Surgically treated acute distal biceps tendon injuries: What results do they have in comparison with the contralateral healthy arm? A systematic review and meta-analysis

Background: Surgical repair of distal biceps tendon injury restores flexion and supination strength, resulting in good functional outcome. There are few studies that consider clinical results of the operated arm compared to the healthy contralateral arm, whereas there are many articles examining the results of different surgical techniques. We carried out a systematic review with meta-analysis of the studies that consider this comparison. The aim was to evaluate if there are significative differences in terms of functional results between the operated arm and the non-injured contralateral arm. In fact, we believe that this comparison is useful for assessing patient true satisfaction. Patients and methods: In accordance with the PRISMA and QUORUM statements, a comprehensive search on PubMed, Scopus, Embase, Cochrane, Google Scholar and Web of Science databases was conducted to identify studies reporting comparative functional results of the operated arm with healthy contralateral arm from January 1985 until November 2022. Criteria for inclusion were acute complete injury of the distal biceps' tendon operated within 30days; range of motion (ROM), isokinetic and isometric strength measurements; minimum patients follow-up of 24months; studies written in English language. Then a DerSimonian and Laird meta-analysis was conducted to compare the functional outcomes of the operated arm to the non-injured arm. Results: Of the 588 initial studies, 18 studies met the inclusion criteria; methodological quality was assessed using the Newcastle-Ottawa scale. A total of 272 surgically treated distal biceps ruptures were included in the study. The mean follow-up time was of 39.6months (24 to 72months). ROM flexion, pronation, and supination of the operated elbows were significantly decreased, with mean differences of -1.24̊ (p=0.004), -7.95̊ (p=0.003), and -9.27̊ (p=0.004) respectively, compared to the non-injured healthy elbows. The difference of ROM extension was not-statistically significant (+0.21̊; p=0.66). The Isokinetic data showed a statistically significant reduction in the flexion strength (-4.56Nm; p=0.0004) and a statistical significative reduction in the supination strength (-1.18 Nm; p=0.02) of the injured operated arm compared with the healthy one. The forest-plot table of the isometric data was not elaborated due to the small number of studies eligible for the meta-analysis. Discussion: This study represents the first systematic review and meta-analysis to compare functional and clinical outcomes following operative treatment of distal biceps tendon ruptures with the contralateral healthy arm. Significant differences in ROM flexion, supination, and pronation and in isokinetic and isometric data were found between the operated and non-operated unaffected arm, demonstrating that, as expected, the unaffected arm performed better than the operated one. However, the functional differences between the data of the operated and healthy arm were slight and lead us to overall consider surgery as good functional result. Levels of evidence: III.