Nerve endings of the wrist joint: a preliminary report of the dorsal radiocarpal ligament

Causes, symptoms, and treatments of nerve entrapments around the elbow: Current concepts

The elbow is a joint extremely susceptible to stiffness, even after a trivial trauma. As for other joints, several factors can generate stiffness such as immobilisation, joint incongruity, heterotopic ossification, adhesions, or pain. Prolonged joint immobilisation, pursued to assure bony and ligamentous healing, represents the most acknowledged risk factor for joint stiffness. The elbow is a common site of nerve entrapment syndromes. The reasons are multifactorial, but peculiar elbow anatomy and biomechanics play a role. Passing from the arm into the forearm, the ulnar, median, and radial nerves run at the elbow in close rapport with the joint, fibrous arches and through narrow fibro-osseous tunnel. The elbow joint, in fact, has a large range of flexion which exposes nerves lying posterior to the axis of rotation to traction and those anterior to compression.

Wrist proprioception-An update on scientific insights and clinical implications in rehabilitation of the wrist

The field of wrist proprioception, as it relates to rehabilitation and surgery, has gone through a period of intense growth in the past decade. From being primarily focused on the function of the joint and ligaments in patients with wrist trauma or after wrist surgery, the understanding is now that of a greater complexity in treating not just the wrist but the hand and arm as a whole. Proprioception is derived from the Latin words "proprius" - belonging to (oneself) and "-ception" to sense. In other words, how to sense ourselves. To have a complete sense of self, multiple sensory afferents originating from joints, ligaments, muscles, tendons, nerves, skin, vision, and hearing work together to orchestrate a balanced integration of sensorimotor functions, with the true goal to perceive and adapt to the physical world around us. In this update on wrist proprioception, we review current developments in the understanding of proprioception, with an implication for our everyday work as hand therapists and hand surgeons. Each contributing sense-joint, ligaments, muscles, skin, and brain-will be reviewed, and the clinical relevance will be discussed. An updated wrist rehabilitation protocol is proposed where the therapist is guided to rehabilitate a patient after wrist trauma and/or surgery in 4 stages: (1) basic hand and wrist rehabilitation with a focus on reducing edema, pain, and scar formation; (2) proprioception awareness to improve the sense of joint motion and position; (3) conscious neuromuscular rehabilitation where isometric exercises of muscles that are beneficial for a particular injury are promoted, whereas others that are potentially harmful are avoided; and (4) unconscious neuromuscular rehabilitation with training of the reflex and joint protective senses.

Treatment of Early Undifferentiated Chronic Monoarthritis of the Wrist by Arthroscopic Wrist Synovectomy Combined with Partial Denervation

OBJECTIVE

Undifferentiated chronic monosecarthritis (UCMA) is a group of inflammatory joint diseases that has the potential to progress to other diseases and can seriously affect patients' quality of life. There is yet no unified consensus regarding treatment of UCMA. This study aimed to investigate the efficacy of arthroscopic synovectomy combined with partial wrist denervation in treating Larsen 1-3 UCMA.

METHODS

In this case series, we reviewed 14 patients with UCMA treated by arthroscopic synovectomy combined with partial denervation from February 2017 to June 2020. The mean duration of symptoms was 17.4 months (range, 4-60 months), and the mean follow-up was 13.3 months (range, 6-23 months). The anterior and posterior interosseous nerves were severed at the distal forearm, and the radiocarpal, midcarpal, and distal radial ulnar joint synovial membranes were arthroscopically resected at the wrist. The clinical evaluation indices included the visual analogue scale score (VAS) for pain, grip strength, range of (active) motion of the wrist, total active motion, and Mayo wrist score. Larsen's scoring method was used as the imaging evaluation index.

