Frequency of infrapatellar neuropathy post-total knee replacement and arthroscopic surgery in Egyptian patients

Background The infrapatellar branch of the saphenous nerve (IPBSN) contains only sensory fibers that innervate the knee regarding its anteromedial aspect and the anterior-inferior portion of its capsule. IPBSN damage has been recorded as a postoperative complication of surgery about the knee, which is manifested by pain, numbness and reflex sympathetic dystrophy. The incisions made for arthroscopy, medial arthrotomy, and anterior cruciate ligament surgery also, can causes IPBSN damage in about 0.5 to 30% of cases. We aimed to study the frequency of infrapatellar branches of the saphenous nerve entrapment/injured in Egyptian patients to find the incidence of its affection in post-operative knee surgeries and to increase the awareness of this condition. Results Ninety patients complaining pain at the antero-medial aspect of the knee were collected and divided into 3 groups: G1 included 30 patients with a history of total knee replacement, G2 included 30 patients with a history of knee arthroscopy and G3 included 30 patients with non-specific knee pain. All patients went to clinical, electrophysiological study and laboratory measures. There was a significant statically differences of sensory nerve conduction study regarding latency and amplitude of infrapatellar nerve between the three groups and significant statically differences of clinical signs among patients of the studied groups regarding Hofmann-Tinel sign and pain provocation test. Conclusion The entrapment/injury of IPBSN is an underestimated sometimes unrecognized cause of post-operative knee pain to many clinicians. Awareness of this condition would probably help in managing these cases to decrease post-operative pain and disability as the frequency of infrapatellar neuropathy post total knee replacement was 56.6% and post arthroscopic surgery was 63.3% in cohort of Egyptian patients.