Desensitizing the posterior interosseous nerve alters wrist proprioceptive reflexes

Immunohistochemical Investigation of Mechanoreceptors Within the Injured Scapholunate Ligament

PURPOSE

Scapholunate ligaments (SLLs) play a well-established role in maintaining carpal alignment and kinematics, and are innervated with sensory mechanoreceptors located within the ligaments. They are involved in the afferent arc of dynamic wrist stability. The aim of this study was to describe the changes in these mechanoreceptor populations in injured SLLs.

METHODS

Injured SLLs were collected from human wrists at the time of SLL reconstruction or limited wrist fusion, where the ligament remnants would otherwise be discarded. These specimens were formalin-fixed and paraffin-embedded for immunohistochemical analysis to identify mechanoreceptors, which were then classified by type and location within the ligament.

RESULTS

A total of 15 ligaments were collected, with the interval from injury ranging from 39 days-20 years. Eleven ligaments were collected less than one year after injury, and four ligaments were collected two years or more after injury. A total of 66 mechanoreceptors were identified, with 50 mechanoreceptors identified in nine of the 11 specimens collected less than one year after injury. In this group, 54% of the mechanoreceptors resided in the volar subunit, 20% in the dorsal subunit, and 26% in the proximal subunit. Two of the four specimens collected two years or later after injury contained mechanoreceptors, all of which were located in the dorsal subunit. Increasing time from injury demonstrated a decline in mechanoreceptor numbers within the volar subunit.

CONCLUSIONS

Mechanoreceptors were consistently located in the SLL, particularly in the volar subunit of specimens collected less than one year after injury.

CLINICAL RELEVANCE

Ligament reconstruction techniques aim to primarily reconstitute the biomechanical function of the disrupted SLL; however, re-establishing the afferent proprioceptive capacity of the SLL may be a secondary objective. This suggests the need to consider the reconstruction of its volar subunit particularly in those managed within one year of injury.

Rehabilitation of stage-one scapholunate instability (ReSOS): An online survey of UK practice

Introduction

Scapholunate instability is one of the most frequent types of wrist instability, but optimal management is not established. This research aims to identify current conservative management strategies for stage-one scapholunate instability and how these interventions are evaluated in the UK.

Methods

A cross-sectional online survey of UK physiotherapists and occupational therapists with self-reported experience in the rehabilitation of stage-one scapholunate instability (ReSOS), was developed using the CROSS guideline and a clinical vignette. The frequency of treatment strategies was collated via a five-point Likert-type scale and evaluation strategies via fixed-response answers at three-to-six, seven-to-eleven and after 12 weeks post-injury. Data were analysed descriptively.

Results

Forty-three electronic surveys were completed and analysed. Thirty physiotherapists and 13 occupational therapists responded, with 90% working in the NHS. Activity advice and education was the most frequently used treatment at all time-points (100%, 98%, 98%). Quick-DASH was most frequently used region-specific patient reported outcome measure at all time-points (72%, 60%, 67%).

Discussion

Despite some identified themes, including neuromuscular rehabilitation strategies, the supporting evidence is limited in the ReSOS. It is unclear what rehabilitation and evaluation strategies are optimal and the development of a consensus on best practice is recommended.

Denervation of the hand and wrist: A systematic review

With an aging population and the increasing prevalence of arthritic pathologies of the hand and wrist, denervation is one therapeutic option for hand surgeons. In case of pain but preserved motion, denervation is a treatment of choice. We conducted a systematic review of the literature, searching the MEDLINE, LILACS, SciELO and PubMed databases for cohorts reported in the last 20 years on denervation of the wrist and trapeziometacarpal, metacarpophalangeal and interphalangeal joints with a focus on postoperative outcomes, selecting 25 articles. The 1187 patients were divided into 3 groups: wrist denervation (999 patients), trapeziometacarpal denervation (124 patients), and metacarpophalangeal and interphalangeal denervation (64 patients). Improvements were found for pain (55.73%, 86%, 85%, respectively), range of motion (11.8%, 4°, 17°) and satisfaction (80.67%, 87.5%, 81.8%). Grip strength increased in wrist and trapeziometacarpal denervation (31.04% and 23%). The results suggest that denervation can be an alternative to arthroplasty or arthrodesis for painful wrist and hand joints, without precluding subsequent procedures if necessary.

The Relationship Between the Wrist Flexion Creases and the Volar Radiocarpal Joint: A Cadaveric Study

BACKGROUND

Surgical approaches to the volar radiocarpal joint have historically entailed wide exposure, possibly contributing to poor wound healing and wrist denervation. To avoid wound complications and wrist denervation, minimally invasive and percutaneous approaches to the volar radiocarpal joint have been proposed. To help guide these minimally invasive or percutaneous approaches to the joint, we sought to characterize the relationship between the volar wrist flexion creases and the volar radiocarpal joint. We propose that the wrist flexion creases will be a reliable method for localizing the joint.