RESULTS

At the last follow-up, significant clinical improvements were observed in the visual analogue scale (VAS) score for pain (6.0 (5.0-6.3) vs 1.0 (1.0-2.3), P = 0.001) and Mayo wrist score (42.1 ± 9.7 vs 61.8 ± 12.3, P < 0.0001). No significant changes were found in grip strength (15.9 ± 4.5 vs 16.6 ± 4.7, P = 0.230) or the flexion-extension arc (58.9 ± 39.0 vs 64.3 ± 36.5, P = 0.317), although the mean and median did show positive changes. Among the three patients who showed progress in imaging, there was no significant difference in their pain and functional scores compared to those who did not progress. One patient underwent total wrist fusion 17 months after the operation.

CONCLUSION

Arthroscopic wrist synovectomy combined with partial wrist denervation can provide sustained pain relief and functional recovery for patients with Larsen 1-3 UCMA.

Anatomical Study of the Innervation of Triangular Fibrocartilage Complex and Distal Radioulnar and Radiocarpal Joints: Implications for Denervation

PURPOSE

Open and percutaneous denervation is an emerging technique for joint pain. This study investigated the course and distribution of the articular branches innervating the triangular fibrocartilage complex (TFCC), distal radioulnar joint (DRUJ), and radiocarpal joint (RCJ) relative to bony and soft tissue landmarks to guide wrist denervation procedures.

METHODS

Fourteen formalin-embalmed specimens were serially dissected to expose the origin, course, and distribution of articular branches innervating the TFCC, DRUJ, and RCJ. Bony and soft tissue landmarks to localize each articular branch were documented and visualized on a 3-dimensional reconstruction of the bones of the distal forearm and hand.

RESULTS

The TFCC was innervated by articular branches from the posterior interosseus nerve (10 of 14 specimens), dorsal cutaneous branch of the ulnar nerve (14 of 14 specimens), palmar cutaneous branch of the ulnar nerve (12 of 14 specimens), and medial antebrachial cutaneous nerve (9 of 14 specimens). The DRUJ was innervated by the posterior interosseus nerve (9 of 14 specimens) and anterior interosseus nerve (14 of 14 specimens). The RCJ was innervated by the posterior interosseus nerve (14 of 14 specimens), superficial branch of the radial nerve (5 of 14 specimens), lateral antebrachial cutaneous nerve (14 of 14 specimens), and palmar cutaneous branch of the median nerve (10 of 14 specimens).

CONCLUSIONS

Multiple nerves were found to innervate the TFCC, DRUJ, and RCJ. The relationship of anatomical landmarks to specific articular branches supplying the TFCC, DRUJ, and RCJ can inform selective denervation procedures based on the structural origin of pain.

CLINICAL RELEVANCE

The detailed documentation of the spatial relationship of the nerve supply to the wrist provides clinicians with the anatomical basis to optimize current, and develop new denervation protocols to manage chronic wrist pain.

Innervation of the wrist joint: Literature review and clinical implications

The aim of this study was to review the literature on the innervation of the wrist with an emphasis on pathological and therapeutic aspects. The nerves involved in wrist innervation and their mechanoreceptor endings are described. The literature over the past 30 years includes several topics that are still subjects of discussion and debate and require further research.

Percutaneous Radiofrequency Ablation of the Posterior and Anterior Interosseous Nerves for Chronic Wrist Pain: A Novel Technique

The treatment of chronic wrist pain, due to posttraumatic, degenerative, or inflammatory arthritis, is challenging to adequately manage. The ideal surgical procedure should preserve wrist mobility and provide long-lasting pain relief. In this regard, denervation aims to decrease wrist pain by interrupting sensory innervation, without impairing motor function, and avoids the need for postoperative immobilization to decrease the risk of stiffness. For these reasons, denervation is particularly attractive as a possible treatment for chronic wrist pain. Our aim was to describe our novel technique for partial percutaneous wrist denervation, performed by radiofrequency ablation of the posterior and anterior interosseous nerves, and to report on the prospective outcomes over a 1-year follow-up for 3 patients (4 wrists) treated as of March 2019. The technique is performed on an outpatient basis and does not require postprocedure wrist immobilization or restriction in activities of daily living or work. Findings at the 1-year follow-up indicate that partial denervation improved grip strength, provided pain relief, maintained wrist motion, and improved subjective report of disabilities of the arm, shoulder, and hand. One patient did not report a benefit of the procedures, with other patients being very satisfied. Our percutaneous procedure is an evolution of the traditional partial denervation technique, providing advantages of being less invasive, not requiring restriction of movement or activities in the postoperative phase, can be performed on an out-patient basis, and does not preclude the subsequent use of invasive surgical procedures, as needed.

