups were compared on those endpoints. The minimum clinically important difference (MCID) or minimal detectable change at 95% confidence (MDC95) values were: HHS (MCID = 16 to 18), DEMMI (MCID = 10), Barthel Index (MCID = 8.4), FRT (MDC95 = 6.4 to 8.2 cm), TUG (MCID = 2.9 to 4.9 seconds), and 5TSTS (MCID = 3.6 seconds). RESULTS We found no clinically important difference in HHS at either 3 months or 1 year. Patients whose fractures had < 10 mm of displacement showed higher DEMMI scores at 3 months (50 ± 15 versus 37 ± 13, mean difference 13 [95% confidence interval (CI) 7 to 19]; p < 0.001) and a borderline meaningful difference at 1 year (52 ± 17 versus 42 ± 15, mean difference 10 [95% CI 3 to 16]; p = 0.01). Barthel Index scores were also higher at 3 months (85 ± 14 versus 68 ± 20, mean difference 17 [95% CI 9 to 24]; p < 0.001) but not at 1 year. Patients with lesser trochanter displacement of < 10 mm also demonstrated better performance in the TUG test at both 3 months (48 ± 31 versus 68 ± 31 seconds, mean difference -20 [95% CI -34 to -5]; p = 0.01) and 1 year (37 ± 27 versus 52 ± 32 seconds, mean difference -15 [-29 to -1]; p = 0.03). No meaningful differences were observed in the FRT or the 5TSTS test at either time point. A higher percentage of patients with < 10 mm of displacement completed the tests (93% [41 of 44] versus 73% [32 of 44]; p < 0.001). CONCLUSION Intertrochanteric fractures with ≥ 10 mm of lesser trochanter displacement were associated with some poorer short-term functional and patient performance outcomes compared with patients with less displacement, although these differences diminished over time. The possible clinical benefit of surgically addressing the displaced fragment should be carefully weighed against the risks associated with a more extensive procedure. Further studies are warranted to address this issue. LEVEL OF EVIDENCE Level III, therapeutic study.