HamRepair: Clinical and functional outcomes at least 2 years after hamstring muscle repair – a pilot study

Several studies from the past 10 years have shown a significant subjective benefit after a surgical treatment in comparison to a conservative treatment of a proximal hamstring rupture.4-7 There is also a strong evidence of about 10% decrease in muscle strength in comparison to the non operated site4,13. Similar muscle strength between the operated and contralateral side was observed up to 10 years after repair.14 However, to the best of our knowledge there is a lack of evidence in possible development of biomechanical and functional limb asymmetries including muscle activity caused by these postoperative muscular imbalances. Our project will therefore concentrate on the biomechanics of gait and daily activity tasks and investigate differences between the operated and contralateral limb. Primarily we will quantify potential muscular deficits between limbs and compare these to the findings of the gait pattern. If proven right and limping does occur, it can, on the long run, cause earlier onset of skeletal degeneration and osteoarthritis.8-10 As the mean age of the patients examined in the studies with hamstring rupture is usually about 40 to 45 years6 and the average life expectancy is above 80 years11, potential muscular deficits may manifest as pathological gait that may predispose these patients to premature and potentially more severe degenerative processes. For instance, it is possible that the risk of hip osteoarthritis and/or lower back or iliosacral joint osteoarthritis is higher in patients after a hamstring rupture. Therefore, improving the understanding of biomechanical and functional outcome after hamstring repair is critical, and potential deficits may be prevented with additional physiotherapy addressing muscular imbalances. In the proposed pilot study, we will compile outcome data on the outcome of a new, intraoperative lateral positioning of the anchors on the tuber ischiadicum, as was used in all of our patients, in comparison to regular anatomical anchoring direct on top of the tuber ischiadicum.12 Based on our clinical experience many patients describe a local discomfort in seated position with traditional anchor positioning, and a lateral positioning could potentially prevent this complaint as the lateral area of os ischi is not exposed to the pressure when seated. With this pilot study we will not only provide new insights into the postoperative function of the hamstrings with corresponding gait pattern for the current patients, but also possibly prevent the discomfort while sitting by changing anchor placement in future patients. Further, the data obtained in this study will facilitate proper sample size calculations for future clinical trials.