Understanding midcarpal instability

Surgical Techniques in Nontraumatic Midcarpal Instability: Evaluating the Dorsal Capsulodesis and 3-Ligament Tenodesis Technique

BACKGROUND

Surgical management of midcarpal instability (MCI), also referred to as carpal instability nondissociative, remains controversial because of limited evidence on different techniques. This study aimed to assess and compare differences in patient-reported pain, hand and wrist function, satisfaction, range of motion, and return to work in patients with nontraumatic MCI who underwent surgical treatment either through dorsal wrist capsulodesis or 3-ligament tenodesis (3LT).

METHODS

Patients with MCI and persisting complaints after conservative therapy treated with 3LT or dorsal capsulodesis were included. Patients with posttraumatic instability were excluded. Primary endpoints included the Patient Rated Wrist Evaluation and Satisfaction with Treatment Result Questionnaire at 12 months postoperatively. All data were analyzed retrospectively.

RESULTS

A total of 91 patients treated with dorsal capsulodesis and 21 treated with 3LT between December of 2011 and December of 2019 were included. At 12 months postoperatively, both treatment groups reported significant improvements in pain and function scores. However, at 3 months postoperatively, the dorsal capsulodesis group exhibited significantly better outcomes, followed by a greater return-to-work rate (72%) compared with the 3LT group (50%). However, the capsulodesis group demonstrated a decreased range of motion at 3 months that was restored at 12 months postoperatively. No significant difference in satisfaction with treatment was observed.

CONCLUSIONS

Both 3LT and dorsal capsulodesis demonstrate promising results for addressing nontraumatic MCI. However, considering the quicker recovery and faster return to work associated with dorsal capsulodesis, the authors recommend favoring capsulodesis over 3LT when both surgical options are deemed suitable for the patient.

Articular Fragment Escape and Carpal Subluxation Following Distal Radius Fracture Fixation

Surgical fixation of distal radius fractures is among the more common procedures performed by hand surgeons. The approach to surgical management is based on a variety of factors including injury mechanism, fracture pattern, patient characteristics, bone quality, soft tissue injury, and surgeon preference. For the majority of fracture types, volar locking plate fixation has become the most commonly used method of fracture fixation. Although uncommon, complications can arise following this form of treatment, one of which is escape of an articular fragment with resultant carpal instability. More often seen in conjunction with poorly reduced or captured displaced volar lunate facet fragments, fixation failure and carpal instability can occur with other fracture patterns that have garnered less attention, particularly those involving the radial column or dorsal lunate facet. Thorough preoperative planning to recognize fracture patterns that lead to this complication is paramount. Proper selection of implants used to secure the fracture and the choice as well as duration of postoperative immobilization is critical to minimizing this complication. We aim to (1) describe the relevant anatomy involved with this complication, (2) organize and classify the various distal radius articular fragment escape patterns that can occur following fracture fixation, and (3) discuss strategies that can help prevent this complication.

Outcomes of an exercise program in patients with dorsal or volar midcarpal laxity: a cohort study of 213 patients

PURPOSE

Describing the outcomes of an exercise program on wrist and hand function for patients with midcarpal instability (MCI).

MATERIALS AND METHODS

This study has a prospective cohort design. Two hundred and thirteen patients with MCI were included. The intervention was a 3-month exercise program consisting of hand therapy and home exercises. The primary outcome was perceived wrist and hand function evaluated with the Patient-Rated Wrist/Hand Evaluation (PRWHE) three months after treatment onset. Secondary outcomes were conversion to surgery, pain, and satisfaction with treatment results.

RESULTS

PRWHE total scores improved from 51 ± 19 (mean ± SD) to 33 ± 24 at 3 months (95% CI: 36-30, p < 0.001). All visual analog scales for pain demonstrated clinically relevant improvements at 6 weeks and 3 months (p < 0.001). At 3 months, 81% of the participants would undergo the treatment again. After a median follow-up of 2.8 years, 46 patients (22%) converted to surgery.

CONCLUSIONS

We found clinically relevant improvements in hand and wrist function and pain. Most participants would undergo treatment again and 78% of the participants did not convert to surgery. Hence, non-invasive treatment should be the primary treatment choice for patients with MCI.

An anatomic study of the morphologic characteristics of the dorsal capitolunate ligament

PURPOSE

There is consensus in favor of a description of the dorsal ligaments of the carpus as not including a direct ligament between the lunate and capitate. On the other hand, there is an anatomical formation which, according to the currently accepted description, corresponds to the dorsal midcarpal capsule, itself thickened by the dorsal intercarpal ligament. The question is whether the capsule at this point deserves to be called an individualizable ligament. In our operative experience of the dorsal carpus, we have encountered a stout structure adherent to the lunate and capitate. In this article, we present the anatomic evidence of this structure's existence.

METHODS

Seven adult fresh frozen upper extremities were dissected. Three wrists were longitudinally sectioned in line with the middle finger metacarpal. The remaining 4 were dissected dorsally. Two representative samples of the stout structure connecting the lunate to the capitate were sent to pathology for histologic analysis and staining.

RESULTS

In all 3 of the longitudinally sectioned wrists, a thick band of tissue could clearly be seen, originating on the lunate, spanning the dorsal interval between the lunate and the capitate, and inserting on the capitate. With this structure intact, dorsal dislocation of the capitate was not possible, but preliminary sectioning of the structure allowed dislocation. In the 4 dorsally dissected wrists, the same connection was observed, palmar to the dorsal intercarpal ligament, in every specimen. The average dimensions of the dorsal capitolunate were: 15.25 ± 1 mm long, 8.75 ± 1 mm wide at the midpoint, and 1.75 ± 1 mm thick. The two specimens sent to pathology after sectioning showed longitudinally oriented collagen fibers. This structure also stained positive for elastin and contained intrasubstance vascular structures.

CONCLUSION

There is a stout ligamentous structure connecting the lunate to the capitate, palmar to the dorsal intercarpal ligament. Disruption of this structure appears to be necessary for dorsal dislocation of the capitate. Clinical studies are needed to gain better understanding of the exact function and importance of this structure.

Arthroscopic suture in the management of palmar midcarpal instability

Aims

Patients with midcarpal instability are difficult to manage. It is a rare condition, and few studies have reported the outcomes of surgical treatment. No prospective or retrospective study has reported the results of arthroscopic palmar capsuloligamentous suturing. Our aim was to report the results of a prospective study of arthroscopic suture of this ligament complex in patients with midcarpal instability.

Methods

This prospective single-centre study was undertaken between March 2012 and May 2022. The primary outcome was to evaluate the functional outcomes of arthroscopic palmar midcarpal suture. The study included 12 patients, eight male and four female, with a mean age of 27.5 years (19 to 42). They were reviewed at three months, six months, and one year postoperatively.

Results

There was a significant improvement in flexion, extension, grip strength, abbreviated version of the Disabilities of the Arm, Shoulder and Hand questionnaire score, and pain, in all patients. After telephone contact with all patients in March 2023, at a mean follow-up of 3.85 years (2.2 to 6.25), no patient had a persistent or recurrent clunk.

Conclusion

Arthroscopic suture of the midcarpal capsuloligamentous complex represents a minimally invasive, easy, and reproducible technique for the management of patients with midcarpal instbility, with a clear improvement in function outcomes and no complications.

