Scapholunate and lunotriquetral joint dynamic stabilizers and their role in wrist neuromuscular control and proprioception.

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.

Influence of forearm rotation on the kinetic stabilizing efficiency of the muscles that control the scapholunate joint. Clinical application in proprioceptive and neuromuscular rehabilitation programs.

BACKGROUND: This study focuses on the relationship between forearm muscles, carpal ligaments, and their impact on scapholunate joint stability across varying forearm rotations. This is crucial for optimizing pre and postoperative rehabilitation strategies for scapholunate joint dysfunction. PURPOSE: Our study aims to understand the kinetic influence of forearm muscles on scapholunate joint instability. We emphasize the significance of forearm rotation to enhance treatment efficacy. STUDY DESIGN: We conducted an experimental study to understand how forearm muscles contribute to the stability of the scapholunate joint during different degrees of forearm rotation and we focused on the joint effect of muscle groups rather than individual muscles for treatment protocols. RESULTS: Our findings shed light on the conservative treatment of dynamic scapholunate instability and the postoperative rehabilitation of scapholunate ligament repair. We found that the effect of forearm muscles significantly contributes to preserve stability in the scapholunate joint across various forearm rotational positions. These insights have practical implications for hand therapists, offering innovative strategies to enhance clinical practice. CONCLUSIONS: This research underscores the importance of considering forearm rotation when developing rehabilitation protocols for scapholunate joint instability and provides a valuable perspective in line with current rehabilitation principles.

Bilateral Ulnar Deviation Supination Stress Test to Assess Dynamic Scapholunate Instability.

PURPOSE: We describe a new radiologic test to assess the integrity of the scapholunate ligament in dynamic scapholunate dysfunction. METHODS: A bilateral forearm-holding device was designed to perform a comparative radiographic assessment of the scapholunate joint gap during resisted isometric contraction of the extensor carpi ulnaris muscle with full supination of the forearm. The concept is based on the known scaphoid pronation effect of this muscle. Clinical data from 12 patients were collected retrospectively and used to analyze the patients' symptomatic and asymptomatic (contralateral) wrists with a newly developed test called the Bilateral Ulnar Deviation Supination (BUDS) test. A wrist arthroscopy was performed in all cases as a reference standard for the radiologic test. RESULTS: The test was positive in 7 patients, with a mean scapholunate joint gap of 4.8 mm. The mean differences in the scapholunate joint gaps between both wrists were 2.6 mm in BUDS-positive patients and 0.2 mm in BUDS-negative patients. A Geissler stage III or IV scapholunate ligament rupture was confirmed in all BUDS-positive patients; by contrast, BUDS-negative patients exhibited either no lesion or a Geissler stage I injury. CONCLUSIONS: The BUDS test is a new radiologic test based on proven biomechanical effects that is able to accurately assess dynamic scapholunate dysfunctions. The analysis carried out found a correlation between radiographic and arthroscopic findings. Further research is needed to confirm the validity and reliability of the test. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic III.

The impact of COVID-19 pandemic on hand surgery: a FESSH perspective.

COVID-19 has affected us all. The following collection of short essays highlights various aspects of the pandemic and how it has impacted hand surgery and lessons learned, from the perspective of the Federation of European Societies for Surgery of the Hand (FESSH) Executive Committee members. A range of topics were individually chosen by each of the five committee members and presented.

Degeneration of the articular disc in the human triangular fibrocartilage complex.

INTRODUCTION: Traumatic injuries of the triangular fibrocartilage complex (TFCC) are frequent reasons for ulnar wrist pain. The assessment of the extent of articular disc (AD) degeneration is important for the differentiation of acute injuries versus chronic lesions. MATERIALS AND METHODS: The AD of the TFCC of eleven human cadaver wrists was dissected. Degeneration was analyzed according to the grading of Krenn et al. Hematoxylin-eosin was used to determine the tissue morphology. Degeneration was evaluated using the staining intensity of alcian blue, the immunohistochemistry of the proteoglycan versican and the immunoreactivity of NITEGE, an aggrecan fragment. RESULTS: The staining homogeneity of HE decreased with higher degeneration of the AD and basophilic tissue areas were more frequently seen. Two specimens were characterized as degeneration grade 1, five specimens as grade 2, and four specimens as grade 3, respectively. Staining intensity of alcian blue increased with higher degeneration grade of the specimens. Immunoreactivity for NITEGE was detected around tissue fissures and perforations as well as matrix splits. Immunoreactivity for versican was found concentrated in the tissue around matrix fissures and lesions as well as loose connective tissue at the ulnar border of the AD. Specimens with degeneration grade 2 had the strongest immunoreactivity of NITEGE and versican. Cell clusters were observed in specimens with degeneration grade 2 and 3, which were stained by alcian blue and immunoreactive for NITEGE and versican. Increasing age of the cadaver wrists correlated with a higher degree of degeneration (p < 0.0001, r = 0.68). CONCLUSIONS: The fibrocartilage of degenerated ADs contains NITEGE and versican. The amount of the immunoreactivity of these markers allows the differentiation of degenerative changes into three grades. The degeneration of the AD increases with age and emphasizes its important mechanical function.

