Functional outcomes after operatively treated patella fractures.

OBJECTIVES:
To evaluate the midterm functional outcomes of patients with isolated operatively treated patella fractures.

DESIGN:
Prospective cohort and retrospective clinical and radiographic assessment.

SETTING:
A Level I and Level II trauma center.

PATIENTS/PARTICIPANTS:
Two hundred forty-one patients underwent operative intervention for a displaced patella fracture between 1991 and 2007. After appropriate exclusions, 110 patients met criteria. A total of 40 (36%) patients with isolated, unilateral, operatively treated patella fractures with minimum 1-year follow-up agreed to participate in this study and return for functional testing. Mean follow-up was 6.5 years (range, 1.25-17 years).

INTERVENTION:
Enrolled patients were treated with one of the following methods: standard tension band with Kirschner wires, tension band through 2 cannulated screws, longitudinal anterior banding with cerclage, or partial patellectomy.

MAIN OUTCOME MEASUREMENTS:
All enrolled patients were evaluated with the SF-36 and an injury-specific questionnaire (Knee Injury and Osteoarthritis Outcome Scores) and asked to self-report symptomatic hardware. Patients were also evaluated by physical examination assessing range of motion and Biodex bilateral quadriceps isometric and isokinetic comparisons.

RESULTS:
The mean normalized SF-36 physical composite score and the mean normalized Knee Injury and Osteoarthritis Outcome Scores subscale scores (pain, 71.7; symptoms, 66.3; activities of daily living, 75.1; sport/recreation, 45.2; quality of life, 49.6) were statistically different (P < 0.05) from reference population norms. Removal of symptomatic fixation was required in 52% of the patients treated with osteosynthesis, whereas 38% of those with retained fixation self-reported implant-related pain at least some of the time. Eight patients (20%) had an extensor lag greater than 5°. A restricted range of flexion of greater than 5° was noted in 15 patients (38%) and restricted range of extension of greater than 5° was noted in 6 patients (15%). Biodex dynamometric testing revealed a mean isometric extension deficit of 26% between the uninvolved and involved sides for peak torque. Extension power was also tested with an angular velocity of 90°/sec and 180°/sec and mean deficits of 31% and 29% were noted, respectively, when compared with the contralateral extremity.

CONCLUSIONS:
At a mean of 6.5 years after operative treatment for patella fractures, significant symptomatic complaints and functional deficits persist based on validated outcome measures as well as objective physical evaluations. This study fills a void in the literature regarding the functional outcomes of these patients. It also underscores the complexity associated with treating this common fracture and should help guide surgeons to better counsel patients on the expected long-term function after operative treatment of patella fractures.

LEVEL OF EVIDENCE:
Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.