Palmar midcarpal instability a narrative review of the literature: Have we reached a consensus on a treatment?

Palmar midcarpal instability (PMCI) is a wrist condition that requires treatment through non-surgical rehabilitation programs or surgical stabilization. This condition's natural history is poorly understood, and the optimal treatment approach remains unknown. Non-surgical treatments are initially implemented, followed by surgical stabilization if necessary. Arthrodesis and soft tissue stabilization are the two main surgical options for PMCI, with no established gold standard for treatment. A systematic review of 12 articles comparing arthrodesis and soft tissue stabilization was conducted to identify the optimal treatment approach for PMCI. Arthrodesis techniques, such as lunotriquetral arthrodesis, showed high functional outcomes but also high reintervention rates due to nonunion. Soft tissue stabilization techniques showed superior functional outcomes with less mobility loss and lower reintervention rates compared to arthrodesis. However, more studies are required to determine the optimal soft tissue technique. Based on this review we created a treatment algorithm for PMCI starting with non-surgical treatment first, followed by surgical stabilization if needed. Soft tissue stabilization techniques are preferred over arthrodesis due to better functional outcomes and lower reintervention rates. However, each patient's treatment approach should be individualized and evaluated independently to determine the best course of action. PMCI is a rare wrist condition, and further research is needed to better understand its natural history and establish a gold standard for treatment. The lack of literature comparing the two surgical options underscores the need for further research to determine the optimal treatment approach. Nonetheless, the current evidence suggests that soft tissue stabilization is a promising alternative to arthrodesis, providing superior functional outcomes and lower reintervention rates.

Midcarpal Instability

Midcarpal instability (MCI) of the wrist represents multiple distinct clinical entities that all have in common abnormal force transmission across the midcarpal joint. This can be asymptomatic but can also result in painful wrist motion, a characteristic catch-up clunk, and symptoms of instability. The carpus is stabilized by numerous extrinsic and intrinsic ligaments. Dynamic joint reactive forces between the proximal and distal carpal rows help create reciprocal motion, which results in smooth, physiologic wrist mechanics. Diagnosis of MCI requires a thorough history, physical examination, and adequate imaging. MCI can be managed nonsurgically with activity modification, physical therapy, specialized orthotics, medications, and corticosteroid injections. A variety of surgical treatment options exists to treat symptomatic MCI. These include arthroscopic thermal capsulorrhaphy, ligament repair or reconstruction, radial osteotomies, and limited radiocarpal or intercarpal fusions. Capsulorrhaphy or ligament repair is favored for mild to moderate cases; osteotomies can be used for the correction of bony deformities contributing to instability, whereas partial wrist arthrodesis is indicated for severe or recurrent instability and fixed deformities.

Midcarpal Instability: A Historical and Etymological Review

Although midcarpal instability was first described almost 45 years ago, this uncommon condition is still poorly understood by most clinicians today. Adding to the confusion, it is known by 2 different names: midcarpal instability and carpal instability nondissociative. In this article, we describe the history of the recognition of instability of the midcarpal joint, including its pathomechanics, classification, and treatment. We hope that a more complete understanding of the etymology and kinematics of the disorder will facilitate its future recognition and assist in appropriate treatment decision making.

Trapeziectomy for basal thumb osteoarthritis does not increase the risk of developing wrist osteoarthritis in the long term

BACKGROUND

Symptomatic osteoarthritis of the basal joint of the thumb (trapeziometacarpal joint) is a common disabling condition mainly affecting women. It is frequently treated with complete removal of the trapezium with or without soft-tissue interposition. There is limited evidence about whether removal of the trapezium affects stability of the wrist joint and increases the risk of developing wrist osteoarthritis. The aim of this study was to evaluate the long-term prevalence of OA in wrists with previous trapeziectomy compared to wrists with intact trapezium.

METHODS

Patients treated with surgery for trapeziometacarpal osteoarthritis at one orthopedic department were invited 10-29 (mean 17) years postoperatively for bilateral radiographic examination. We included radiographs from 114 hands with trapeziectomy and 46 hands with intact trapezium; 38 patients had unilateral trapeziectomy and intact contralateral trapezium. The radiographs were blinded so that the intact trapezium or the trapezial space after trapeziectomy was not visible. The radiographs were then evaluated for radiocarpal/midcarpal osteoarthritis independently by two assessors using three different osteoarthritis grading systems, including the Kellgren-Lawrence classification. The patients rated their satisfaction with the function of each of their hands on a visual analog scale (VAS) from 0 to 100 (higher score better).

RESULTS

The prevalence of osteoarthritis ranged from 20 to 26%, mostly mild (Kellgren-Lawrence grade 1). The prevalence of osteoarthritis did not differ between wrists with previous trapeziectomy and those with intact trapezium, both in the whole cohort and in the subgroup of patients with unilateral trapeziectomy and intact contralateral trapezium. There was no significant difference in hand function VAS scores between hands with previous trapeziectomy and hands with intact trapezium in the whole cohort or in the subgroup.

CONCLUSIONS

Removal of the trapezium as treatment for basal thumb osteoarthritis does not increase the risk of developing wrist osteoarthritis in the long term.

SMoC-Wrist: a sensorimotor control-based exercise program for patients with chronic wrist pain

STUDY DESIGN

This is a narrative review.

INTRODUCTION

Chronic wrist pain is a common disorder that can lead to considerable disability in performing activities in daily living and at work. Patients with nonspecific chronic wrist pain are regularly referred to a physiotherapist/hand therapist. Immobilization, avoiding excessive wrist load, steroid injections, and various physical therapy methods predominantly focus on the pain itself. However, these methods often do not result in a satisfactory long-term pain relief.

PURPOSE OF THE STUDY

In this article, we will describe the principles behind and content of a sensorimotor control-based exercise program as introduced by Videler et al., modified and substantiated by current insights into sensorimotor control training and wrist kinetics.

METHODS

Both structure and content of the modified exercise program (SMoC-wrist) are substantiated by recent scientific literature.

RESULTS

A clear 4-level exercise model based on sensorimotor principles is presented, that is, proprioceptive level, conscious static/isometric level, conscious dynamic level, and unconscious dynamic level. The content of each level and the transition toward the next level are described in detail.

DISCUSSION

Besides the substantiation of the exercise program, possible outcome measures for joint position sense and kinesthesia of the wrist are discussed.

CONCLUSION

We modified and substantiated a widely used exercise program for patients with nonspecific chronic wrist pain based on recent insights into sensorimotor control principles and wrist kinematics. The presented exercise program (SMoC-wrist) is not primarily focused on reducing pain but on functional reeducation and strengthening of the neuromusculoskeletal system on the basis of sensorimotor control principles.