Long-Term Outcomes for Arthroscopic Thermal Treatment for Scapholunate Ligament Injuries

Background  Arthroscopic electrothermal treatment of low-grade Geissler's scapholunate interosseous ligament (SLIL) tears has shown clinical benefit at short-term follow-up. Questions/Purpose  This study aims to evaluate the long-term functional outcomes in patients undergoing this treatment. Patients and Methods  A retrospective review of all patients treated between 2005 and 2013 was performed. Patients were excluded with less than 5 years of follow-up, the presence of static SLIL injuries, prior wrist surgery, and concomitant denervation. Symptom resolution, return to activity, postoperative complications, range of motion, grip strength, and subsequent treatment were recorded. Each patient completed Quick Disabilities of the Arm, Shoulder, and Hand (QuickDASH), Modified Mayo Wrist (MMW), and Patient-Rated Wrist Evaluation (PRWE) questionnaires. Results  Nine patients underwent treatment for Geissler's grade I, II, and III SLIL injuries with a mean 7 years (range: 5-11 years) of follow-up. Mean grip strength was 99% of the nonsurgical extremity. Wrist motion was near symmetric with a mean of 76 (±14), 74 (±8), 21 (±13), and 40 degrees (±13) for wrist flexion, extension, radial deviation, and ulnar deviation. QuickDASH improved significantly by a mean 39 points (50 (preoperative)-11 [postoperative], p  = 0.009). Postoperative MMW and PRWE scores were 83 and 14, respectively. Visual analog scale (VAS) score was 1.4. A total of 90% was returned to their preinjury level of function or higher. Conclusions  Arthroscopic electrothermal treatment of low-grade Geissler's SLIL tears demonstrates excellent objective and subjective outcomes at a minimum 5-year follow-up, providing evidence that this is an effective, safe, and, most importantly, durable-therapeutic modality. Level of Evidence  This is a Level IV, case series study.

Lateral epicondylalgia: A primary nervous system disorder

Lateral epicondylalgia (LE) is the most common chronic painful condition affecting the elbow in the general population. Although major advances have been accomplished in recent years in the understanding of LE, the underlying physiopathology is still a reason for debate. Differences in clinical presentation and evolution of the symptoms among patients, suggest the need for revisiting the current knowledge about subjacent mechanisms that attempt to explain pain and functional loss. Previous models have suggested that the condition is mainly a degenerative tendinopathy, associated with changes in pain pathways and the motor system. The hypothesis of this work is that LE is the clinical manifestation of a primary nervous system disorder, characterized by an abnormal increase in neuronal activity and a subsequent loss of homeostasis, which secondarily affects the musculoskeletal tissues of the elbow-forearm-hand complex. A new model for LE is presented, supported by an in-deep analysis of basic sciences, epidemiological and clinical studies.

Scapholunate interosseous ligament dysfunction as a source of elbow pain syndromes: Possible mechanisms and implications for hand surgeons and therapists