METHODS

Ten cadaveric upper-extremity specimens consisting of fingertip to mid forearm were obtained. Measurements from the proximal and distal wrist flexion creases were taken via fluoroscopy and gross dissection.

RESULTS

The wrist flexion creases were located distal to the volar radiocarpal joint in all specimens. The volar radiocarpal joint was located 7 and 16 mm proximal to the proximal and distal wrist flexion creases, respectively. The radiographic anatomy correlated well with the underlying deep anatomy.

CONCLUSIONS

The wrist flexion creases can serve as a reliable superficial landmark for the identification of the volar radiocarpal joint. These landmarks aid clinicians in performing or interpreting a physical examination or in performing minimally invasive or percutaneous approaches to the volar radiocarpal joint.

Arthroscopic scapholunate ligament repair and dorsal capsulodesis with suture anchor in acute and subacute scapholunate dissociation

PURPOSE

The objective of this study was to investigate the potential of arthroscopic scapholunate ligament repair and dorsal capsulodesis with suture anchor as a treatment option for patients experiencing symptomatic acute and subacute (< 3 months) scapholunate instability.

METHODS

From Jan. 2017 to Jan 2020, 19 wrists with acute or subacute tears of the SL ligament with symptomatic instability were treated with arthroscopic SL repair and dorsal capsulodesis with a suture anchor. The average time from injury to operation was 8.8 weeks (range, 4-11 weeks) and the regular follow-up mean duration at our clinic was 26.5 months (range, 24-32 months). The pain score according to the visual analog scale, wrist range of motion, grip strength, radiographic outcomes and functional outcomes according to the Modified Mayo Wrist Score (MMWS) were evaluated preoperatively and postoperatively during the follow-up period.

RESULTS

All 19 patients had rupture and dissociation of the SL ligament in the radiocarpal joint. The total arc of wrist motion in the flexion-extension plane loss averaged 5.1° (P > .01).The Wilcoxon signed-rank test was used to compare the results: grip force improved significantly with 14.7% improvement of that on the normal side (P < .01); the postoperative MMWS was significantly better than the preoperative scores (P < .01). Of 19 patients of the series, 18 patients (94.7%) achieved good or excellent results according to the MMWS and 16 patients (84.2%) resumed their previous activities. Only one patient (5.3%) had residual laxity of the scapholunate ligament joint at 15 months of follow-up.

CONCLUSIONS

At a minimum of two years of follow-up, patients with acute or subacute symptomatic dissociation of scapholunate ligament instability who underwent arthroscopic scapholunate ligament repair and dorsal capsulodesis with suture anchor treatment had satisfactory results.

LEVEL OF EVIDENCE

Level IV, case series.

The effects of partial wrist denervation in wrist osteoarthritis: patient-reported outcomes and objective function

This prospective longitudinal study aimed to analyse the effect of partial wrist denervation on patient-reported outcomes, quality of life and objective function in symptomatic wrist osteoarthritis during the first year after surgery. Sixty consecutive patients underwent an anterior and posterior interosseous neurectomy during 2018-2020. Disabilities of the Arm, Shoulder and Hand, Patient-Rated Wrist Evaluation, EuroQol-5D-3L, pain at rest and on load, and objective function were assessed preoperatively and 3, 6 and 12 months postoperatively. Generalized estimating equations were used to analyse the effect on the outcome variables. Disabilities of the Arm, Shoulder and Hand, Patient-Rated Wrist Evaluation and pain scores improved significantly postoperatively with no decline over time, but no patient reported outcome measure reached the minimal clinically important difference. Quality of life, strength and range of motion did not improve. We found no complications. Seventeen patients needed further surgery during the study period. More studies are needed to evaluate whether denervation is truly effective or not.Level of evidence: II.

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.

Flow-Through Arterialized Posterior Interosseous Nerve Grafts for Digital Neurovascular Bundle Defects: Anatomical Study

BACKGROUND

Digital neurovascular bundle defects are often encountered during crush or avulsion injuries and require complex reconstruction. Use of an arterialized nerve graft (neurovascular graft) serving both as an interpositional arterial conduit and as a nerve graft could be a reconstructive option in these cases. In this anatomical study, the authors aimed to describe a neurovascular graft of the posterior interosseous nerve and a branch of the anterior interosseous artery for neurovascular bundle reconstruction of the fingers.

METHODS

Eighteen forearms were injected with red latex in order to collect the anatomical characteristics of the posterior interosseous nerve and the artery running near it.