Extrinsic and Intrinsic Ligaments of the Wrist

Carpal stability depends on the integrity of both intra-articular and intracapsular carpal ligaments. In this review, the role of the radial-sided and ulnar-sided extrinsic and intrinsic ligaments is described, as well as their advanced imaging using magnetic resonance arthrography (MRA) and contrast-enhanced magnetic resonance imaging (MRI) with three-dimensional (3D) scapholunate complex sequences and thin slices. In the last decade, the new concept of a so-called "scapholunate complex" has emerged among hand surgeons, just as the triangular ligament became known as the triangular fibrocartilage complex (TFCC).The scapholunate ligament complex comprises the intrinsic scapholunate (SL), the extrinsic palmar radiocarpal: radioscaphocapitate (RSC), long radiolunate (LRL), short radiolunate (SRL) ligaments, the extrinsic dorsal radiocarpal (DRC) ligament, the dorsal intercarpal (DIC) ligament, as well as the dorsal capsular scapholunate septum (DCSS), a more recently described anatomical structure, and the intrinsic palmar midcarpal scaphotrapeziotrapezoid (STT) ligament complex. The scapholunate (SL) ligament complex is one of the most involved in wrist injuries. Its stability depends on primary (SL ligament) and secondary (RSC, DRC, DIC, STT ligaments) stabilizers.The gold standard for carpal ligament assessment is still diagnostic arthroscopy for many hand surgeons. To avoid surgery as a diagnostic procedure, advanced MRI is needed to detect associated lesions (sprains, midsubstance tears, avulsions and chronic fibrous infiltrations) of the extrinsic, midcarpal and intrinsic wrist ligaments, which are demonstrated in this article using 3D and two-dimensional sequences with thin slices (0.4 and 2 mm thick, respectively).

Posttraumatic Carpal Instability Nondissociative

Background  Posttraumatic midcarpal instability nondissociative (CIND) is an exceptional rare condition, therefore the outcome after different treatment options remains unknown. Questions  The purpose of this study was to investigate the different treatment options for posttraumatic CIND. We also describe the different radiological and magnetic resonance imaging (MRI) findings in this patient cohort. Patients and Methods  We present outcomes of 10 patients who developed CIND following acute wrist trauma between 2007 and 2018, 3 with dorsal intercalated segment instability pattern (CIND-DISI) and 7 with volar intercalated segment instability (CIND-VISI) radiographically. Results  Three patients with CIND-VISI had satisfactory outcomes with conservative treatment. Two patients with irreducible CIND-DISI and one with CIND-VISI underwent proximal row carpectomy (PRC), two with reducible CIND-VISI had radiolunate fusion, and two with secondary osteoarthritis had total wrist fusion. All patients with CIND-DISI needed surgery, whereas only four of the seven patients with CIND-VISI needed surgery. On MRI, all three patients with CIND-DISI had rupture of the radiolunate ligament. Conclusions  The data collected in this study may provide the first step toward better understanding of the pathology for this exceptionally rare finding. In CIND-VISI, we have not seen any ligament injury in four patients. Therefore, conservative therapy is more likely to be the first step. In CIND-DISI, we recommend an operative procedure: if detected early, with ligament suture, otherwise by radiolunate fusion, PRC, or total wrist fusion. Level of Evidence  This is a Level IV study.

Carpal Instability: I. Pathoanatomy

The pathoanatomy of carpal instability is multifactorial and usually complex. A thorough medical history and clinical examination are essential, as well as profound knowledge of the specific instability patterns. The stability of the wrist is ensured by the carpal joint surfaces, by intact intra-articular (particularly the scapholunate interosseous ligament) and intracapsular ligaments, and by crossing extensor and flexor tendons, the latter making the proximal carpal row an "intercalated segment." An important classification feature is the distinction between dissociative and nondissociative forms of carpal instability. Among others, scapholunate dissociation, lunotriquetral dissociation, midcarpal instability, and ulnar translocation are the most common entities. Early forms of instability are considered dynamic. In the natural course, static instability of the wrist and osteoarthritis will develop. This review focuses on the pathoanatomical fundamentals of the various forms of carpal instability.

Demystifying Palmar Midcarpal Instability

Palmar midcarpal instability is an uncommon condition diagnosed clinically with a painful pathognomonic clunk on terminal ulnar deviation of the wrist. Various causes have been described, but congenital laxity of the carpal ligaments is thought to be a key contributor. Treatment commences with conservative measures. This includes proprioceptive training based on more recent concepts on the sensorimotor function of the wrist. When these measures plateau, surgery is considered. The lack of high-level evidence and consensus on its cause continue to hamper our understanding and knowledge of this condition. The purpose of this review is to examine the current evidence to conceptualize this mysterious, yet infrequent phenomenon, and to provide an algorithm on its management.

Biomechanical Effects of Radioscapholunate Fusion With Distal Scaphoidectomy and Triquetrum Excision on Dart-Throwing and Wrist Circumduction Motions

PURPOSE

Distal scaphoid and triquetrum excisions can improve the range of wrist motion after radioscapholunate (RSL) fusion, but little is known about the kinematics of dart-throwing and global circumduction motions. We hypothesized that these excisions could increase the range of motion without causing midcarpal instability.

METHODS

Seven fresh-frozen cadaver upper extremities were mounted on a testing apparatus after isolation and preloading of the tendons of the flexor carpi radialis, flexor carpi ulnaris, extensor carpi radialis, and extensor carpi ulnaris. Sequential loadings of the flexor carpi ulnaris and extensor carpi radialis simulated active dart-throwing motion. Passive circumferential loading produced the wrist circumduction motion. We measured the range of wrist motions with an electromagnetic tracking system in 4 experiments: intact, simulated RSL fusion, RSL fusion with distal scaphoid excision, and RSL fusion with distal scaphoid and total triquetrum excisions. To evaluate midcarpal stability, we conducted passive mobility testing of the distal carpal row in the radial, volar, ulnar, and dorsal directions.

RESULTS

Radioscapholunate fusion decreased the dart-throwing motion to a mean of 46% of the baseline value; distal scaphoid and triquetrum excisions increased the mean arc to 50% and 62%, respectively. Radioscapholunate fusion diminished the wrist circumduction to a mean of 43% of the baseline value, which increased to a mean of 58% and 74% after distal scaphoid and triquetrum excision, respectively. A significant increase in radial deviation was noted after distal scaphoid excision, and subsequent triquetrum excision significantly increased motion in the ulnar-palmar direction. Regarding midcarpal stability, dorsal translation significantly increased after distal scaphoid and triquetrum excisions.

CONCLUSIONS

Distal scaphoid and triquetrum excision after RSL fusion improved both dart-throwing and circumduction motions, but dorsal midcarpal instability occurred.

CLINICAL RELEVANCE

Subsequent carpal excisions may improve short-term outcome by increasing motions in a RSL-fused wrist; however, a potential risk of midcarpal instability should be considered.

Dynamic MRI of the wrist in less than 20 seconds: normal midcarpal motion and reader reliability

OBJECTIVE

To describe the normal motion pattern at the midcarpal compartment during active radial-ulnar deviation of the wrist using dynamic MRI, and to determine the observer performance for measurements obtained in asymptomatic volunteers.

METHODS

Dynamic MRI of 35 wrists in 19 asymptomatic volunteers (age mean 30.4 years, SD 8.6) was performed during active radial-ulnar deviation using a fast gradient-echo pulse sequence with 315 ms temporal resolution (acquisition time, 19 s). Two independent readers measured the transverse translation of the trapezium at the scaphotrapezium joint (STJ) and the capitate-to-triquetrum distance (CTD). Relationships between these measurements and laterality, sex, lunate type, and wrist kinematic pattern were evaluated.