Volar Plate Fixation to Treat Scaphoid Nonunion: A Case Series With Minimum 3 Years of Follow-Up.

PURPOSE: Several options exist for treating scaphoid nonunion. For selected cases, some authors recommend using a volar buttress plate. The aim of the study was to report the clinical and radiological outcomes achieved at a minimum of 3 years' follow-up of treating scaphoid nonunion with a scaphoid volar plate. METHODS: We retrospectively reviewed 15 patients with symptomatic scaphoid nonunion treated with scaphoid plate osteosynthesis and a bone graft from the volar aspect of the distal radius between January 2011 and November 2013. The patients' average age was 32 years (range, 21-62 years). No patient had undergone previous scaphoid surgery. Clinical assessments included wrist range of motion (ROM), grip strength, and a 10-point visual analog scale rating of pain. Further subjective assessment was performed using validated measurement tools. All patients underwent plain radiography with 6 different views and computed tomography before and after surgery. The scapholunate angle was measured to evaluate carpal alignment. RESULTS: The mean follow-up period was 42 months (range, 36-51 months). Bone union was obtained in 13 of 15 patients (87%) at an average of 5 months (range, 3-8 months) after surgery. Significant improvements in the scapholunate angle and visual analog scale pain score were observed. However, both wrist ROM and grip strength remained significantly decreased relative to the opposite side (62% and 55% of normal, respectively). Four patients experienced hardware complications: plate breakage (1 scaphoid) and screw back-out (3 scaphoids). Impingement between the radial styloid and the scaphoid plate was identified in 6 patients. Five patients required additional surgery to remove the plate. CONCLUSIONS: Our study indicates unsatisfactory results treating scaphoid nonunion with a volar scaphoid plate. Although the rate of union was comparable with that of other series, we noted more complications. We are concerned about both the high proportion of hardware complications and required secondary surgical procedures. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.

Role of muscles in the stabilization of ligament-deficient wrists.

This article reviews the results of a series of cadaver investigations aimed at clarifying the role of muscles in the stabilization of ligament-deficient wrists. According to these studies, isometric contraction of some forearm muscles induces midcarpal (MC) supination (ie, the abductor pollicis longus, extensor carpi radialis longus, and flexor carpi ulnaris), whereas other muscles induce MC pronation (ie, the extensor carpi ulnaris). Because MC supination implies tightening of the volar scaphoid-distal row ligaments, the MC supination muscles are likely to prevent scaphoid collapse of wrists with scapholunate ligament insufficiency. MC pronator muscles, by contrast, would be beneficial in stabilizing wrists with ulnar-sided ligament deficiencies owing to their ability to tighten the triquetrum-distal row ligaments. Should these laboratory findings be validated by additional clinical research, proprioceptive reeducation of selected muscles could become an important tool for the treatment of dynamic carpal instabilities.

Surgical Decompression of Exertional Compartment Syndrome of the Forearm in Professional Motorcycling Racers: Comparative Long-term Results of Wide-Open Versus Mini-Open Fasciotomy.

OBJECTIVE: To compare the long-term results of 2 surgical techniques for forearm chronic exertional compartment syndrome (CECS) in professional motorcycling racers and to study a new diagnostic variable for CECS, TRest. DESIGN: Retrospective case series. LEVEL OF EVIDENCE: 4. SETTING: University Hospital. PARTICIPANTS: Thirty-four patients identified from a surgical database who had been operated on for upper-limb CECS. INTERVENTIONS: The purpose of the study was to report and compare the long-term results of 2 surgical techniques using fasciotomies [wide-open fasciotomy (WOF) versus mini-open fasciotomy (MOF)] for forearm CECS in professional motorcycling racers. PATIENT CHARACTERISTICS: Pain [visual analog scale (100-point scale)] and functional scores (Quick-DASH) at 3 months after surgery and at regular intervals during clinical visits. Surgical complications: Level of satisfaction with the outcome. Time to return to full activity after surgery. RESULTS: Thirty-four racers, 22 with bilateral involvement (n = 56), were diagnosed with CECS and were treated either with WOF (n = 24) or MOF (n = 32) depending on the surgeon's indication. Mini-open fasciotomy was usually selected in cases who need a faster recovery because of competition schedule. Visual analog scale and Quick-DASH improved 63 and 73 points, respectively (P < 0.001) with no significant difference between both surgical methods (P = 0.512). Both WOF and MOF were equally effective. Ninety-four percent of the patients were satisfied after 45.35 ± 12 months of follow-up, with no significant difference between surgical groups (P = 0.642). The time to return to full activity was 2.7 ± 1 week, also with no significant difference (P = 0.544). The time between when the stress testing was halted for pain and the return to baseline pressure (TRest) was superior to 15 minutes (defined as the mean minus 2 SDs) in 100% patients. CONCLUSIONS: Surgical open or mini-invasive fasciotomy is equally successful in motorcycling racers with forearm CECS. Although the sensitivity of TRest is quite high in our series, further studies are still needed to validate its diagnostic value. CLINICAL RELEVANCE: Surgical open or mini-invasive fasciotomy is equally successful in motorcycling racers with forearm CECS.