RESULTS

In all cases, the posterior interosseous nerve was followed by a branch of the anterior interosseous artery: the distal dorsal branch of the anterior interosseous nerve. The origin of this artery was proximal to the radiocarpal joint, at an average of 56.5 ± 11.1 mm. The proximal and distal diameters of the branch of the anterior interosseous artery were 1.6 ± 0.2 and 1.1 ± 0.2 mm, respectively. The proximal and distal diameters of the posterior interosseous nerve were 1.2 ± 0.3 mm and 1.1 ± 0.3 mm, respectively.

CONCLUSIONS

These results show that a potential free neurovascular graft using the posterior interosseous nerve as nerve graft and the anterior interosseous artery as an arterial bypass to reconstruct both the nerve and arterial tree of the finger could be a useful approach. The authors speculate that this graft could be used to reconstruct the neurovascular bundle of amputated or devascularized digits.

Alterations in forearm muscle activation patterns after scapholunate interosseous ligament injury: A dynamic electromyography study

STUDY DESIGN

Case control.

PURPOSE OF THE STUDY

This study aimed to investigate the alterations seen in the activation patterns of the forearm muscles and to demonstrate the associated functional outcomes, in patients with scapholunate interosseous ligament (SLIL) injury.

METHODS

The study involved 15 patients with SLIL injury (instability group) and 11 healthy participants (control group). Both groups were evaluated with regard to their pain, grip strength, and upper extremity functional level (disabilities of the arm, shoulder and hand and patient-rated wrist evaluation questionnaires), and they also underwent a dynamic electromyography analysis of their forearm muscle activity. The activation patterns of the extensor carpi ulnaris (ECU), extensor carpi radialis (ECR), flexor carpi ulnaris, and flexor carpi radialis muscles during wrist extension and flexion were recorded by means of surface electromyography.

RESULTS

In the instability group, the pain severity was higher and the functional level was worse than in the control group (P < .05). Furthermore, during wrist extension, the ECR activity was lower and the ECU activity was higher in the instability group than in the control group (P < .05).

CONCLUSION

Dynamic stabilization of the wrist, flexor carpi ulnaris, and flexor carpi radialis muscles have been shown to play an active role with ECU and ECR. Increased ECU and decreased ECR activation may pose a potential risk in terms of enhancing the scapholunate gap. We, therefore, propose that appropriate preventive neuromuscular exercise strategies implemented as part of a physiotherapy program for patients with SLIL lesions might increase the contribution of the dynamic stability effect of the relevant muscles.

A New "Denervation" Technique for Painful Arthritic Wrist

Wrist denervation is, by the way, one of the most performed and long-lasting surgical technique for wrist arthritis. Despite many progresses in upper extremity joint arthroplasty, wrist arthritis remains difficult to treat specially in young patients and heavy manual workers. The aim of this technical article is to describe a new outpatient's procedure in which applying pulsed radio frequency on nerve structure of the wrist could achieve similar clinical results of a wrist denervation without surgical incision.

Effects of sense and functionality changes in the hands on activity and participation in patients with juvenile scleroderma

OBJECTIVES

The purpose of the study was to examine the effects of sense and functionality changes in the hands on activity and participation in patients with juvenile scleroderma (JS).

METHODS

Sixteen patients with juvenile localized scleroderma (JLS), 14 patients with Juvenile Systemic Sclerosis (JSS), and 30 healthy controls were included. Light touch-deep pressure sensation was assessed by Semmes-Weinstein monofilament test (SWMT). Localization sensation testing was performed by lightly stroking the patient's skin. The hand joint range of motion was measured with a goniometer, hand grip strength with Dynomometer, the pinch gripping force with pinch meter, and the hand mobility with modified Hand Mobility in Scleroderma (mHAMIS). Children completed their activity and participant performance status with 'Childhood Health Assessment Questionnaire (CHAQ)' and 'Jebson Taylor Hand Function Test (JTHFT)' questionnaire tests. The quality of life was evaluated using the 'Scleroderma Health Assessment Questionnaire (SHAQ)'.

RESULTS

There were significantly differences among evaluated three groups in light of touch-deep pressure sensation, sense of touch localization, range of motion, mHAMIS scores, JTHFT scores, all CHAQ scores, and almost all SHAQ score (p < .05). Over than half of patients with JSS (57.1%) and almost half of patients with JLS stated that their diseases obstructed them from doing any activity (p < .001). A significant percent of JSS patients (64.3%) had hand and wrist joint involvement.

CONCLUSION

Sensory and functional disorders caused by hand involvement in JS patients result in limitation of daily living activities and affect negatively the effective usage of the hand. Approximately half of the JS patients had disabilities in performing pinch motor skills of hands. The assessment of sensory symptoms that affect the functionality, activity level and participation of JSS and JLS patients should be considered during the routine clinical examination. We suggest the sensory therapies as an important factor in increasing the effectiveness of rehabilitation.