RESULTS

At the STJ, the trapezium moved most in radial deviation, with an overall translation of 2.3 mm between ulnar and radial deviation. Mean CTD measurements were the greatest in ulnar deviation and varied 2.4 mm between ulnar and radial deviation. Mean CTD was greater in men than women in the neutral position (p = 0.019), and in wrists with type II lunate morphology during radial and ulnar deviation (p = 0.001, p = 0.014). There were no significant differences in trapezium translation or CTD with wrist laterality and kinematic pattern. Intraobserver and interobserver correlation coefficients were 0.97 and 0.87 for trapezium translation and 0.84 and 0.67 for CTD.

CONCLUSION

This study is the first to demonstrate the performance of dynamic MRI to quantify STJ motion and CTD. Dynamic MRI with a short acquisition time may be used as a tool to supplement static MRI in evaluation of the midcarpal compartment.

Management of Nondissociative Instability of the Wrist

Nondissociative carpal instability is instability of an entire carpal row and can lead to vague ulnar-sided wrist pain as well as a clunking wrist. The etiology of this process is most often generalized ligamentous laxity; however, it can infrequently occur as a result of trauma or malalignment of the radiocarpal joint. Whereas treatment remains controversial, the literature supports nonsurgical management and includes patient education, dynamic placement of orthoses, proprioceptive therapy, and extensor carpi ulnaris strengthening. If extensive nonsurgical therapy fails, surgical intervention includes soft tissue and bony procedures, all with high complication and failure rates and limited long-term outcome data.

Arthroscopic Distal Scaphoid Resection for Isolated Scaphotrapeziotrapezoid Osteoarthritis

PURPOSE

To investigate the radiographic and clinical results of arthroscopic distal scaphoid resection for isolated scaphotrapeziotrapezoid (STT) osteoarthritis and analyze the radiographic parameters associated with the functional outcomes.

METHODS

From 2008 to 2014, 17 wrists with symptomatic isolated STT osteoarthritis without carpal deformity underwent arthroscopic distal scaphoid resection. We evaluated visual analog scale (VAS) scores for pain, grip strength, pinch strength, and Patient-Rated Wrist Evaluation (PRWE) scores before surgery and at the final follow-up. We analyzed correlations between the resection height and the radiographic and functional outcomes.

RESULTS

The average follow-up period was 42 months. The average VAS score improved from 6.1 ± 2.3 before surgery to 1.7 ± 1.9 after surgery. The average grip strength improved from 18 ± 6 to 19 ± 9 kg, pinch strength from 2.5 ± 1.1 to 4.4 ± 1.7 kg, and PRWE score from 52 ± 23 to 32 ± 24. Carpal deformity (C-L angle of > 15°) was seen in 2 patients at the final follow-up. The deformity was more likely to occur when the resection height was greater than 3 mm.

CONCLUSIONS

Arthroscopic distal scaphoid resection alone can reduce pain and improve functional outcomes for early to mid-stage isolated STT osteoarthritis in patients without dorsal intercalated segment instability deformity. Resection of greater than 3 mm of the distal scaphoid may result in carpal malalignment.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

The Effect of Dorsally Angulated Distal Radius Deformities on Carpal Kinematics: An In Vitro Biomechanical Study

PURPOSE

The purpose was to quantify the effect of distal radius dorsal angulation (DA) on carpal kinematics and the relative roles of the radiocarpal and midcarpal joints during wrist motion.

METHODS

Six cadaveric specimens (69 ± 17 y) were mounted at 90° elbow flexion in a custom wrist motion simulator. The wrist was guided through planar passive flexion and extension motion trials (∼ 5°/s). A custom modular distal radius implant was used to simulate native alignment and 3 distal radius DA deformities (10°, 20°, 30°). An optical tracking system captured carpal bone motion, from which radiocarpal and midcarpal joint motion was determined.

RESULTS

The radiocarpal joint made a greater contribution to wrist motion than the midcarpal joint in flexion, and the midcarpal joint made a greater contribution to motion than the radiocarpal joint in wrist extension. Increasing DA caused the radiocarpal joint contribution to increase throughout the motion arc, with the effect being more pronounced in wrist flexion. Conversely, as DA increased, the midcarpal joint contributed less rotation to the total wrist motion and its overall motion arc decreased; the magnitude of effect was greater in wrist extension. Dorsal angulation resulted in increased lunate flexion with respect to the distal radius.

CONCLUSIONS

Our findings agree with current literature that suggests that, in an uninjured wrist, the radiocarpal joint predominates flexion, and the midcarpal joint predominates extension. In addition, the radiocarpal joint has an amplified contribution in wrist flexion with greater DA malunion.

CLINICAL RELEVANCE

The altered contributions of the radiocarpal and midcarpal joints may contribute to pain, stiffness, and the development of arthritis, which is commonly seen at the radiocarpal joint after malunion of the distal radius.

Force Required to Maintain Reduction of a Preexisting Scapholunate Dissociation

PURPOSE

To determine the force required to maintain reduction of Geissler grade 4 scapholunate dissociations during physiological wrist motions.

METHODS

Fresh-frozen cadaveric wrists with Geissler grade 4 scapholunate dissociations were identified by arthroscopy. Following reduction, a load cell was attached to measure the force across the scapholunate joint at a neutral position and during 4 different wrist motions re-created using a servohydraulic wrist simulator, including a large flexion-extension motion (FEM), small and large dart-thrower's motions (DTMs), and a large DTM with ulnar offset.

RESULTS

Five wrists with isolated preexisting scapholunate interosseous ligament (SLIL) tears were analyzed. The force required to maintain reduction was significantly greater in extension than in flexion during the large FEM and large DTM with ulnar offset. The forces were significantly larger in this study of preexisting SLIL dissociations compared with results from a prior study of acutely sectioned SLILs. In addition, forces to maintain reduction during DTMs were significantly less than forces during FEMs. Finally, a set of 3 wrists with preexisting scapholunate and lunotriquetral interosseous ligament (LTIL) tears were identified and had significantly decreased forces to maintain reduction at maximum extension and had decreased maximal forces during a cycle of motion compared with the wrists with isolated SLIL tears.

CONCLUSIONS

The forces required to maintain reduction of a Geissler grade 4 wrist are higher than forces after acutely sectioned SLIL. The forces are greater in extension than in flexion and less during the DTM compared with the FEM. Wrists with both SLIL and LTIL tears required less force to maintain reduction than those with isolated SLIL tears.

CLINICAL RELEVANCE

This study helps determine the strength of reconstruction required to maintain reduction of a Geissler grade 4 scapholunate dissociation.