Elbow pain syndromes are common upper extremity musculoskeletal disorders, and they are usually associated with repetitive occupational exposure. Ligaments are often one of the sources of musculoskeletal disorders because of their mechanical and neurological properties. The wrist ligaments are some of the ligaments most vulnerable to occupational exposure. Since most occupational tasks require wrist extension for handling tools and loading, the scapholunate interosseous ligament (SLIL) bears greater strain during loading, which results in creep deformation and hysteresis. Ligamentous creep may result in diminished ability to detect signal changes during joint movements, which impairs neuromuscular control established by ligamentomuscular reflex arcs elicited from mechanoreceptors in the ligaments. Changes in muscle activation patterns of forearm muscles due to diminished ligamentomuscular reflexes may initiate a positive feedback loop, leading to musculoskeletal pain syndromes. The relationship between elbow pain syndromes and SLIL injury will be presented through two hypotheses and relevant pain mechanisms: 1. Repetitive tasks may cause creep deformation of the SLIL, which then impairs ligamentomuscular reflexes, leading to elbow pain disorders. 2. Lateral epicondylalgia may increase the risk of SLIL injury through the compensation of the lower extensor carpi radialis muscle activity by higher extensor carpi ulnaris muscle activity, which may alter carpal kinematics, leading to SLIL degeneration over time. The differential diagnosis is usually complicated in musculoskeletal pain disorders. The failure of treatment methods is one of the issues of concern for many researchers. A key element in developing treatment strategies is to understand the source of the disorder and the nature of the injury. We proposed that the differential diagnosis include SLIL injuries when describing elbow pain syndromes, particularly, lateral epicondylalgia.

El papel de la propiocepción y el control neuromuscular en las inestabilidades del carpo

La congruencia articular, la integridad ligamentaria y la compresión de las superficies articulares ocasionada por la contracción muscular se han considerado históricamente los tres pilares básicos para la estabilidad del carpo. En los últimos años se ha propuesto un nuevo factor para explicar los mecanismos de estabilización carpiana, la propiocepción y el control neuromuscular. La propiocepción en la muñeca se origina en órganos sensoriales localizados en los ligamentos y cápsulas articulares (los mecanorreceptores). La estimulación de los mismos inicia un reflejo involuntario que provoca una respuesta muscular selectiva dirigida a proteger la zona de la muñeca donde se ha originado la señal aferente. En este trabajo de revisión se pretende dar a conocer el concepto de propiocepción y control neuromuscular, el papel que tienen en la estabilidad del carpo y las posibles aplicaciones en la práctica clínica.

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.

Ultrasonographic Differentiation of Lateral Elbow Pain

Lateral elbow pain is often attributed to degenerative or posttraumatic impairment of the common extensor tendon. Ultrasonography assesses the soft tissue structures of the lateral elbow, allowing the differentiation between various underlying processes, including angiofibroblastic degeneration, hyaline degeneration, and inflammation, and exclusion of other possible causes of pain such as posterior interosseous and lateral antebrachial nerve compression. Furthermore, the real-time imaging nature of ultrasonography enables the detection of impingement of the lateral synovial fold, degenerative changes in the elbow recess, and elbow posterolateral instability during dynamic maneuvers. Ultrasonography is widely accessible and well tolerated by patients, making it a perfect method for establishing an initial diagnosis and monitoring the healing process. This review describes the possible causes of lateral elbow pain and their ultrasonographic differentiation.

Effect of Electrothermal Treatment on Nerve Tissue Within the Triangular Fibrocartilage Complex, Scapholunate, and Lunotriquetral Interosseous Ligaments

PURPOSE

To evaluate the effect of thermal treatment on neural tissue in the triangular fibrocartilage complex (TFCC), scapholunate interosseous ligament (SLIL), and lunotriquetral interosseous ligament (LTIL).

METHODS

The intact TFCC, SLIL, and LTIL were harvested from cadaveric specimens and treated with a radiofrequency probe as would be performed intraoperatively. Slides were stained using a triple-stain technique for neurotrophin receptor p75, pan-neuronal marker protein gene product 9.5 (PGP 9.5), and 4',6-diamidino-2-phenylindole for neural identification. Five TFCC, 5 SLIL, and 4 LTIL specimens were imaged with fluorescence microscopy. Imaging software was used to measure fluorescence signals and compare thermally treated areas with adjacent untreated areas. A paired t test was used to compare treated versus untreated areas. P < .05 was considered significant.