A Multicenter Matched Cohort Study of Processed Nerve Allograft and Conduit in Digital Nerve Reconstruction

PURPOSE

Biomaterials used to restore digital nerve continuity after injury associated with a defect may influence ultimate outcomes. An evaluation of matched cohorts undergoing digital nerve gap reconstruction was conducted to compare processed nerve allograft (PNA) and conduits. Based on scientific evidence and historical controls, we hypothesized that outcomes of PNA would be better than for conduit reconstruction.

METHODS

We identified matched cohorts based on patient characteristics, medical history, mechanism of injury, and time to repair for digital nerve injuries with gaps up to 25 mm. Data were stratified into 2 gap length groups: short gaps of 14 mm or less and long gaps of 15 to 25 mm. Meaningful sensory recovery was defined as a Medical Research Council scale of S3 or greater. Comparisons of meaningful recovery were made by repair method between and across the gap length groups.

RESULTS

Eight institutions contributed matched data sets for 110 subjects with 162 injuries. Outcomes data were available in 113 PNA and 49 conduit repairs. Meaningful recovery was reported in 61% of the conduit group, compared with 88% in the PNA group. In the group with a 14-mm or less gap, conduit and PNA outcomes were 67% and 92% meaningful recovery, respectively. In the 15- to 25-mm gap length group, conduit and PNA outcomes were 45% and 85% meaningful recovery, respectively. There were no reported adverse events in either treatment group.

CONCLUSIONS

Outcomes of digital nerve reconstruction in this study using PNA were consistent and significantly better than those of conduits across all groups. As gap lengths increased, the proportion of patients in the conduit group with meaningful recovery decreased. This study supports the use of PNA for nerve gap reconstruction in digital nerve reconstructions up to 25 mm.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic III.

Arthroscopic Reinsertion of Acute Injuries of the Scapholunate Ligament Technique and Results

Objective  To describe a technique for treating acute injuries of the scapholunate ligament (SLL) by performing an arthroscopic reinsertion of the SLL and dorsal capsulodesis and to present the results obtained. Methods  The study deals with an analytical, prospective clinical study that included 19 consecutive patients with acute injury of the SLL. The range of joint motion, grip strength, pain according to the visual analog scale, functional outcomes according to the Mayo Wrist Score (MWS), and the QuickDASH Score were studied preoperatively and 6 and 12 months postoperatively. The complications and necessary reinterventions were recorded. Results  Nineteen patients with acute injury of the SLL were studied; mean age was 44 ± 2 years, 74% males, 58% complete rupture, and 42% partial rupture, treated with the above-mentioned technique. Thirty-seven percent also had a distal radius fracture and there was one case of perilunate dislocation. Improvement in pain, grip strength, joint balance, and functionality was observed 6 and 12 months postoperatively, with 79% of the cases with good or excellent results Conclusion  The arthroscopic reinsertion and dorsal capsular reinforcement of the SLL, allow a reliable and stable primary repair of the dorsal aspect of the ligament in acute or subacute SL injuries where there is tissue that can potentially be repaired, thus achieving an anatomical repair similar to that obtained with open surgery, but without the complications and stiffness secondary to aggressive interventions on the soft tissues that are inherent to the open dorsal approach.

Evaluation of proprioception in denervated and healthy wrist joints

We recruited 25 patients after complete wrist denervation and 60 healthy adults to investigate conscious and unconscious proprioception of the wrist. Ipsi- and contralateral joint-position sense, force sense, and wrist reflexes were measured. The latter were triggered by a trapdoor, recording electromyographic signals from the extensor carpi radialis brevis, extensor carpi ulnaris, flexor carpi radialis, and flexor carpi ulnaris muscles. No significant differences were found for joint position sense, force sense, and wrist reflexes between both groups, except for reflex time of the flexor carpi ulnaris after denervation of the left wrist as compared with the left flexor carpi ulnaris in controls or in right operated wrists. At a mean follow-up of 32 months (range 8 to 133), we found no proprioceptive deficit of the conscious proprioceptive qualities of joint position sense, force sense, and the unconscious proprioceptive neuromuscular control of wrist reflex time for most muscles after complete wrist denervation. We conclude from this study that complete wrist denervation does not affect the proprioceptive senses of joint position, force sense, and reflex time of the wrist.