Long-Term Functional Results of a Wrist Exercise Program for Patients with Palmar Midcarpal Instability

Background  Patients with palmar midcarpal instability have symptoms of pain, combined with clinical signs of abnormal mobility on stressing the joint, an unpredictable blockade feeling, and a noticeable clunk, in the absence of an underlying trauma. No data are available on the effect of conservative treatment for these patients. Purpose  The purpose of this study was to evaluate the effect and the long-term functional outcomes of a wrist exercise program in patients with palmar midcarpal instability. Patients and Methods  All patients diagnosed with palmar midcarpal instability between 2005 and 2011 were included. Patients completed the Patient-Rated Wrist and Hand Evaluation (PRWHE) and the Short Form-36 health (SF-36) questionnaires, scaled their perceived pain before and after treatment, and indicated the effect of the received treatment. Results  A total of 119 patients diagnosed with palmar midcarpal instability were included. The median follow-up time was 6 years (IQR 4.5-7.0). The median PRWHE score after hand therapy was 35.5 and the median mental component of the SF-36 score was 53.9 and the physical component was 45.2. The median perceived pain reduced from eight to four and the median therapeutic effect of the wrist exercise program was five. Conclusion  Although palmar midcarpal instability remains to be a chronic disease, the effectiveness of our wrist exercise program is promising with acceptable long-term functional results and a good quality of life. Level of Evidence  Level IV, retrospective cohort study.

Dorsal Wrist Plication for Midcarpal Instability

PURPOSE

Midcarpal instability (MCI) is a cause of chronic wrist pain for which treatment remains controversial. This study's purpose was to determine the outcome of a treatment algorithm for MCI that included immobilization and surgical interventions.

METHODS

We prospectively enrolled 23 consecutive patients (12 males, average age 27 years) with 27 symptomatic wrists. All had generalized wrist pain with an average duration of 22 months. All had MCI and a catch-up clunk that reproduced the symptoms. Initial treatment was full immobilization for 6 weeks. When necessary, recurrence after immobilization was treated with an anatomically based surgical procedure to plicate the dorsal capsule and extrinsic ligaments to stabilize the midcarpal joint. Failure of surgical plication was followed by 4-corner intercarpal arthrodesis when necessary. Patients were observed for instability, grip strength, wrist motion, and Patient-Rated Wrist Evaluation.

RESULTS

For 22 wrists there was partial relief of symptoms with full-time cast or orthosis immobilization; however, symptoms quickly returned with mobilization. The other wrists had previously been immobilized and patients refused further nonsurgical care. All patients underwent surgical plication of the dorsum of the wrists. Postoperative follow-up (35 months) showed statistically significant improvements in grip strength and Patient-Rated Wrist Evaluation scores. All patients had improved pain at final follow-up. Most improvement was in female patients aged under 25 years, with hypermobility and without major traumatic or work-related injuries. This contrasted with poorer outcomes in men aged over 25years who had moderate or severe trauma that was mostly work-related. Instability recurred in 2 patients who then had a 4-corner arthrodesis.

CONCLUSIONS

Immobilization was not successful in controlling pain and recurrence of instability in patients with MCI. Surgical midcarpal capsular plication was less effective in men with posttraumatic instability. The capsular plication procedure was successful in young female patients with ligament laxity and a history of only minor or repetitive trauma and no history of major trauma.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

Biomechanical Analysis of Palmar Midcarpal Instability and Treatment by Partial Wrist Arthrodesis

PURPOSE

To create a biomechanical model of palmar midcarpal instability by selective ligament sectioning and to analyze treatment by simulated partial wrist arthrodesis.

METHODS

Nine fresh-frozen cadaver arms were moved through 3 servohydraulic actuated motions and 2 passive wrist mobilizations. The dorsal radiocarpal, triquetrohamate, scaphocapitate, and scaphotrapeziotrapezoid ligaments were sectioned to replicate palmar midcarpal instability. Kinematic data for the scaphoid, lunate, and triquetrum were recorded before and after ligament sectioning and again after simulated triquetrohamate arthrodesis (TqHA) and radiolunate arthrodesis (RLA).

RESULTS

Following ligament sectioning, the model we created for palmar midcarpal instability was characterized by significant increases in (1) lunate angular velocity, (2) lunate flexion-extension, and (3) dorsal/volar motion of the capitate during dorsal/volar mobilizations. Simulated TqHA caused significantly more scaphoid flexion and less extension during the wrist radioulnar deviation motion. It also increased the amount of lunate and triquetral extension during wrist flexion-extension. Simulated RLA significantly reduced scaphoid flexion during both wrist radioulnar deviation and flexion-extension.

CONCLUSIONS

Both simulated arthrodeses eliminate wrist clunking and may be of value in treating palmar midcarpal instability. However, simulated RLA reduces proximal row motion whereas simulated TqHA alters how the proximal row moves. Long-term clinical studies are needed to determine if these changes are detrimental.

CLINICAL RELEVANCE

Palmar midcarpal instability is poorly understood, with most treatments based on pathomechanical assumptions. This study provides information that clinicians can use to design better treatment strategies for this unsolved condition.

Wrist cineradiography: a protocol for diagnosing carpal instability

Carpal instability is often related to ruptured or lax carpal ligaments. Wrist cineradiography has been shown to be a good modality for diagnosing carpal instability. To create uniformity in obtaining and assessing wrist cineradiography, a wrist cineradiography protocol is desirable. This protocol will focus on wrist cineradiography for diagnosing carpal instabilities. It describes the pathologic motions of the carpus and correlates these with a clinical diagnosis.

LEVEL OF EVIDENCE

III.

Palmer Midcarpal Instability: An Algorithm of Diagnosis and Surgical Management

Background  Palmar midcarpal instability (PMCI) is an uncommon form of nondissociative carpal instability. However, it is an important cause of chronic ulnar wrist pain. Diagnosis can be difficult and high index of suspicion is mandatory. Pathomechanics and optimal treatment of PMCI remain uncertain. We propose an algorithm of clinical diagnosis and evaluate the outcome of our management. Materials and Methods  Between 2000 and 2011, 16 patients, including 7 males and 9 females, of a mean age of 33.9 diagnosed with PMCI were reviewed for their clinical, radiologic, and arthroscopic features. All patients presented with ulnar wrist pain in their dominant hands except in one. Initial management included a disease-specific anticarpal supination splint. Refractory cases were evaluated by arthroscopy and treated by arthroscopic thermal shrinkage using radiofrequency appliance as an interim or definite surgical intervention. Shrinkage was targeted at the ulnocarpal ligament at the radiocarpal joint and triquetrohamate ligament at the midcarpal joint. Nonresponsive or recurrent cases were managed by a novel technique of dorsal radiocarpal ligament reconstruction procedure using a pisiform-based split flexor carpi ulnaris (FCU) tendon graft. Results  In all cases, the midcarpal clunk test was positive with pain. Other common clinical features included lax ulnar column, carpal supination, volar sagging of the wrist, increased pisostyloid distance, wrist pain aggravated by passive hand supination and not by passive forearm supination, and increased wrist pain upon resisted pronation, which could be partially alleviated by manually supporting the pisostyloid interval. Common arthroscopic findings were excessive joint space at triquetrohamate interval and reactive synovitis over the ulnar compartments. Nine patients (56.3%) responded well to splinting alone at an average follow-up of 3.3 years. Arthroscopic thermal shrinkage was performed in five patients with recurrence in two patients. Five patients received split FCU tendon graft for ligament reconstruction. All patients showed improvement in the wrist performance score (preop 21.0, postop 36.6 out of 40) and pain score (preop 10.0, postop 2.2 out of 20) at the final follow-up of average 86 months (range: 19-155 months). Grip strength improved from 66.9 to 82.0% of the contralateral side. Wrist motion slightly decreased from a flexion/extension arc of 132 to 125 degrees. Three patients were totally pain free, one had mild pain, and one had moderate fluctuating pain. All patients returned to their original works. X-ray showed no arthrosis. Conclusion  PMCI is an uncommon but significant cause of chronic ulnar wrist pain. We have developed a clinical algorithm for diagnosis of the condition. The natural history seems to favor a benign course. Conservative treatment with an anticarpal supination splint is recommended as the initial management. Surgical options for resistant cases include arthroscopic thermal shrinkage or soft tissue reconstruction. The reconstruction of the dorsal radiocarpal ligament using a pisiform-based split FCU tendon graft provides reliable restoration of the carpal stability with good long-term outcome and few complications. This should be considered a viable alternative to limited carpal fusion.

