Post-traumatic instability of the knee may lead to substantial impact on quality of life and physical functioning that requires surgical intervention1,2. The utilization of autografts is a popular option for cruciate ligament reconstruction, and hamstring tendons are the most frequently harvested3. These autografts have been used for both anterior and posterior cruciate ligament reconstructions3. One of the rare but recognized complications, however, is injury to the infrapatellar branch of the saphenous nerve during harvesting of the graft4-7. Mechanisms of injury include laceration of the nerve during the skin incision or disruption of the nerve during deeper dissection whilst performing the graft harvest4-7.
Authors have reported saphenous nerve injury rates as high as 70% during autograft harvesting for ligament reconstruction4. However, based on the literature to date, few studies have highlighted the risk of injury to the sciatic nerve itself from the tendon stripper. This is a case report involving injury to the common peroneal nerve fascicles of the sciatic nerve whilst performing a contralateral hamstring harvest for a posterior cruciate ligament repair.
The patient was informed that data concerning the case would be submitted for publication, and he provided consent.
A 22-year-old man sustained a left lateral tibial plateau fracture along with ruptures of the medial collateral and posterior cruciate ligament following a sporting injury. Whereas the tibial plateau fracture was managed nonoperatively, he underwent repair of the medial collateral ligament and reconstruction of the posterior cruciate ligament with a hamstring autograft. This was harvested from the contralateral side 5 months following injury. The operating surgeon was a consultant orthopedic surgeon with an assistant. Following this procedure, the patient developed an acute right-sided foot drop. Original operative records stated that the hamstring harvest of both the gracilis and semitendinousus was undertaken with a tourniquet time of less than 20 minutes and the graft taken from the level of the pes anserinus via a longitudinal incisional without any complications noted at the time.
Examination following the ligament reconstruction demonstrated Medical Research Council (MRC) grade 0 in extensor hallicus longus, extensor digitorum longus, and tibialis anterior, with no light touch sensation present over the first dorsal web-space. The function of the tibial nerve was preserved throughout and there was no development of any neuropathic pain. A positive Tinel sign was present in the posterior thigh. Electromyography studies were preformed preoperatively and demonstrated an acute, partial right common peroneal nerve lesion. Due to the lack of recovery, the patient was subsequently referred to our tertiary referral center specializing in peripheral nerve injuries.
Seen in clinic 2 months following this procedure, the decision was made to proceed with an exploration of the right sciatic, tibial, and common peroneal nerves. This occurred at around 8 months following his initial injury and 3 months following his ligamentous repair. Intraoperatively, both the common peroneal and tibial nerves were defined along it from their passage at the popliteal fossa to their bifurcation of fascicles from the sciatic nerve. Both nerves were in continuity with no evidence of scarring or presence of neuromas.
Therefore, the sciatic nerve containing at this point both the fascicles of the common peroneal and tibial nerves was explored to a level 20 cm proximal to the head of the fibula. A lesion in continuity was identified at this level with firm consistency and discoloration over a length of approximately 5 cm and with around 20% increased diameter compared to the normal caliber of the nerve (Fig. 1). Intraoperative cross-lesional nerve stimulation demonstrated good activity in the tibial nerve but reduced activity in the common peroneal nerve. The sciatic nerve was thoroughly neurolyzed across the full extent of the lesion. The immediate postoperative recovery was uncomplicated and follow-up at 1-year clinical review demonstrated MRC Grade 4 in tibialis anterior muscle extensor pollicis longus and 3 in extensor hallucis longus. He utilized a foot drop splint as functionally had a residual foot-drop gait.
Injury to the sciatic nerve and the fascicles of the common peroneal nerve following harvesting of hamstring tendons has been reported previously8. A case by Vardi describes an ipsilateral hamstring harvest for anterior cruciate ligament reconstruction that resulted in a conservatively managed foot drop that resolved spontaneously with almost full functional recovery at 1-year postoperatively8.
In this case study, the injury arose from the hamstring harvest on the contralateral side to the ligamentous repair. Intraoperative localization of the neuroma corresponded with the likely position of the tendon stripper tip within the posterior thigh. The degenerative lesion of the common peroneal fascicles of the sciatic nerve found intraoperatively and supported by the preoperative electromyography is unlikely to have been caused by any pressure effects related to patient positioning or by the relatively short tourniquet time.
The risk of injury to the saphenous nerve from both the skin incision and deep dissection during hamstring tendon harvest has been well-documented6,9. Luo et al. recommended an oblique incision rather than a vertical one to avoid inadvertent damage to the saphenous nerve9. Charalambous and Kwaees suggest an alternative strategy with positioning of the knee in 90° flexion and the hip in external rotation to reduce the risk of nerve injury6,9. Based on the extensive literature highlighting the risk of injury to the saphenous nerve and recommendations to position the knee in a “figure-of-4” position to avoid the lateral subcutaneous region, there may be a tendency for the tendon stripper to stray toward the midline, inadvertently damaging the sciatic nerve8.
To the best knowledge, this is only the second reported case of an iatrogenic injury to the sciatic nerve following hamstring harvesting and the only case confirmed with intraoperative findings. Although this complication is rare, based on the substantial disability conferred by a potential sciatic nerve injury, orthopedic surgeons should be cognizant of this problem when harvesting hamstring autografts. Whilst saphenous nerve injuries are not uncommon in these procedures, more junior surgeons or indeed experienced surgeons should be aware that guiding the tendon strippers toward the midline might place the sciatic nerve at increased risk of injury. Furthermore, it is safer to orient the cutting edge toward the medial thigh skin when harvesting the hamstring proximally, thus minimizing the risk to the sciatic nerve. We would recommend the surgeon be familiar with the equipment and kit used in the harvesting of the hamstrings especially keeping the tendon stripper closed until required. With these technical considerations in mind, we would hope that injury to the sciatic nerve in hamstrings harvesting remains a rare complication.
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8. Vardi G. Sciatic nerve injury following hamstring harvest. Knee. 2014;11(1):37-9.
9. Luo H, Yu JK, Ao YF, Yu CL, Peng LB, Lin CY, Zhang JY, Fu X. Relationship between different skin incisions and the injury of the infrapatellar branch of the saphenous nerve during anterior cruciate ligament reconstruction. Chin Med J (Engl). 2007;120(13):1127-30.