Similar effects of two different external supports on wrist joint position sense in healthy subjects: A randomized clinical trial

The hand is one of the most injured organs. Proprioceptive rehabilitation decreases the incidence of injury while using external supports can increase proprioception. The aim of this study was to investigate the effects of taping and elastic bandaging on wrist joint position sense (proprioception) in healthy individuals. Sixty-eight healthy students were included in our study and randomized into two groups. External supports were to apply to the dominant hand for 24hours in both groups. Joint position sense was evaluated with an angle reproduction test before applying the external support and 20 minutes after and then 24hours later with the external support and after removing it. There were significant improvements in joint position sense 20 minutes after applying the external support and 24hours later (P<0.05). Although a significant decrease in joint position sense was observed after removing the external support compared to while wearing it (P<0.05), there was a significant improvement in the joint position sense relative to the pre-study assessment (P<0.05). In between group comparisons, the only significant difference was observed 20 minutes after the external support was applied: the taping group had better results in joint flexion position sense than the bandaging group (P<0.05), but in the other assessments there were no significant differences between two groups (P>0.05). It was found that two different types of external support can improve the wrist joint's position sense in healthy subjects. These procedures can be used as a supplemental treatment in wrist rehabilitation.

Finger joint denervation in hand osteoarthritis: Indications, surgical techniques and outcomes. A systematic review of published cases

In cases of osteoarthritis with preserved motion, joint denervation can be an effective alternative to arthroplasty or arthrodesis to reduce joint-related pain. Although denervation is a standardized procedure for wrist osteoarthritis, it is used sparingly for finger joints. We conducted a systematic review to summarize reported cases of finger joint denervation in hand osteoarthritis with a specific focus on surgical procedures and postoperative outcomes. PubMed, Cochrane and Science Direct databases were searched from 1998 to 2019 and 13 relevant articles were selected. Three hundred and twenty-five denervations were conducted on 291 patients. Distal interphalangeal (DIP) joint denervation was performed through a dorsal approach; 83% of patients were satisfied with the surgery and complications occurred in 58%. Proximal interphalangeal (PIP) joint denervation was performed through a palmar approach; 90% of patients were satisfied with the surgery; complications were observed in 14%. Good results were observed in 95% of patients who underwent metacarpophalangeal (MCP) joint denervation; complications were observed in 26%; denervation was carried out with dorsal and palmar approaches in all cases. Denervation of the trapeziometacarpal (TMC) joint was achieved through the Wagner approach (61%), multiple incisions (26%), or dorsal approach (13%); satisfaction rate was 91%, with a 6% complication rate. Finger joint denervation in hand osteoarthritis is a simple and effective procedure, providing satisfactory pain relief. Good results are reported in all studies, especially for PIP and TMC joint denervation. Further investigations should be conducted on DIP and MCP joint denervation.

Innervation of the hip joint capsular complex: A systematic review of histological and immunohistochemical studies and their clinical implications for contemporary treatment strategies in total hip arthroplasty

The hip joint capsule contributes to the stability of the hip joint and lower extremity, yet this structure is incised and often removed during total hip arthroplasty (THA). Increasing incidence of osteoarthritis is accompanied by a dramatic rise in THAs over the last few decades. Consequently, to improve this treatment, THA with capsular repair has evolved. This partial restoration of physiological hip stability has resulted in a substantial reduction in post-operative dislocation rates compared to conventional THA without capsular repair. A further reason for the success of this procedure is thought to be the preservation of the innervation of the capsule. A systematic review of studies investigating the innervation of the hip joint capsular complex and pseudocapsule with histological techniques was performed, as this is not well established. The literature was sought from databases Amed, Embase and Medline via OVID, PubMed, ScienceDirect, Scopus and Web of Science; excluding articles without a histological component and those involving animals. A total of 21 articles on the topic were identified. The literature indicates two primary outcomes and potential clinical implications of the innervation of the capsule. Firstly, a role in the mechanics of the hip joint, as mechanoreceptors may be present in the capsule. However, the nomenclature used to describe the distribution of the innervation is inconsistent. Furthermore, the current literature is unable to reliably confirm the proprioceptive role of the capsule, as no immunohistochemical study to date has reported type I-III mechanoreceptors in the capsule. Secondly, the capsule may play a role in pain perception, as the density of innervation appears to be altered in painful individuals. Also, increasing age may indicate requirements for different strategies to surgically manage the hip capsule. However, this requires further study, as well as the role of innervation according to sex, specific pathology and other morphometric variables. Increased understanding may highlight the requirement for capsular repair following THA, how this technique may be developed and the contribution of the capsule to joint function and stability.

Buying Time: Long-Term Results of Wrist Denervation and Time to Repeat Surgery

Background: This study reviews long-term outcomes of partial wrist denervation focusing on need for and time to revision procedure. Methods: A retrospective study was conducted of all patients undergoing partial wrist denervation between 1994 and 2014. At average latest follow-up of 6.75 years (range, 1-21 years), clinical and radiographic data and need for revision surgery were recorded. Results: There were 100 wrists in 89 patients (61 male, 28 female) with average age at surgery of 54 years (range, 26-80). Principal diagnoses were arthritis (58%), inflammatory (19%), and posttraumatic arthritis (7%). Average flexion-extension arc was 83% and grip strength 75% of unaffected extremity. Average Mayo Wrist Scores improved from 48 preoperatively to 77 postoperatively. Sixty-nine percent of patients did not undergo other procedures during the time interval studied. Thirty-one percent underwent revision at an average of 26 months following denervation (range, 2-165). Conclusions: Partial wrist denervation is a motion-preserving procedure for patients with refractory wrist pain with 69% in this series requiring no further procedures. The remaining 31% experienced average symptom relief for 2 years prior to ultimately undergoing revision operation.

