Scapholunate Instability: Diagnosis and Management - Anatomy, Kinematics, and Clinical Assessment - Part I.

Injuries to the scapholunate joint are the most frequent cause of carpal instability. The sequelae of these injuries account for considerable morbidity, and if left untreated, may lead to scapholunate advanced collapse and progressive deterioration of the carpus. Rupture of the scapholunate interosseous ligament and its critical stabilizers causes dyssynchronous motion between the scaphoid and lunate. Additional ligament injury or attenuation leads to rotary subluxation of the scaphoid and increased scapholunate gap. Intervention for scapholunate instability is aimed at halting the degenerative process by restoring ligament integrity and normalizing carpal kinematics. In the first section of this review, we discuss the anatomy, kinematics, and biomechanical properties of the scapholunate ligament as well as its critical ligament stabilizers. We provide a foundation for understanding the spectrum of scapholunate ligament instability and incorporate meaningful new anatomical insights that influence treatment considerations. The purpose is to provide an update regarding the anatomy of the scapholunate ligament complex, importance of the critical ligament stabilizers of the proximal carpal row, introduction of safe technique to surgically expose the scaphoid and lunate, as well as pathoanatomy as it pertains to the treatment of scapholunate dissociation. In the second section of this review, we propose a novel ligament-based treatment algorithm based on the stage of injury, degree and nature of ligament damage, and presence of arthritic changes.

Dorsal Extrinsic Ligament Injury and Static Scapholunate Diastasis on Magnetic Resonance Imaging Scans.

PURPOSE: Current biomechanical data suggest that static scapholunate (SL) ligament dissociation occurs only when there is loss of competence of the extrinsic ligaments either acutely or with attenuation over time. We aimed to identify whether patients with an SL gap greater than 2 mm demonstrated concomitant dorsal radiocarpal ligament (DRC) and dorsal intercarpal ligament (DIC) ligament changes on magnetic resonance imaging (MRI) scans that were identified as having an SL ligament tear. METHODS: We included 90 patients who had a posttraumatic MRI scan of the wrist diagnosed with an SL injury. We recorded basic demographics; 2 attending fellowship-trained musculoskeletal radiologists evaluated the integrity of the SL, DRC, and DIC ligaments and graded these as normal, low-grade injury (sprain or partial tear) or full-thickness tear. The association between the integrity of the DRC and DIC ligaments and the presence of a scapholunate gap of 2 mm or greater was analyzed. RESULTS: A total of 48 patients (53%) had an SL distance of 2 mm or greater on MRI. Of these patients, 28 (58%) had a partial or total tear of the DIC and/or DRC ligament. Compared with patients with an SL interval less than 2 mm, patients with an SL interval 2 mm or greater more often demonstrated DIC signal change (31% vs 12%), DRC signal change (52% vs 14%), or combined or isolated DIC and/or DRC signal change (52% vs 14%). CONCLUSIONS: Dorsal extrinsic ligaments demonstrate MRI signal change suggestive of acute or chronic injury in patients with an SL interval 2 mm or greater more often than in patients with an SL interval less than 2 mm. These results reinforce that MRI findings of SL ligament tear need to be interpreted in a larger context, perhaps with additional attention to the DIC and DRC appearance upon MRI. In addition, MRI evaluation of dorsal extrinsic ligaments may aid in clinical decision-making for patients with SL injury. TYPE OF STUDY/LEVEL OF EVIDENCE: Diagnostic IV.

Cumulative incidence of carpal instability 12-24 months after fall onto outstretched hand.

