Functional outcome after isolated acetabular fractures.

OBJECTIVE: To evaluate objectively the effectiveness of current surgical management of displaced acetabular fractures. To provide insight into how these evaluation methods can be used to identify areas in which improvements in surgery and rehabilitation can be pursued to improve patient outcomes.

DESIGN: Consecutive case series.

SETTING: University medical center.

PATIENTS: Fifteen patients were studied, each with an isolated, displaced acetabular fracture treated with a Kocher-Langenbeck approach.

MAIN OUTCOME MEASURES: Primary outcome measures included hip muscle strength, including work (Joules/minute) and maximum torque (30 degrees/second) for abductors/adductors and flexors/extensors. Gait analysis of patients and able-bodied cohorts, including stride length, speed, and cadence, were also assessed. Motion analysis during gait was also studied for each body segment, including the trunk, pelvis, hip, knee, and ankle, in the sagittal, frontal, and axial planes. Motion data for the affected side was compared with motion data for the unaffected side, and linear gait findings for the study patients were compared to able-bodied cohorts. An assessment of clinical outcome was performed by completion of a validated Musculoskeletal Function Assessment (MFA) questionnaire and the were results correlated with muscle strength and gait analysis. Secondary outcome measures included adequacy of fracture reduction, radiographic grade, the presence and severity of heterotopic ossification at the time of the most recent follow-up, and passive range of motion of the affected and unaffected hips.

RESULTS: No statistical differences in muscle strength for each of the major muscle groups were found when the affected limb was compared with the unaffected limb. No statistical differences were found between the study patients and the able-bodied cohorts with regards to stride length, gait speed, and cadence. The only significant difference found in body segment position was trunk inclination. When the study patients were compared with able-bodied cohorts, the patients tended to walk with greater forward inclination of their trunks; this was true for all phases of gait. Total MFA scores averaged 22 (range, 0-57). Patients could be separated into two separate groups based on their total MFA score. One group (n = 6) had an average MFA score of 7 (range, 0-10), while a second group (n = 9) had an average MFA score of 32 (range, 12-57). The scores of study patients as a whole, and those of each individual group of patients, were compared with known MFA scores for nonpatients and patients in the Orthopaedic Trauma Association/Association for the Study of Internal Fixation (OTA/AO) injury group (hip and thigh). When the muscle strengths of these two groups of patients were compared, all hip flexion and extension variables were significantly weaker in the group with an average MFA score of 32, whereas none of the gait variables were different between the two groups. At an average follow-up of 24 months, seven patients had an excellent radiographic grade, four patients had a good grade, two patients had a fair grade, and two patients had a poor grade. These radiographic grades were in contrast to achieving an anatomic reduction in eleven patients, a satisfactory reduction in three patients, and an unsatisfactory reduction in one patient. Heterotopic ossification was found in eight patients, four patients had Grade 1, and four patients, had Grade 2. No statistically significant differences were observed when each MFA group was compared with each of these radiographic variables. Passive hip range of motion was not statistically different when the affected hip was compared with the unaffected hip.

CONCLUSIONS: Standardized muscle strength determination, gait, and motion analysis, and completion of an MFA questionnaire provided a thorough and revealing evaluation of patients who have undergone open reduction and internal fixation (ORIF) of a displaced acetabular fracture. Minimal alterations in body posture and affected limb motion were present in patients displaying relatively normal gait parameters, including stride length, speed, and cadence. Despite dissection of the hip musculature during surgery, normal muscle strength recovery was possible after operative repair of these acetabular fractures. However, functional outcome, as determined by MFA scores, was considerably poorer in those patients with significantly weaker hip flexion and extension strength, compared with those of patients with more desirable MFA scores. Based on the current data, it appears that the use of these and similar evaluation instruments can allow determination of factors that negatively affect outcome (hip flexion and extension strength), which otherwise may remain unknown. It is possible that identification and treatment of these factors will improve the quality of life for patients after this type of injury.