Interventions for treating fractures of the patella in adults.

BACKGROUND: Fractures of the patella (kneecap) account for around 1% of all human fractures. The treatment of these fractures can be surgical or conservative (such as immobilisation with a cast or brace). There are many different surgical and conservative interventions for treating fractures of the patella in adults.

OBJECTIVES: To assess the effects (benefits and harms) of interventions (surgical and conservative) for treating fractures of the patella in adults.

SEARCH METHODS: We searched the Cochrane Bone, Joint and Muscle Trauma Group Specialised Register (2 May 2014), the Cochrane Central Register of Controlled Trials (The Cochrane Library, 2014, Issue 4), MEDLINE (1946 to April Week 4 2014), Ovid MEDLINE In-Process & Other Non-Indexed Citations (2 May 2014), Embase (1980 to 2014 Week 17), LILACS (1982 to 2 May 2014), trial registers and references lists of articles.

SELECTION CRITERIA: Randomised controlled trials (RCTs) or quasi-RCTs that evaluated any surgical or conservative intervention for treating adults with fractures of the patella were eligible for inclusion. The primary outcomes were patient-rated knee function and knee pain, and major adverse outcomes.

DATA COLLECTION AND ANALYSIS: At least two review authors independently selected eligible trials, assessed risk of bias and cross-checked data extraction. Where appropriate, results of comparable trials were pooled.

MAIN RESULTS: We included five small trials involving 169 participants with patella fractures. Participant age ranged from 16 to 76 years. There were 68 females and 100 males; the gender of one participant was not reported. Two trials were conducted in China and one each in Finland, Mexico and Turkey.All five trials compared different surgical interventions. Two trials compared biodegradable versus metallic implants for treating displaced patella fractures; one trial compared patellectomy with advancement of vastus medialis obliquus versus simple patellectomy for treating comminuted patella fractures; and two trials compared percutaneous osteosynthesis (both procedures were 'novel' and one used a new device) versus open surgery for treating displaced patella fractures. All the trials had design flaws, such as lack of assessor blinding, which put them at high risk of bias, potentially limiting the reliability of their findings. No trial reported on health-related quality of life, return to previous activity or cosmetic appearance.Very low quality evidence from two trials (48 participants) comparing biodegradable versus metallic implants indicated little difference between the two interventions at two-year follow-up in the numbers of participants with occasional knee pain (1/23 versus 2/24), incurring adverse events (3/24 versus 1/24) or with reduced knee motion (2/23 versus 2/24). Neither trial reported patient-rated knee function scores. In one trial, as per routine practice, metallic implants were removed one year after surgery (four participants). The other trial did not report on this aspect.Very low quality evidence from one trial (28 participants) indicated that compared with simple patellectomy, patellectomy with advancement of vastus medialis obliquus surgery for treating comminuted patella fractures resulted in more participants with a 'good' result based on a subjectively rated score (12/12 versus 11/16; risk ratio (RR) 1.42, 95% confidence interval (CI) 1.01 to 2.01), fewer participants experiencing knee pain (5/12 versus 13/16; RR 3.11, 95% CI 1.01 to 9.60) and more participants with unlimited activity and no loss in quadriceps strength at four-year follow-up. The only adverse event reported was a patellar tendon subluxation in the simple patellectomy group.Neither trial comparing percutaneous osteosynthesis (using novel devices or methods) versus open surgery reported on patient-rated knee function scores. Very low quality evidence from two trials (93 participants) showed that percutaneous osteosynthesis improved knee pain measured using visual analogue scale (0 to 10 where 10 is worst pain) at one month (mean difference (MD) -2.24, 95% CI -2.80 to -1.68) and at up to three months (MD -1.87, 95% CI -2.45 to -1.29). This effect did not persist at six months (very low quality evidence from one trial). Very low quality evidence from the two trials showed significantly fewer participants with adverse events (loss of reduction, infection, hardware complications, delayed wound healing) after percutaneous surgery (8/47 versus 28/46; RR 0.28, 95% CI 0.14 to 0.55). Very low quality evidence from the two trials indicated better clinician-rated knee function scores after percutaneous fixation at two to three months and 12 months follow-up; however, the between-group difference was not clinically important at 24 months. Very low quality evidence showed a lower incidence of hardware removal in the percutaneous group at two years; however, the results in the two trials were heterogeneous and the reasons for removal were not given in detail.

AUTHORS' CONCLUSIONS: There is very limited evidence from RCTs about the relative effects of different surgical interventions for treating fractures of the patella in adults. There is no evidence from RCTs evaluating the relative effects of surgical versus conservative treatment or different types of conservative interventions.Based on very low quality evidence, biodegradable implants seem to be no better than metallic implants for displaced patellar fractures; patellectomy with vastus medialis obliquus advancement may give better results than simple patellectomy for comminuted patellar fractures; and two novel methods of percutaneous osteosynthesis may give better results than conventional open surgery. However, until conclusive evidence becomes available, treatment options must be chosen on an individual patient basis, carefully considering the relative benefits and harms of each intervention and patient preferences. Further randomised trials are needed, but in order to optimise research effort, these should be preceded by research that aims to identify priority questions.