RESULTS

For the TFCC, a mean of 94.9% ± 2.7% of PGP 9.5-positive neural tissue was ablated within a mean area of 11.7 ± 2.5 mm(2) (P = .02). For the SLIL treated from the radiocarpal surface, 97.4% ± 1.0% was ablated to a mean depth of 2.4 ± 0.3 mm from the surface and a mean horizontal spread of 3.4 ± 0.5 mm (P = .01). For the LTIL, 96.0% ± 1.5% was ablated to a mean depth of 1.7 ± 0.7 mm and a mean horizontal spread of 2.6 ± 1.0 mm (P = .02). Differences in the presence of neural tissue between treated areas and adjacent untreated areas were statistically significant for all specimens.

CONCLUSIONS

Our study confirms elimination of neuronal markers after thermal treatment of the TFCC, SLIL, and LTIL in cadaveric specimens. This effect penetrates below the surface to innervated collagen tissue that is left structurally intact after treatment.

CLINICAL RELEVANCE

Electrothermal treatment as commonly performed to treat symptomatic SLIL, LTIL, and TFCC tears eliminates neuronal tissue in treated areas and may function to relieve pain through a denervation effect.

Surgical Treatment of Upper Extremity Pain

If the patient with hand pain remains without significant relief and without recovery of function after appropriate pharmaceutical and physical modality treatments, it is appropriate to consider a surgical approach to the pain. Categories of pain amenable to a surgical approach are pain caused by nerve compression, pain caused by a neuroma, and joint pain of neural origin. Compressed nerve should be decompressed and depending on the intraoperative findings a neurolysis also should be performed. Painful neuroma must be resected to stop the pain generator. For a painful joint, the biomechanics of that joint must first be stable before denervation.

The role of proprioception and neuromuscular stability in carpal instabilities

Carpal stability has traditionally been defined as dependent on the articular congruity of joint surfaces, the static stability maintained by intact ligaments, and the dynamic stability caused by muscle contractions resulting in a compression of joint surfaces. In the past decade, a fourth factor in carpal stability has been proposed, involving the neuromuscular and proprioceptive control of joints. The proprioception of the wrist originates from afferent signals elicited by sensory end organs (mechanoreceptors) in ligaments and joint capsules that elicit spinal reflexes for immediate joint stability, as well as higher order neuromuscular influx to the cerebellum and sensorimotor cortices for planning and executing joint control. The aim of this review is to provide an understanding of the role of proprioception and neuromuscular control in carpal instabilities by delineating the sensory innervation and the neuromuscular control of the carpus, as well as descriptions of clinical applications of proprioception in carpal instabilities.

Mini dorsal incision to the triangular fibrocartilage complex: a new surgical approach

The purpose of this paper is to describe a mini dorsal approach to the triangular fibrocartilage complex (TFCC). We describe a mini incision approach which aims to preserve the structure and proprioception of the primary and secondary stabilisers of the wrist joint. This approach requires less dissection and provides adequate exposure to the distal aspect of the TFCC and allows visualisation of the distal radial ulna joint (DRUJ) with complete TFCC lesions.

Sensory innervation of the triangular fibrocartilage complex: a cadaveric study

PURPOSE

To describe the sensory innervation of the triangular fibrocartilage complex (TFCC) to understand the potential for selective denervation as an alternative treatment for recalcitrant pain from stable TFCC IA lesions after failed nonsurgical treatment.

METHODS

Eleven fresh cadaveric limbs were dissected with × 3.2 loupe magnification in a proximal to distal manner. The candidate nerves were the dorsal cutaneous branch of the ulnar nerve, volar sensory branch of the ulnar nerve, anterior interosseous nerve, posterior interosseous nerve, medial antebrachial cutaneous nerve, and palmar cutaneous branch of the median nerve. We identified neural continuity to the TFCC histologically with S-100 protein antibody staining.

RESULTS

In the 11 specimens, the TFCC was innervated by the dorsal cutaneous branch of the ulnar nerve (100%), medial antebrachial cutaneous nerve (91%), volar branch of the ulnar nerve (73%), anterior interosseous nerve (27%), posterior interosseous nerve (18%), and palmar branch of the median nerve (9%).