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

PURPOSE

The dorsoradial ligament (DRL) is essential for stability of the first carpometacarpal joint (CMC1) and is innervated with nerve endings and mechanoreceptors known to contribute to joint proprioception. The influence of these nerve endings on the neuromuscular stability of CMC1 is not yet known. This study investigated whether a ligamento-muscular reflex pathway is present between the DRL and CMC1 muscles.

METHODS

Ten healthy subjects (5 women and 5 men, mean age 28 years; range, 24-37 years) were included. Four primary CMC1 stabilizing muscles were investigated: the extensor pollicis longus, abductor pollicis longus (APL), abductor pollicis brevis, and first dorsal interosseous. Needle electrodes were inserted into each muscle and a fine-wire electrode was inserted into the DRL. The DRL was stimulated at 200 MHz while EMG activities in the muscles were recorded during isometric tip, key, and palmar pinch. Average EMG values were analyzed to compare prestimulus (t₁) with post-stimulus (t₂) activity.

RESULTS

Poststimulus changes were observed in all 4 muscles and 3 positions tested. During tip pinch we observed mass inhibition with a decrease in all muscle amplitudes. In key pinch we observed a rapid co-contraction response. Rapid inhibitory response of antagonistic musculature was observed during palmar pinch. The APL was the only muscle to react within 20 ms after stimulation.

CONCLUSIONS

We identified CMC1 ligamento-muscular reflexes. The mass inhibition of activity observed during tip pinch indicated a protective ligamento-muscular relation that affects all 4 muscles. The co-contractions observed promote joint stability. The fast response in the APL, coupled with its neuroanatomical proximity to the DRL, indicate a particular role in CMC1 proprioception.

CLINICAL RELEVANCE

Proper ligamentous support and retained innervation is likely important for adequate joint function; their innate functions ought to be considered when planning surgical or orthotic treatments.

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.

Arthroscopic-Assisted Partial Wrist Arthrodesis

Partial wrist arthrodesis (PWA) is a well-known procedure for treating degenerative or posttraumatic wrist conditions. Four-corner fusion (4CF) is mostly used for scapholunate advanced collapse and scaphoid nonunion advanced collapse. The author performed 39 procedures, including 4CFs, 2-corner fusions, 3-corner fusions, scaphoid-capitate/scaphoid-capitate-lunate fusions, scaphoid-trapezium-trapezoid arthrodeses, and radioscapholunate arthroscopic PWAs (A-PWAs). There were 8 revision cases including 4 partial nonunions. All A-PWAs healed satisfactorily after revision surgery. This article discusses the surgical techniques and tips to avoid mistakes. The pros and cons for open versus arthroscopic techniques and for screws versus Kirschner wires are also discussed.

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.

Denervation of the Wrist Joint for the Management of Chronic Pain

Wrist denervation for the management of chronic wrist pain is a safe and effective procedure that can delay or eliminate the need for more invasive and kinematically compromising salvage procedures. Wrist denervation has become increasingly popular since it was first described in 1959, and the technique has evolved from more extensive denervations to limited single-incision approaches. Many physicians have performed this procedure as a palliative approach to managing chronic wrist pain and as an adjunct to other procedures.

Arthroscopic Scapholunate Capsuloligamentous Repair: Suture With Dorsal Capsular Reinforcement for Scapholunate Ligament Lesion

Scapholunate ligament (SLL) injury is the most frequent injury of the intrinsic carpal ligaments. The dorsal part of the SLL is the most important part for the stability of the scapholunate joint, and tears of this part and at least one of its secondary capsular attachments cause scapholunate dissociation. The arthroscopic technique most frequently used for acute injuries is reduction and fixation with Kirschner wires, and techniques that involve a primary repair of the injured ligament are performed by open surgery with efficient results. However, they lead to significant stiffness of the wrist due to injury to the soft tissue caused by damage to the secondary dorsal stabilizers; the dorsal blood supply; and in many cases, the proprioceptive innervation of the posterior interosseous nerve. We present an all-arthroscopic technique for the direct repair of acute injuries of the dorsal part of the SLL using bone anchors, complemented by a dorsal arthroscopic plication that reconstructs the dorsal capsulo-scapholunate septum of the scapholunate complex.