Immunohistochemical Mapping of Sensory Nerve Endings in the Human Triangular Fibrocartilage Complex.

BACKGROUND: The triangular fibrocartilage complex is the main stabilizer of the distal radioulnar joint. While static joint stability is constituted by osseous and ligamentous integrity, the dynamic aspects of joint stability chiefly concern proprioceptive control of the compressive and directional muscular forces acting on the joint. Therefore, an investigation of the pattern and types of sensory nerve endings gives more insight in dynamic distal radioulnar joint stability. QUESTIONS/PURPOSES: We aimed to (1) analyze the general distribution of sensory nerve endings and blood vessels; (2) examine interstructural distribution of sensory nerve endings and blood vessels; (3) compare the number and types of mechanoreceptors in each part; and (4) analyze intrastructural distribution of nerve endings at different tissue depth. METHODS: The subsheath of the extensor carpi ulnaris tendon sheath, the ulnocarpal meniscoid, the articular disc, the dorsal and volar radioulnar ligaments, and the ulnolunate and ulnotriquetral ligaments were dissected from 11 human cadaver wrists. Sensory nerve endings were counted in five levels per specimen as total cell amount/cm(2) after staining with low-affinity neurotrophin receptor p75, protein gene product 9.5, and S-100 protein and thereafter classified according to Freeman and Wyke. RESULTS: All types of sensory corpuscles were found in the various structures of the triangular fibrocartilage complex with the exception of the ulnolunate ligament, which contained only Golgi-like endings, free nerve endings, and unclassifiable corpuscles. The articular disc had only free nerve endings. Furthermore, free nerve endings were the predominant sensory nerve ending (median, 72.6/cm(2); range, 0-469.4/cm(2)) and more prevalent than all other types of mechanoreceptors: Ruffini (median, 0; range, 0-5.6/cm(2); difference of medians, 72.6; p < 0.001), Pacini (median, 0; range, 0-3.8/cm(2); difference of medians, 72.6; p < 0.001), Golgi-like (median, 0; range, 0-2.1/cm(2); difference of medians, 72.6; p < 0.001), and unclassifiable corpuscles (median, 0; range, 0-2.5/cm(2); difference of medians, 72.6; p < 0.001). The articular disc contained fewer free nerve endings (median, 1.8; range, 0-17.8/cm(2)) and fewer blood vessels (median, 29.8; range, 0-112.2/cm(2); difference of medians: 255.9) than all other structures of the triangular fibrocartilage complex (p ≤ 0.001, respectively) except the ulnolunate ligament. More blood vessels were seen in the volar radioulnar ligament (median, 363.62; range, 117.8-871.8/cm(2)) compared with the ulnolunate ligament (median, 107.7; range, 15.9-410.3/cm(2); difference of medians: 255.91; p = 0.002) and the dorsal radioulnar ligament (median, 116.2; range, 53.9-185.1/cm(2); difference of medians: 247.47; p = 0.001). Free nerve endings were obtained in each structure more often than all other types of sensory nerve endings (p < 0.001, respectively). The intrastructural analysis revealed no differences in mechanoreceptor distribution in all investigated specimens with the numbers available, showing a homogenous distribution of proprioceptive qualities in all seven parts of the triangular fibrocartilage complex. CONCLUSIONS: Nociception has a primary proprioceptive role in the neuromuscular stability of the distal radioulnar joint. The articular disc and ulnolunate ligament rarely are innervated, which implies mainly mechanical functions, whereas all other structures have pronounced proprioceptive qualities, prerequisite for dynamic joint stability. CLINICAL RELEVANCE: Lesions of the volar and dorsal radioulnar ligaments have immense consequences not only for mechanical but also for dynamic stability of the distal radioulnar joint, and surgical reconstruction in instances of radioulnar ligament injury is important.

How to Avoid Ulnar Nerve Injury When Setting the 6U Wrist Arthroscopy Portal.