CONCLUSIONS

These results provide an initial step in planning an operative partial TFCC denervation for recalcitrant TFCC IA injuries that fail nonsurgical treatment and possibly also arthroscopic debridement.

CLINICAL RELEVANCE

Based on the results of this anatomic study, it is possible to create an algorithm for performing nerve blocks of the TFCC that would aid in planning a surgical denervation procedure.

Comparative analysis of inter- and intraligamentous distribution of sensory nerve endings in ankle ligaments: a cadaver study

BACKGROUND

The aim of this study was to analyze the inter-, intraligamentous, and side-related patterns of sensory nerve endings in ankle ligaments.

METHODS

A total of 140 ligaments from 10 cadaver feet were harvested. Lateral: calcaneofibular, anterior-, posterior talofibular; sinus tarsi: lateral- (IERL), intermediate-, medial-roots inferior extensor retinaculum, talocalcaneal oblique and canalis tarsi (CTL); medial: tibionavicular (TNL), tibiocalcaneal (TCL), superficial tibiotalar, anterior/posterior tibiotalar portions; syndesmosis: anterior tibiofibular. Following immunohistochemical staining, the innervation and vascularity was analyzed between ligaments of each anatomical complex, left/right feet, and within the 5 levels of each ligament.

RESULTS

Significantly more free nerve endings were seen in all ligaments as compared to Ruffini, Pacini, Golgi-like, and unclassifiable corpuscles (P ≤ .005). The IERL had significantly more free nerve endings and blood vessels than the CTL (P ≤ .001). No significant differences were seen in the side-related distribution, except for Ruffini endings in right TCL (P = .016) and unclassifiable corpuscles in left TNL (P = .008). The intraligamentous analysis in general revealed no significant differences in mechanoreceptor distribution.

CONCLUSIONS

The IERL at the entrance of the sinus tarsi contained more free nerve endings and blood vessels, as compared to the deeper situated CTL. Despite different biomechanical functions in the medial and lateral ligaments, the interligamentous distribution of sensory nerve endings was equal.

CLINICAL RELEVANCE

The intrinsic innervation patterns of the ankle ligaments provides an understanding of their innate healing capacities following injury as well as the proprioception properties in postoperative rehabilitation.

Radial tunnel syndrome

Radial tunnel syndrome is a pain syndrome resulting from compression of the posterior interosseous nerve at the proximal forearm. It has no specific radiologic or electrodiagnostic findings. Treatment should be started conservatively; if not successful, surgical treatment is indicated. The posterior interosseous nerve may be explored through dorsal or anterior approaches. All the potential sites of entrapment should be released, including complete release of the superficial head of the supinator muscle. Surgical treatment is generally successful, but patients who have associated lateral epicondylitis or those who are involved in workers' compensation claims have less successful outcomes.

Effect of partial wrist denervation on wrist kinesthesia: wrist denervation does not impair proprioception

PURPOSE

To evaluate the potential effect of partial wrist denervation on wrist kinesthesia, we hypothesized that anesthetizing the anterior interosseous nerve and the posterior interosseous nerve does not impair the kinesthesia.

METHODS

We performed a double-blinded, prospective, randomized study on 80 healthy volunteers (20-54 y old) to compare the ability to detect active and passive wrist movement in 2 conditions. The test group received an anesthetic block of the anterior and posterior interosseous nerves, and the control group subjects received an injection of saline. The kinesthesia of the 2 groups was then tested in 2 conditions by measuring the error in an active and passive wrist repositioning task. Results were analyzed using a repeated measures analysis of variance.

RESULTS

In both active and passive conditions, there was no difference in the repositioning errors between the test group and the control group.

CONCLUSIONS

Our results show that kinesthesia is not impaired by blocking the anterior and posterior interosseous nerves. These findings are consistent for both active and passive motion. The study gives strong evidence that partial denervation does not impair wrist kinesthesia. However, because only kinesthesia was studied, we cannot conclude that partial denervation is a totally safe procedure for all aspects of proprioception.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic I.