Radical Wrist Denervation and Preliminary Results

Denervation is a well recognized procedure to treat degenerative or posttraumatic joint conditions, especially in cases where pain is a significant impediment to function even in the presence of stable and supple joint. However, this procedure currently is not as widely used for wrist surgeries as it merits. Denervation procedure obeys all-or-none phenomenon and we believe that even a few residual intact sensory fibers are able to transmit severe pain sensation and therefore every attempt should be made to target all the sensory supply to the wrist joint. In the present article a modified and radical technique using a single dorsal incision is proposed to address the hypothetical pitfalls of leaving undivided sensitive branches. Preliminary results of 21 cases operated on by this method are presented.

Multiplanar wrist joint proprioception: The effect of anesthetic blockade of the posterior interosseous nerve or skin envelope surrounding the joint

STUDY DESIGN

Randomized clinical trial.

PURPOSE

Contribution of the posterior interosseous nerve (PIN) and surrounding skin envelope to wrist proprioception is a topic of debate and the primary focus of this research.

METHODS

We performed a double-blinded, placebo control study in which subjects underwent baseline multiplanar testing of wrist proprioception. They were randomized to receive either anesthetic blockade of the PIN within the fourth dorsal compartment, or circumferential topical anesthetic blockade of skin surrounding the wrist. Corresponding opposite wrists underwent placebo intervention with saline injection or inert ultrasound gel. Subjects repeated proprioceptive testing.

RESULTS

Eighty subjects, 45 male and 35 female, mean age 33 years (range, 19-64 years), completed testing. The percentage of measurements falling outside a ±18° range did not differ between pre-treatment and post-treatment PIN blockade or for circumferential skin anesthesia.

CONCLUSIONS

Wrist proprioception appears to be a multifactorial phenomenon. Surgeons may sacrifice the PIN without concern for effect on joint proprioception.

LEVEL OF EVIDENCE

Level I.

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.

Arthroscopic ligamentoplasty of the dorsal and volar portions of the scapholunate ligament

Classical arthroscopic techniques for scapholunate instability consist of debridement, thermal shrinkage, and percutaneous pinning. Good results are obtained in acute lesions or in chronic partial tears, but they are less predictable when the lesion is complete, because of the poor healing capacity of the scapholunate ligament and because it is not possible to perform an anatomic ligamentous reconstruction with these techniques. Open techniques are thus required for reconstruction, but they damage the soft tissues. We recently published a description and cadaver study of an arthroscopic ligamentoplasty, trying to combine the advantages of arthroscopic techniques (minimally invasive surgery) and open techniques (reconstruction of the ligament). With this approach, it is possible to reconstruct the dorsal scapholunate ligament and the secondary stabilizers while causing minimal damage to the soft tissues and avoiding injury to the posterior interosseous nerve and detachment of the dorsal intercarpal ligament. The current report describes an additional step to this technique with which it is possible to reconstruct the volar portion of the scapholunate ligament. We also describe an early mobilization postoperative protocol that we believe is equally important.

Scapholunate instability: proprioception and neuromuscular control

From a kinetic point of view, the wrist is considered stable when it is capable of resisting load without suffering injury. Several prerequisites are necessary for the wrist to be kinetically stable: bone morphology, normal articulating surfaces, ligaments, the sensorimotor system, the muscles crossing the wrist, and all nerves connecting to ligaments and muscles. Failure of any one of these factors may result in carpal instability. The terms "scapholunate (SL) dissociation" and "SL instability" refer to one of the most frequent types of wrist instability, resulting from rupture or attenuation of the SL supporting ligaments. From a radiologic point of view, SL instability may be dynamic or static. Unlike static instabilities, which tend to be painful and dysfunctional, a good proportion of dynamic SL instabilities remain asymptomatic and stable for prolonged periods of time. Such a lack of symptoms suggests that a ligament rupture, in itself, is not enough for a joint to become unstable. Certainly, the process of achieving stability is multifactorial and involves normal joint surfaces, ligaments, muscles, and a complex network of neural connections linking all these elements. In this article, we will review the neuromuscular stabilization of the SL joint and the proprioceptive mechanisms that contribute to the dynamic carpal stabilization.

Innervation patterns of thumb trapeziometacarpal joint ligaments

PURPOSE

The human thumb trapeziometacarpal (TM) joint is a unique articulation that allows stability during pinch and grip and great degrees of mobility. Because the saddle-shaped articulating surfaces of the TM joint are inherently unstable, joint congruity depends on the action of restraining ligaments and periarticular muscles. From other joints, it is known that proprioceptive and neuromuscular joint stability depend on afferent information from nerve endings within ligaments. We hypothesize that the TM joint ligaments may similarly be innervated, indicating a possible proprioceptive function of the joint.