Midcarpal Instability: The Role of Wrist Arthroscopy

The evidence behind management options for midcarpal instability (MCI) is scarce, relying solely on case series. Established treatments cause significant loss of wrist motion. As understanding of the condition has progressed, surgeons have been trying soft tissue techniques. The treatment option should be chosen for the appropriate type and grade of MCI. The Hargreaves grading system for palmar MCI aids treatment decision-making. A possible role for arthroscopy in treatment of MCI has been developed using arthroscopic thermal capsular shrinkage, appropriate for cases with dynamic instabilities. Static deformities require a soft tissue reconstruction or a partial wrist fusion.

[Ligament injuries of the wrist]

The distal radioulnar joint, the triangular fibrocartilage complex (TFCC) and the wrist are stabilized by many ligaments allowing not only a wide range of motion but also providing sufficient stability. The complex arrangement of carpal ligaments and prosupination around the forearm joint enables multiaxial motion patterns. In the wrist, intra-articular ligaments can be differentiated from extra-articular capsular ligaments as well as intrinsic and extrinsic ligament courses. Imaging is essential for classification of dynamic and static instability patterns. This review article illustrates the ligamentous anatomy of the wrist, the symptoms of carpal instability as well as the diagnostic capability of projection radiography, cinematography, computed tomography (CT) arthrography, magnetic resonance imaging (MRI) and MR arthrography.

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.

Understanding carpal instability: a radiographic perspective

The wrist is disposed to a variety of instability patterns owing to its complex anatomical and biomechanical properties. Various classification schemes have been proposed to describe the different patterns of carpal instability, of which the Mayo classification is the most commonly used. Understanding the concepts and pertinent terminology of this classification scheme is important for the correct interpretation of images and optimal communication with referring physicians. Standard wrist radiographs are the first line of imaging in carpal instability. Additional information may be obtained with the use of stress radiographs and other imaging modalities.

Volar Central Portal in Wrist Arthroscopy

Background Nowadays, the wrist is not limited to a dorsal visualization; the joint can be thought of as a "box," which can be visualized from almost every perspective. The purpose of this study was to describe a new volar central portal for the wrist, following three principles: a single incision that allows access to both the radiocarpal and midcarpal joints, centered on the lunate, with the volar structures at risk protected not only by retractors, but also by tendons. Description of Technique The incision begins in the distal wrist crease and extended 1.5 cm proximally up to the proximal wrist crease, following the axis of the third intermetacarpal space. The flexor superficialis tendons are identified and retracted toward the radial side. Next, the fourth and fifth flexor digitorum profundus tendons are retracted toward the ulnar side, while the third and second tendons are retracted toward the radial side. The volar central midcarpal portal is performed under direct vision just over the anterior horn of the lunate through the Poirier space. The volar central radiocarpal portal is created under the lunate through the interval between the ulnocarpal ligaments and the short radioulnar ligament. Methods An anatomical study was performed on 14 cadaver specimens. Two data were recorded: iatrogenic injuries of the structures at risk and the distances to the structures at risk. Results The median (interquartile range [IQR]) distances from the volar central radiocarpal portal to the median nerve, palmar cutaneous branch of the median nerve, and ulnar neurovascular bundle were 10.5 (7.8-15.0), 18.5 (15.8-20.3), and 7.0 (5.0-10.5) mm, respectively. The median (IQR) distances from the volar central midcarpal portal to the median nerve, palmar cutaneous branch of the median nerve, and ulnar neurovascular bundle were 7.0 (4.8-10.3), 16.0 (14.8-19.0), and 4.5 (3.8-9.0) mm, respectively. No iatrogenic injuries were observed. Conclusion The volar central portal is reproducible and safe. The risk of iatrogenic injury is low. The capsule is pierced through one of its thinner portions, and both the radiocarpal and midcarpal joints can be inspected through one single incision.

Imaging in carpal instability

Carpal instability is a complex and heterogeneous clinical condition. Management requires accurate identification of structural injury with an understanding of the resultant movement (kinematic) and load transfer (kinetic) failure. Static imaging techniques, such as plain film radiography, stress views, ultrasound, magnetic resonance, MR arthrography and computerized tomography arthrography, may accurately depict major wrist ligamentous injury. Dynamic ultrasound and videofluoroscopy may demonstrate dynamic instability and kinematic dysfunction. There is a growing evidence base for the diagnostic accuracy of these techniques in detecting intrinsic ligament tears, but there are limitations. Evidence of their efficacy and relevance in detection of non-dissociative carpal instability and extrinsic ligament tears is weak. Further research into the accuracy of existing imaging modalities is still required. Novel techniques, including four-dimensional computerized tomography and magnetic resonance, can evaluate both cross-sectional and functional carpal anatomy. This is a narrative review of level-III studies evaluating the role of imaging in carpal instability.

Conservative management of midcarpal instability

Midcarpal instability is a complex condition that can present in various forms, from mild pain to debilitating subluxation. Once diagnosed, treatment guidelines for hand therapy are limited by the scarcity of high-level evidence. Evidence does exist for use of proprioceptive awareness and neuromuscular rehabilitation for instability of the knee, shoulder and ankle joint, but studies of similar programmes for the wrist joint have not been published. The purpose of this review is to examine the evidence supporting current concepts in the non-operative management of midcarpal instability, and to provide recommendations for the management of this condition with hand therapy.

Midcarpal instability

Midcarpal instability is a collective term for a number of conditions where the instability of the wrist is predominantly between the proximal and distal carpal rows. It has been regarded as relatively rare and infrequently requires surgical treatment. Palmar midcarpal instability is the most commonly found type of midcarpal instability and can be responsible for causing a clunking and painful wrist. The diagnosis is made on clinical grounds using the midcarpal instability provocative tests. Standard imaging and arthroscopic inspection do not usually confirm a definite diagnosis, but are important in excluding other pathologies. The classification and staging has been described using the extent of palmar translocation of the distal carpal row, which is elicited on passive stress tests. As this is a functional instability, it may be that a functional staging description might be better, and a proposed scheme is described. Treatment options including partial wrist fusions, tenodesis stabilizations and arthroscopic capsular shrinkage have been described in small case series with limited follow-up. There are no comparative series or randomized studies because of the relative rarity of this condition.

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.

Carpal Ligament Anatomy and Biomechanics

A fundamental understanding of the ligamentous anatomy of the wrist is critical for any physician attempting to treat carpal instability. The anatomy of the wrist is complex, not only because of the number of named structures and their geometry but also because of the inconsistencies in describing these ligaments. The complex anatomy of the wrist is described through a review of the carpal ligaments and their effect on normal carpal motion. Mastery of this topic facilitates the physician's understanding of the patterns of instability that are seen clinically.