The dorsal sensory branch of the ulnar nerve (DSBUN) is at risk in setting the 6U wrist arthroscopy portal. Although surgeons know the risk and are careful when they set the 6U portal, DSBUN injuries still occur. The purpose of the present anatomical study was to evaluate the possibility that DSBUN undergoes dynamic anatomical variations in its location during wrist arthroscopy. The goal of the study was to clarify (1) whether the nerve-to-portal (NTP) distance changes with flexion/extension wrist and/or hand/forearm rotation, and (2) whether there is any particular combination of flexion-extension/hand-forearm rotation where the NTP distance is maximal. Six fresh cadaver arms were suspended in a traction tower with forearm rotation locked, the skin and subcutaneous tissue around the ulnar head was removed, and the NTP distance measured in three predetermined loading/positional conditions. Of all options, the one that consistently showed the longest and safest NTP distance involved wrist flexion and radiocarpal supination when forearm rotation is limited. In conclusion, when an arthroscopic traction device restricts the forearm rotation, the 6U portal should not be set under traction with the hand passively pronated. Failure to observe this precaution can result in serious neuropathic pain.

New surgical approach to advanced Kienböck disease: lunate replacement with pedicled vascularized scaphoid graft and radioscaphoidal partial arthrodesis.

Reconstructive procedures such as proximal row carpectomy or partial arthrodesis have been commonly proposed for advanced Kienböck disease (Lichtmann IIIB to IV). The purpose of this study is to evaluate an alternative surgical technique to advanced Kienböck disease: lunate excision and replacement with pedicled vascularized scaphoid graft and partial radioscaphoidal arthrodesis. The main advantage of the proposed intervention is to preserve mobility while not jeopardizing prime clinical outcomes such as pain. By replacing the devitalized lunate we aim at maintaining midcarpal range of motion, and preventing disease progression with carpal collapse and osteoarthritis of the wrist. Between 2002 and 2008, 13 patients of mean age 41 years (range, 25 to 57 y) were operated using this technique. The surgical act included 3 key steps. First, we excised the lunate, then, filled the generated gap with the rotated scaphoid, using it as a pedicled vascularized autograft. Finally, we performed a partial radioscaphoid arthrodesis. At the final follow-up, none of the intervened patients had pain at rest, and 6 patients could perform nonrestricted daily activities. The average postoperative range of motion in flexion/extension was 70 degrees (range, 55 to 90 degrees), 44% (range, 38% to 54%) of what could be achieved by the contralateral arm, and only 16% (range, 14% to 19%) or 25 degrees (range, 18 to 30 degrees) less than the preoperative range of motion of the same wrist. Grip strength improved by more than 30% (range, 24% to 36%). At an average follow-up of 4 years after surgery, 12 of 13 patients had no radiographic evidence of osteoarthritis or collapse of subchondral bone at the level of the new scaphocapitate joint. At follow-up evaluation, the average DASH score was 14 points (range, 6 to 20). The patients experienced a significant improvement in their functional abilities, achieving good results compared with the conventional techniques. The absence of carpal collapse and good functional results are encouraging.

Arthroplasty of the scaphoid-trapezium-trapezoid and carpometacarpal joints.

Resection arthroplasty is an old, and yet reliable, solution for the isolated osteoarthritis (OA) of some joints of the hand. With complication low rates, this technically undemanding option is ideal for scapho-trapezial-trapezoidal joint OA, as well as for the OA of the carpometacarpal joints of the fingers. This paper reviews its indications, surgical technique, and results.

Bizarre Parosteal Osteochondromatous Proliferation (Nora's Lesion) of the Hand: A Report of Two Atypical Cases.

Bizarre parosteal osteochondromatous proliferation (BPOP), also called Nora's lesion, is an unusual, benign, bony lesion frequently found in the hand. Originally, two of the key radiological features used to describe such lesions were: (1) a lack of corticomedullar continuity and (2) an origin from the periosteal aspect of an intact cortex. The authors present 2 unique cases of histologically proven BPOP in which the integrity of the cortex was affected. In the first case there was medullary continuity, and in the second case there was saucerization of the underlying cortical bone. The authors support that simple X-ray evaluation is insufficient to diagnose BPOP in atypical cases. Careful axial CT scanning or MRI may prove helpful. Taking into account these new notions, histopathology gains greater importance as a diagnostic tool for this particular group of entities.

Etiology of Kienböck disease.

The etiology of Kienböck disease is still unknown and, consequently, the ideal treatment is in doubt. Many different hypotheses have been suggested. There are reasons to believe that there are mechanical, vascular, and metabolic factors predisposing to the disease, and probably some factors triggering the development of the process. Among mechanical factors, the short ulna has been thought to be the most relevant. However, presently there are insufficient data to support a significant association between negative ulnar variance and Kienböck disease. With regard to vascular factors, anatomical studies have shown consistent dorsal and palmar arteries entering the bone, and thus, the most likely site for vascular impairment may be at the subchondral level. Many triggering factors have been proposed during the past years, but until this is truly clarified, finding the real cause of Kienböck disease will continue to be a real challenge.