METHODS

We harvested 5 TM joint ligaments in entirety from 10 fresh-frozen cadaver hands with no or only minor signs of osteoarthritis and suture-marked them for proximal-distal orientation. The ligaments harvested were the dorsal radial, dorsal central, posterior oblique, ulnar collateral, and anterior oblique ligaments. After paraffin-sectioning, we stained the ligaments using a triple-antibody immunofluorescent technique and analyzed them using immunofluorescence microscopy.

RESULTS

Using the triple-stain technique, mechanoreceptors could be classified as Pacinian corpuscles, Ruffini endings, or Golgi-like endings. The 3 dorsal ligaments had significantly more nerve endings than the 2 volar ligaments. Most of the nerve endings were close to the bony attachments and significantly closer (P = .010) to the metacarpal insertion of each ligament. The anterior oblique ligament had little to no innervation in any of the specimens analyzed.

DISCUSSION

The TM joint ligaments had an abundance of nerve endings in the dorsal ligaments but little to no innervation in the anterior oblique ligament. The Ruffini ending was the predominant mechanoreceptor type, with a greater density in the mobile metacarpal portion of each ligament.

CLINICAL RELEVANCE

Presence of mechanoreceptors in the dorsal TM joint ligaments infers a proprioceptive function of these ligaments in addition to their biomechanical importance in TM joint stability.

Proximal row carpectomy with allograft scaffold interposition arthroplasty

The authors present a solution for motion preservation in severe wrist arthritis with intercarpal involvement. Acellular dermal allograft is used as an interposition arthroplasty in these situations, rather than local tissue flaps such as previously described. Proximal row carpectomy has been shown to be one of the most successful procedures to correct chronic destructive arthritis in the wrist, keeping useful motion. Traditionally, a contraindication for proximal row carpectomy includes an arthritis that invades the lunate-capitate joint. The authors describe a technique to extend the traditional indications by covering the eroded articular surfaces with dermal allograft scaffold.

WRIST DENERVATION IN ISOLATION: A PROSPECTIVE OUTCOME STUDY WITH PATIENT SELECTION BY WRIST BLOCKADE

Surgical wrist denervation involves division of the anterior and posterior interosseous nerves and articular branches of the superficial radial nerve. In this outcome study, 37 patients were individually assessed and deemed suitable for denervation surgery due to appreciable symptom resolution following a local anesthetic wrist block. At a mean of 18 months following denervation surgery, median activity pain scores had decreased by 60% (p < 0.001) from initial assessment levels, and more than three quarters (30/37) of patients reported continued improvement in their activity pain (p < 0.001). More than two thirds of patients had a satisfaction VAS of greater than 50, with less postoperative resting pain and a greater reduction in postoperative activity pain as the important predictors of patient satisfaction. Thirty-one out of the 37 patients had not represented to our department for revision wrist surgery by a mean of 10.3 years follow-up. We have found this procedure useful in ameliorating symptoms for some patients who would conventionally have required partial or total wrist fusions with greater residual functional limitation.

The scapholunate interosseous ligament afferent proprioceptive pathway: a human in vivo experimental study

PURPOSE

To examine the afferent pathways of the scapholunate interosseous ligament (SLIL)-generated stimuli and their contribution to the overall carpal proprioception.

METHODS

We examined 5 selected patients with preganglionic global root avulsion, confirmed by previous brachial plexus exploration, during the initial stage of carpal arthrodesis surgery. Despite their anesthetic-flail extremity, both the distal axon and the ganglionic cell were intact and able to transfer afferent stimuli. We placed electrodes subcutaneously over the adjacent areas of the ulnar, median, and radial nerves at the elbow region and performed an intraoperative neurophysiologic study. We studied the homologous sensory action potentials (SAPs) generated at the wrist in relaxation, flexion, extension, radial deviation, and ulnar deviation positions at each nerve and repeated them in 2 stages. The first took place with the SLIL intact and the second with the SLIL lacerated. The noise from the rest of the wrist elements was digitally eliminated.

RESULTS

After the SLIL laceration, SAP intensities recorded at the median nerve in every wrist position were reduced. The radial and ulnar nerves showed differences of lesser degrees between the recorded SAP intensities before and after the ligament sectioning in every carpal position, with only the radial nerve following a specific pattern. The SAP intensity recorded at the median nerve in every carpal motion after the SLIL laceration was similar to the SAP intensity at relaxation with the SLIL intact, whereas recordings of various intensities were present for the radial and ulnar nerves.

CONCLUSIONS

The SLIL generates proprioceptive stimuli at every wrist position. The main innervation of the whole SLIL derives from the anterior interosseous nerve; a partial contribution of the posterior interosseous nerve focused on the dorsal subregion of the ligament may also be present.