Physical Examination of the Wrist: Useful Provocative Maneuvers

Chronic wrist pain resulting from partial interosseous ligament injury remains a diagnostic dilemma for many hand and orthopedic surgeons. Overuse of costly diagnostic studies including magnetic resonance imaging, computed tomography scans, and bone scans can be further frustrating to the clinician because of their inconsistent specificity and reliability in these cases. Physical diagnosis is an effective (and underused) means of establishing a working diagnosis of partial ligament injury to the wrist. Carefully performed provocative maneuvers can be used by the clinician to reproduce the precise character of a patient's problem, reliably establish a working diagnosis, and initiate a plan of treatment. Using precise physical examination techniques, the examiner introduces energy into the wrist in a manner that puts load on specific support ligaments of the carpus, leading to an accurate diagnosis. This article provides a broad spectrum of physical diagnostic tools to help the surgeon develop a working diagnosis of partial wrist ligament injuries in the face of chronic wrist pain and normal x-rays.

Wide field of view computed tomography and mid-carpal instability: the value of the sagittal radius-lunate-capitate axis--preliminary experience

PURPOSE

Dynamic four dimensional (4D) computed tomography (CT) has recently emerged as a practical method for evaluating complex functional abnormality of joints. We retrospectively analysed 4D CT studies undertaken as part of the clinical management of hand and wrist symptoms. We present our initial experience of 4D CT in the assessment of functional abnormalities of the wrist in a group of patients with mid carpal instability (MCI), specifically carpal instability non-dissociative. We aim to highlight unique features in assessment of the radius-lunate-capitate (RLC) axis which allows insight and understanding of abnormalities in function, not just morphology, which may be contributing to symptoms.

MATERIALS AND METHODS

Wide field of view multi-detector CT scanner (320 slices, 0.5 mm detector thickness) was used to acquire bilateral continuous motion assessment in hand flexion and extension. A maximum z-axis coverage of 16 cm was available for each acquisition, and a large field of view (FOV) was used. Due to the volume acquisition during motion, reconstructions at multiple time points were undertaken. Dynamic and anatomically targeted multi-planar-reconstructions (MPRs) were then used to establish the kinematic functionality of the joint.

RESULTS

Our initial cohort of 20 patients was reviewed. Three findings were identified which were present either in isolation or in combination. These are vacuum phenomenon, triggering of the lunate and capitate subluxation. We provide 4D CT representations of each and highlight features considered of clinical importance and their significance. We also briefly discuss how the current classifications of dynamic wrist abnormalities may alter with the supplementary information provided by dynamic 4D CT MSK acquisitions.

CONCLUSION

4D CT has provided a unique insight into motion disorders. We highlight our early experience with the ability of 4D CT to investigate the RLC axis and three signs which have provided a unique assessment of MCI. This improved assessment of wrist motion disorders has highlighted sufficient differences in the dynamic CT classifications we have described and suggests that further research may result in refinement of the MCI classification system.

A new technique for the treatment of midcarpal instability

Extensor carpi radialis brevis (ECRB) transfer to the hamate bone is a novel procedure that offers a new surgical treatment option for select patients with midcarpal instability (MCI) who do not respond to conservative treatment. We present our early experience with this procedure. In total, 12 patients (13 wrists) were reviewed with a follow-up duration ranging from 1 to 6 years. Complications and changes in active range of motion (AROM) were noted. Patient related outcome was measured using the Patient Rated Wrist/Hand Evaluation (PRWHE) questionnaire, amongst others. Two patients failed to show a positive response to the surgery. ECRB transfer to the ulnar side of the wrist is a new procedure that offers a potential option for the surgical treatment of MCI in select patients; however, further biomechanical and clinical studies are required. The level of evidence for this study is IV (therapeutic).

Soft tissue stabilization for palmar midcarpal instability using a palmaris longus tendon graft

PURPOSE

To report the results of a technique of soft tissue stabilization for palmar midcarpal instability using a palmaris longus graft.

METHODS

In patients' symptomatic wrists with palmar midcarpal instability that had failed conservative management, we used a dorsal approach and stabilized the hamate and triquetrum by reconstructing the dorsal triquetrohamate ligament. The palmaris longus tendon graft was fixed with bone anchors. Seven wrists in 6 patients were available for follow-up at a mean of 28 months (range, 17-37 mo).

RESULTS

There was an overall meaningful improvement in function (mean preoperative Disabilities of the Arm, Shoulder, and Hand score, 49 preoperatively, 28 postoperatively). There was a significant increase in grip strength from 15 to 21 kg. At final follow-up, 2 patients had moderate pain. The others had mild or no pain. Four patients returned to their previous occupation or activity. Patients retained full pronation and supination. When compared with the normal side, flexion was reduced to 71%, extension to 81%, radial deviation to 90%, and ulnar deviation to 65% of the opposite side. Although the mean results show an improvement, one patient had a poor result with deterioration in Disabilities of the Arm, Shoulder, and Hand score in spite of a clinically stable wrist, and another had clinical evidence of recurrent instability during pregnancy. One patient had residual symptoms from a prominent bone anchor.

CONCLUSIONS

Overall, this technique showed good medium-term results in most of our patients. It retained some midcarpal mobility, eliminated clunking in most patients, and provided a noteworthy improvement in grip strength and function. We continue to use this technique for patients with symptomatic midcarpal instability, but it requires further evaluation with larger patient numbers and a longer follow-up to assess its overall value.

Estimation of hand and wrist muscle capacities in rock climbers

PURPOSE

This study investigated the hand and wrist muscle capacities among expert rock climbers and compared them with those of non-climbers. The objective was to identify the adaptations resulting from several years of climbing practice.

METHODS

Twelve climbers (nine males and three females) and 13 non-climber males participated in this study. Each subject performed a set of maximal voluntary contractions about the wrist and the metacarpo-phalengeal joints during which net joint moments and electromyographic activities were recorded. From this data set, the muscle capacities of the five main muscle groups of the hand (wrist flexors, wrist extensors, finger flexors, finger extensors and intrinsic muscles) were estimated using a biomechanical model. This process consisted in adjusting the physiological cross-sectional area (PCSA) and the maximal muscle stress value from an initial generic model.

RESULTS

Results obtained from the model provided several new pieces of information compared to the analysis of only the net joint moments. Particularly, the capacities of the climbers were 37.1 % higher for finger flexors compared to non-climbers and were similar for finger extensor and for the other muscle groups. Climbers thus presented a greater imbalance between flexor and extensor capacities which suggests a potential risk of pathologies.

CONCLUSIONS

The practice of climbing not only increased the strength of climbers but also resulted in specific adaptations among hand muscles. The proposed method and the obtained data could be re-used to optimize the training programs as well as the rehabilitation processes following hand pathologies.

An innovative orthotic design for midcarpal instability, non-dissociative: mobility with stability

Assisting carpal instability patients with regaining pain free and symptom free movement is a primary goal of therapy. This author describes her version of an orthotic device for carpal instability non-dissociative. She also describe her typical treatment plan for these patients.

