ABSTRACT
BACKGROUND: Recent research interest has grown in exploring the role of muscles, isometric contraction, proprioception, and neuromuscular control in addressing dynamic scapholunate and lunotriquetral joint instability, marking a shift in the understanding of wrist stability. PURPOSE: To present a comprehensive review of the carpal ligaments anatomy and wrist biomechanics, with a particular focus on the role of proprioception in dynamic carpal stability and their role in managing scapholunate (SL) and lunotriquetral (LTq) dynamic instabilities. STUDY DESIGN: We conducted a systematic search of the literature and review of the most relevant papers published and indexed in pubmed, related to wrist biomechanics, proprioception and its contribution to carpal dynamic stability. METHODS: The study involved a comprehensive review of neuromuscular mechanisms in dynamic stabilization of the carpus, based on cadaver studies. The 3D position of the scaphoid, triquetrum, and capitate was monitored before and after tendon loading. RESULTS: The extensor carpi ulnaris (ECU) and the flexor carpi radialis (FCR) are identified as the primary pronators of the midcarpal joint. The ECU's pronation effect can potentially strain the scapholunate ligament, while the supinator muscles, the abductor pollicis longus (APL), the extensor carpi radialis longus (ECRL), and the flexor carpi ulnaris (FCU), have a protective role, particularly in cases of scapholunate ligament dysfunctions. The FCR, despite being a pronator of the distal row, has a beneficial effect as it provokes supination of the scaphoid. CONCLUSIONS: Comprehending carpal dysfunctions and instabilities hinges on understanding carpal anatomy and normal biomechanics. Proprioception, encompassing joint position sensation and neuromuscular control, is pivotal for stability. Biomechanical research informs tailored muscle strengthening for specific carpal issues. Supinator muscles should be strengthened for SL injuries, and ECU-focused strengthening and proprioceptive training are key for dynamic LTq instabilities. Ongoing research should delve into the intricate relationship between carpal ligaments, muscles, and proprioception to enhance wrist stability.
ABSTRACT
BACKGROUND: External fixator knee arthrodesis is a salvage procedure used primarily in cases of end-stage infected total knee replacement (iTKR). Stable fixation combined with bone-end compression is essential to achieve knee fusion, but providing sufficient stability can be challenging in the presence of severe bone loss. Our hypothesis is that using an external fixation biplanar configuration would bring about a fusion rate superior to that of a monolateral frame. METHODS: This study compares outcomes of biplanar external fixator knee fusion due to non-revisable iTKR with those of a historical cohort control study with patients managed with a monoplanar configuration. Primary endpoints were fusion rate, time to achieve bone fusion and infection eradication rate. Limb-length discrepancy, pain level, patient satisfaction and health-related quality of life were evaluated. RESULTS: A total of 29 knee fusion cases were included. In the biplanar group, infection was eradicated in 100% of the patients and fusion was achieved in all cases within an average of 5.24 months. In comparison, in the monolateral group, infection was eradicated in 86% of the cases and fusion was achieved in 81% of the patients after a mean of 10.3 months (p < 0.05). In both groups, postoperative pain was mild and patients expressed a high degree of satisfaction once fusion was achieved. CONCLUSIONS: According to our data, external fixation knee fusion is a useful limb-salvage procedure in end-stage cases of knee PJI. We conclude that a biplanar configuration can halve the time required to achieve solid bone fusion in such a complex scenario.