Nerve-sparing dorsal and volar approaches to the radiocarpal joint

Surgical approaches to the wrist joint have traditionally been focused on providing wide exposure to allow adequate access to the carpus. In light of recent investigations on the innervation and proprioception of the wrist joint, one should also take into consideration not to denervate the wrist capsule and ligaments. In this manuscript, we propose 2 surgical approaches to the dorsal and volar radiocarpal joint, intended to minimize damage to the innervation of the capsule while providing ample access to the wrist.

Proprioception of the wrist joint: a review of current concepts and possible implications on the rehabilitation of the wrist

STUDY DESIGN

Narrative review. Recent years have brought new research findings on the subject of wrist joint proprioception, which entails an understanding of the wrist as part of a sensorimotor system where afferent information from nerve endings in the wrist joint affects the neuromuscular control of the joint. An understanding of proprioception is also essential to adequately rehabilitate patients after wrist injuries. The aim of this narrative review was to give the reader a background of proprioception as it relates to neuromuscular control and joint stability, what is presently known in relation to the wrist joint and how these findings may be applied to the field of wrist rehabilitation.

LEVEL OF EVIDENCE

5.

Unusual compression neuropathies of the forearm, part I: radial nerve

Peripheral compression neuropathies are familiar to the hand surgeon. Although compression neuropathies of the forearm are far less common than those of the wrist (namely, carpal tunnel syndrome), for the patient suffering from one of these neuropathies, a missed diagnosis has far-reaching consequences. In this 2-part review (I: Radial Nerve; II: Median Nerve), several compression neuropathies of the forearm are examined. We will first discuss compression neuropathies affecting the radial nerve: (1) posterior interosseous nerve syndrome, (2) radial tunnel syndrome, and (3) superficial radial nerve compression (Wartenberg's syndrome).

Immunohistochemical analysis of wrist ligament innervation in relation to their structural composition

PURPOSE

To analyze ligament innervation and the structural composition of wrist ligaments to investigate the potential differences in sensory and biomechanical functions.

METHODS

The ligaments analyzed were the dorsal radiocarpal, dorsal intercarpal, scaphotriquetral, dorsal scapholunate interosseous, scaphotrapeziotrapezoid, radioscaphoid, scaphocapitate, radioscaphocapitate, long radiolunate, short radiolunate, ulnolunate, palmar lunotriquetral interosseous, triquetrocapitate, and triquetrohamate ligaments. The ligaments were harvested from 5 cadaveric, fresh-frozen specimens. By using the immunohistochemical markers p75, Protein Gene Product 9.5, and S-100 protein, the mechanoreceptors and nerve fibers could be identified.

RESULTS

The innervation pattern in the ligaments was found to vary distinctly, with a pronounced innervation in the dorsal wrist ligaments (dorsal radiocarpal, dorsal intercarpal, scaphotriquetral, dorsal scapholunate interosseous), an intermediate innervation in the volar triquetral ligaments (palmar lunotriquetral interosseous, triquetrocapitate, triquetrohamate), and only limited/occasional innervation in the remaining volar wrist ligaments. The innervation pattern also was reflected in the structural differences between the ligaments. When present, mechanoreceptors and nerve fibers were consistently found in the loose connective tissue in the outer region (epifascicular region) of the ligament. Hence, ligaments with abundant innervation had a large epifascicular region, as compared with the ligaments with limited innervation, which consisted mostly of densely packed collagen fibers.

CONCLUSIONS

The results of our study suggest that wrist ligaments vary with regard to sensory and biomechanical functions. Rather, based on the differences found in structural composition and innervation, wrist ligaments are regarded as either mechanically important ligaments or sensory important ligaments. The mechanically important ligaments are ligaments with densely packed collagen bundles and limited innervation. They are located primarily in the radial, force-bearing column of the wrist. The sensory important ligaments, by contrast, are richly innervated although less dense in connective tissue composition and are related to the triquetrum. The triquetrum and its ligamentous attachments are regarded as key elements in the generation of the proprioceptive information necessary for adequate neuromuscular wrist stabilization.