Scaphoid overstuffing: the effects of the dimensions of scaphoid reconstruction on scapholunate alignment

PURPOSE

Osteochondral replacement of the proximal scaphoid has been reported using a vascularized flap from the medial femoral trochlea. A concern with this technique is the loss of stability of the scapholunate relationship with resection of the scaphoid proximal pole. Overexpansion of the scaphoid dimensions (overstuffing) during scaphoid reconstruction with the osteochondral flap may play a role in maintaining scapholunate alignment. Our purpose was to determine if overstuffing the scaphoid can correct rotatory carpal instability in a cadaveric model studied radiographically.

METHODS

The radiolunate angle and scapholunate interval were measured for 5 fresh cadaver wrists. We completely incised the scapholunate interosseous ligament and performed an osteotomy to excise the proximal third of the scaphoid to simulate a proximal pole deficiency nonunion and create a dorsal intercalated segmental instability deformity. Radiographic measurements were repeated. The proximal pole of the scaphoid was replaced with its original piece of bone; radiographic measurements were repeated without scapholunate ligament repair. The osteotomy site was overstuffed with a 4-mm sawbone spacer without scapholunate ligament repair, and radiographs were obtained.

RESULTS

Sectioning of scapholunate ligaments and proximal pole excision successfully created carpal instability demonstrated by abnormal radiolunate angles. Without ligament repair, proximal pole replacement did not restore normal radiolunate angles. Expansion of the scaphoid dimensions corrected radiolunate angles on lateral unloaded radiographs and improved scapholunate intervals on clenched fist radiographs. These findings were statistically significant compared with the unexpanded (replaced) scaphoid.

CONCLUSIONS

These findings suggest that scaphoid reconstruction that results in expansion of the scaphoid's normal dimensions will restore carpal alignment without scapholunate ligament reconstruction.

CLINICAL RELEVANCE

Osteochondral reconstruction of difficult proximal pole nonunions may not require any preservation or reconstruction of scapholunate integrity if the reconstruction expands the normal dimensions of the native scaphoid. Scapholunate interval and carpal alignment may be restored by scaphoid over stuffing. The effects on increased contact pressure and range of motion require further investigation.

Four-dimensional computed tomography and trigger lunate syndrome

BACKGROUND

A 22-year-old man with no history of trauma and normal plain films, ultrasound, and magnetic resonance imaging presents with several months of increasingly severe pain and clicking in the right wrist. He is clinically diagnosed with midcarpal instability and undergoes a 4-dimensional computed tomography scan of his wrist for further evaluation.

METHODS

The motion of the subject's lunate was evaluated through a full arc of flexion and extension as well as radial and ulnar deviation. A comparison was made with the lunate of an asymptomatic patient demonstrating the same motions.

RESULTS

The symptomatic lunate demonstrated early smooth motion, followed by cessation of motion, and then again followed by smooth catch up motion. The asymptomatic patient demonstrated smooth lunate motion throughout the study.

DISCUSSION

The lunate motion, with an abrupt cessation and recommencement of flexion/extension, was consistent with a triggering phenomenon. This trigger lunate motion abnormality, although consistent with the "clunking" sensation often described during the physical examination, has not been previously recognized radiographically as a feature of midcarpal instability.

Four-dimensional real-time cine images of wrist joint kinematics using dual source CT with minimal time increment scanning

PURPOSE

To validate the feasibility of real time kinematography with four-dimensional (4D) dynamic functional wrist joint imaging using dual source CT.

MATERIALS AND METHODS

Two healthy volunteers performed radioulnar deviation and pronation- supination wrist motions for 10 s and 4 s per cycle in a dual source CT scanner. Scan and reconstruction protocols were set to optimize temporal resolution. Cine images of the reconstructed carpal bone of the moving wrist were recorded. The quality of the images and radiation dosage were evaluated.

RESULTS

The 4D cine images obtained during 4 s and 10 s of radioulnar motion showed a smooth stream of movement with good quality and little noise or artifact. Images from the pronation-supination motion showed noise with a masked surface contour. The temporal resolution was optimized at 0.28 s.

CONCLUSION

Using dual source CT, 4D cine images of in vivo kinematics of wrist joint movement were obtained and found to have a shorter scan time, improved temporal resolution and lower radiation dosages compared with those previously reported.

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.

Midcarpal instability: a radiological perspective

Midcarpal instability (MCI) is the result of complex abnormal carpal motion at the midcarpal joint of the wrist. It is a form of non-dissociative carpal instability (CIND) and can be caused by various combinations of extrinsic ligament injuries that then result in one of several subtypes of MCI. The complex patterns of injury and the kinematics are further complicated by competing theories, terminology and classifications of MCI. Palmar, dorsal, ulna midcarpal instability, and capitolunate or chronic capitolunate instability are all descriptions of types of MCI with often overlapping features. Palmar midcarpal instability (PMCI) is the most commonly reported type of MCI. It has been described as resulting from deficiencies in the ulna limb of the palmar arcuate ligament (triquetrohamate-capitate) or the dorsal radiotriquetral ligaments, or both. Unstable carpal articulations can be treated with limited carpal arthrodesis or the ligamentous defects can be treated with capsulorrhaphy or ligament reconstruction. Conventional radiographic abnormalities are usually limited to volar intercalated segment instability (VISI) patterns of carpal alignment and are not specific. For many years stress view radiographs and videofluoroscopy have been the methods of choice for demonstrating carpal instability and abnormal carpal kinematics respectively. Dynamic US can be also used to demonstrate midcarpal dyskinesia including the characteristic triquetral "catch-up" clunk. Tears of the extrinsic ligaments can be demonstrated with MR arthrography, and probably with CT arthrography, but intact yet redundant ligaments are more difficult to identify. The exact role of these investigations in the diagnosis, categorisation and management of midcarpal instability has yet to be determined.

Controlled active mobilization after dorsal capsulodesis to correct capitolunate dissociation

STUDY DESIGN

Case Report. Capitolunate instability is a form of midcarpal instability. If conservative management is unsuccessful, surgical reconstruction is often indicated. However, the literature is limited regarding postoperative management after reconstruction. Often patients are immobilized for a 6- to 12-week period, which can produce secondary complications, including wrist stiffness, tendon adherence, and muscle atrophy. The purpose of the case report was to demonstrate that controlled early mobilization may be implemented postoperatively after dorsal capsulodesis procedures to correct capitolunate instability. This early mobilization may prevent secondary complications, which can be associated with lengthy immobilization periods. A 27-year-old female underwent a dorsal capsulodesis procedure to correct capitolunate instability. The intraoperative findings of the reconstruction and tension on the capsulodesis procedure were communicated to the therapist by the surgeon. This close communication allowed the therapist to institute early controlled mobilization immediately postoperatively using a hinged wrist splint. The patient was followed by our unit for 13 years. Early controlled mobilization using a hinged wrist splint may have maximized the subject's recovery, with no secondary complications. At 13-year follow-up, fluoroscopic and radiographic examination was normal, and no symptoms of pain or instability had reoccurred. In conclusion, early controlled mobilization using a hinged wrist splint may optimize the recovery period while retaining the desired arc of motion that is set intraoperatively.

LEVEL OF EVIDENCE

4.