Ligamento-Muscular Reflex Patterns Following Stimulation of a Thumb Carpometacarpal Ligament: An Electromyographic Study

Periarticular Proprioception: Analyzing the Three-Dimensional Structure of Corpuscular Mechanosensors in the Dorsal Part of the Scapholunate Ligament

INTRODUCTION

Sensory nerve endings transmit mechanical stimuli into afferent neural signals and form the basis of proprioception, giving rise to the self-perception of dynamic stability of joints. We aimed to analyze the three-dimensional structure of periarticular corpuscular sensory nerve endings in a carpal ligament to enhance our understanding of their microstructure.

METHODS

Two dorsal parts of the scapholunate ligament were excised from two human cadaveric wrist specimens. Consecutive cryosections were stained with immunofluorescence markers protein S100B, neurotrophin receptor p75, protein gene product 9.5 (PGP 9.5), and 4',6-diamidino-2-phenylindole. Three-dimensional images of sensory nerve endings were obtained using confocal laser scanning microscopy, and subsequent analysis was performed using Imaris software.

RESULTS

Ruffini endings were characterized by a PGP 9.5-positive central axon, with a median diameter of 4.63 μm and a median of 25 cells. The p75-positive capsule had a range in thickness of 0.94 μm and 15.5 μm, consisting of single to three layers of lamellar cells. Ruffini endings were significantly smaller in volume than Pacini corpuscles or Golgi-like endings. The latter contained a median of three intracorpuscular structures. Ruffini endings and Golgi-like endings presented a similar structural composition of their capsule and subscapular space. The central axon of Pacini corpuscles was surrounded by S100-positive cells forming the inner core which was significantly smaller than the outer core, which was immunoreactive for p75 and PGP 9.5.

CONCLUSION

This study reports new data regarding the intricate outer and intracorpuscular three-dimensional morphology of periarticular sensory nerve endings, including the volume, number of cells, and structural composition. These results may form a basis to differ between normal and pathological morphological changes in periarticular sensory nerve endings in future studies.

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.

Complex motions embedded in a hand exercise regimen - effects on thumb function in participants with carpometacarpal osteoarthritis: A pilot study

Objective

The goal of this pilot study was to identify changes associated with completion of a unique six-week hand exercise program in persons with carpometacarpal osteoarthritis.

Methods

Twenty-four individuals, aged 55-80, with doctor-diagnosed carpometacarpal osteoarthritis participated in the study. Movement data from standard clinical motions and complex multi-planar motions were obtained using a motion capture system at three-time points: an initial visit, after two weeks of hand exercises, and after completion of the six-week exercise program.

Results

This exercise program produced trends of improvement in complex multi-planar motions. Specifically, joint angle changes were seen during opposition and the formation of an "okay sign" that was included as part of the exercise program.

Conclusion

Through the use of motion capture, changes were identified in thumb joint function after exercise. Specifically, motions associated with the more complex multi-planar tasks showed changes in individual joint contributions following the six-week exercise intervention. The results suggest that further exploration of this exercise program, particularly the inclusion of complex multi-planar tasks during osteoarthritis treatment and associated evaluations, should be considered in future clinical studies.

Arthroscopic Assisted Treatment of Combined Trapezium and Bennett Fracture-Dislocation

Trapezium fractures are unusual; however, they represent the third most frequent fracture of the carpal bones. As they usually follow a high-energy trauma, they are associated with distal radius, Bennett, or Rolando fractures in 80% of cases. Traditional treatment options include, closed reduction and percutaneous pinning, or open reduction and internal fixation. To minimize the additional surgical trauma, an arthroscopic technique has been developed for safe, minimally invasive management of complex injuries of the first carpo-metacarpal joint. Intra-articular dislocated fracture fragments are reduced under direct visualization and fixed through small incisions. Limiting additional surgical damage on the carpo-metacarpal joint ligaments, capsule, and other soft tissues around the fracture preserves the blood supply to fracture fragments and also the proprioceptive system, which is key for the dynamic stability of such a hypermobile joint. This report confirms that the procedure is feasible, and a complete functional recovery can be expected with reduced postoperative rehabilitation.

First Carpometacarpal Joint Denervation: A Systematic Review

PURPOSE

The first carpometacarpal (CMC) joint is a frequent location of osteoarthritis in the hand. The denervation of the first CMC joint has gained traction as a viable treatment for CMC arthritis. This study reviewed literature on CMC denervation for first CMC arthritis.

METHODS

A systematic review of papers and abstracts was conducted. The preferred reporting items for systematic reviews and meta-analyses guidelines were followed. Articles including the results of CMC denervation were included. We compiled data on patient demographics, preoperative testing, intraoperative technique, and postoperative outcomes. Anatomic literature was also reviewed to assess agreement on the innervation of the first CMC joint.

RESULTS

Six anatomic studies and 9 clinical studies were included in this systematic review. Pinch strength, grip strength, and Kapandji scores increased on average in patients. Pain relief was noted on average in patients in 5 studies that reported pain outcomes. In studies that reported postoperative complications, the most frequent complications were radial paresthesias, hypoesthesia dorsal and/or distal to the surgical site, and wound infection.

CONCLUSIONS

The innervation of the CMC joint is controversial. This is reflected in clinical practice, wherein varied surgical approaches are used. Carpometacarpal denervation shows promise as an option to treat patients with CMC arthritis without joint instability, but its results vary. Additional clinical studies with longer-term follow-up and control groups are necessary to better determine its longevity and efficacy.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic V.

Alteration of Ligamento-Muscular Reflex Patterns After Cutaneous and Periarticular Desensitization of the Basal Thumb Joint: An Electromyographic Study

PURPOSE

Stimulation of the dorsoradial ligament (DRL) of the first carpometacarpal joint (CMC-1) has shown a ligamento-muscular reflex pathway between the DRL and CMC-1 stabilizing muscles in healthy volunteers. However, it remains unclear how this ligamento-muscular reflex pattern is altered after anesthetizing sensory skin receptors and administering a further periarticular block around the CMC-1 joint, which may influence the dynamic aspects of joint stability.

METHODS

Ligamento-muscular reflexes were obtained from the extensor pollicis longus, abductor pollicis longus, abductor pollicis brevis, and the first dorsal interosseous muscles in 10 healthy participants after establishing superficial anesthesia of the skin around the CMC-1. The DRL was stimulated with a fine wire electrode while EMG activities were recorded during isometric tip, key, and palmar pinch. The measurements were repeated after an additional periarticular CMC-1 block using 5 ml of 1% lidocaine. Average EMG values were analyzed to compare the prestimulus and poststimulus activity.

RESULTS

Statistically significant changes in poststimulus EMG activity were observed in all 4 muscles and all 3 tested thumb positions. A markedly reduced activity in all 4 muscles was observed in the palmar position, followed by the tip and key pinch positions. Almost no reactions were observed in the first 20 ms poststimulus for all muscles in all positions.

CONCLUSIONS

Superficial skin anesthesia and an additional periarticular CMC-1 block anesthesia resulted in a reduced ligamento-muscular reflex pattern in all 4 muscles.

CLINICAL RELEVANCE

Ligamento-muscular reflexes play an important role in dynamic CMC-1 joint stability. The elimination of early reactions, those considered joint-protective reflexes, is a potential risk factor for developing osteoarthritis or injury because it results in an inability to adequately protect and stabilize the joint in sudden movements.

Carpometacarpal and metacarpophalangeal joint collapse is associated with increased pain but not functional impairment in persons with thumb carpometacarpal osteoarthritis

INTRODUCTION

Due to the complex shape of the carpometacarpal (CMC) joint, a fixed joint collapse deformity of the thumb CMC (CMC1) and metacarpophalangeal (MCP1) joint can present in advanced stages of CMC1 osteoarthritis (OA), resulting in adduction of the first metacarpal (MC1) and hyperextension of the MCP1.

PURPOSE OF THE STUDY

To determine whether joint collapse deformity is associated with worse pain and/or functional impairment.

STUDY DESIGN

Cross-sectional.

METHODS

This study used the baseline data from 140 patients enrolled in a longitudinal study of treatment for CMC1 OA. (efficacy of combined conservative therapies on clinical outcomes in patients with CMC1 OA). Joint collapse was determined at baseline using a pinch gauge. Pain was assessed on a visual analog scale (0-100) and function was assessed using the Functional Index for Hand Osteoarthritis questionnaire (0-30). Pain and function and the presence of joint collapse were entered in a univariate logistic regression. The final adjusted model for pain and joint collapse included age and sex. The final adjusted model for function and joint collapse included Kellgren Lawrence grade and grip strength.

RESULTS

About 20% of participants demonstrated joint collapse on the tip-pinch test. The presence of joint collapse was associated with increased pain in the unadjusted [P = .047, OR = 2.45, 95% CI (1.01, 5.910)] and adjusted model [P = .049, OR = 2.45, 95% CI (1.00, 5.98)].

CONCLUSION

CMC1 patients with joint collapse reported increased pain compared with those without joint collapse. Future studies should determine the relationship between thumb hypermobility and joint collapse and how to manage these conditions effectively.

Alterated ligamento-muscular reflex pattern after stimulation of the anterior talofibular ligament in functional ankle instability

PURPOSE

Ligamento-muscular reflex pattern following stimulation of the anterior talofibular ligament (ATFL) was examined.

METHODS

The peroneus longus (PL), the tibialis anterior (TA), and tibialis posterior (TP) muscles were investigated in sixteen patients with functional ankle instability (FAI) and 16 age- and gender-matched controls. The ATFL was stimulated with a fine wire electrode while electromyographic (EMG) activities were recorded during isometric foot contraction of 20% maximal force in plantarflexion, dorsiflexion, supination and pronation. The complete measurement was repeated after a peroneal block anesthesia.

RESULTS

Statistically significant changes in post-stimulus EMG activity were observed in all three muscles and all four tested foot positions. In supination, the PL showed no reactions in both groups before and after anesthesia. The post-stimulus inhibition of the TA seen after 80 and 180 ms disappeared in controls after anesthesia. The TP had similar inhibitory responses in both groups.

CONCLUSION

Ligamento-muscular reflex pattern is alterated in FAI. While early reactions are essential in protecting the ankle joint in sudden movements, the later responses indicate a supraspinal control of neuromuscular stability of the ankle joint. Proprioceptive rehabilitation of the PL, TA, and TP is crucial in FAI to compensate for post-traumatic ligamentomuscular reflex deficiencies.

LEVEL OF EVIDENCE

II.