STUDY DESIGN: Descriptive Epidemiological Study. INTRODUCTION: Ligament tears between carpal bones are easily missed on initial presentation, but can have potentially debilitating effects on the patient if they progress to an instability. They are usually the result of a fall onto an outstretched hand with the wrist in hyperextension. Current incidence of carpal instability after these falls is unknown. PURPOSE OF THE STUDY: Using established clinical and radiological measures, we sought to establish the cumulative incidence of carpal instability in people who have fallen onto an outstretched hand in the second year after injury. We also sought to describe its relationship with functional impairment. METHODS: We used emergency department records of an inner-urban tertiary hospital to contact all patients who presented with wrist pain following fall onto outstretched hand who were between one and two years after injury. Carpal instability was defined by blinded radiological evaluations and provocative clinical tests, including Scaphoid Shift (Watson's) test, Ballottement, and mid-carpal shift test. Wrist-related pain and disability was measured using the Patient-Rated Wrist and Hand Evaluation. RESULTS: Of the 279 potentially eligible cases, only 146 were contactable, and fifty (28 male, 22 female; mean age of 48 years) attended for assessment. We found a cumulative incidence of 44% of carpal instability within the second year after injury. Of these, 12 (24%) cases had scapho-lunate instability, 12 (24%) had luno-triquetral instability and 7 (14%) had mid-carpal instability. There were no significant correlations between clinically confirmed carpal instability and pain, function, or work participation. DISCUSSION AND CONCLUSION: This study found a higher than anticipated cumulative incidence of carpal instability in the second year after injury, which may reflect volunteer bias. Patients should be advised to monitor symptoms in the year after injury and seek a review if symptoms of pain, clicking or clunking arise. LEVEL OF EVIDENCE: II.

Long-Term Outcomes After Distal Scaphoid Fractures: A 10-Year Follow-Up.

PURPOSE: The aim of this study was to evaluate the functional, clinical, and radiological outcome 10 years after distal scaphoid fractures. METHODS: From a prospective epidemiological study on posttraumatic radial-sided wrist pain, we evaluated 41 cases of distal scaphoid fractures. All cases had been treated nonsurgically in a thumb spica cast. Patients were examined using radiographs, magnetic resonance imaging and computed tomography at the time of injury and with computed tomography after a median of 10 years (range, 8-11 years). Fractures were classified according to a modified Prosser classification system. The primary outcome was assessment of self-reported function using Disabilities of the Arm, Shoulder, and Hand (DASH) and Patient-Reported Wrist Evaluation (PRWE). Secondary outcomes were clinical status (range of motion and grip and pinch strength) and to evaluate fracture healing and arthritis in the scaphotrapezium-trapezoid (STT) joint. RESULTS: Functional impairment and pain scores at follow-up were low: median DASH score 2, median PRWE 0, and median visual analog scale (VAS) pain score 0. We found no impairment in range of motion or strength. We found 26 type I fractures, 12 type IIA, 1 type IIC, and 2 type IV. There was 1 asymptomatic nonunion in a type I fracture. Computed tomography revealed arthritis in the STT joint in 7 out of 41 wrists, none of which caused clinical symptoms. CONCLUSIONS: From an 8- to 11-year perspective, patients with distal scaphoid fractures report normal self-assessed hand function as well as good wrist motion and strength. The risk for development of posttraumatic STT arthritis was low. TYPE OF STUDY/LEVEL OF EVIDENCE: Prognostic II.

Osteoclasts are recruited to the subchondral bone in naturally occurring post-traumatic equine carpal osteoarthritis and may contribute to cartilage degradation.

UNLABELLED: The role of osteoclasts in osteochondral degeneration in osteoarthritis (OA) has rarely been investigated in spontaneous disease or animal models of OA. OBJECTIVE: The objectives of the current study were to investigate osteoclast density and location in post-traumatic OA (PTOA) and control specimens from racehorses. METHOD: Cores were harvested from a site in the equine third carpal bone, that undergoes repetitive, high intensity loading. Histological and immunohistochemical (Cathepsin K and Receptor-activator of Nuclear Factor kappa-ß ligand (RANKL)) stained sections were scored (global and subregional) and the osteoclast density calculated. The cartilage histological scores were compared with osteoclast density and RANKL scores. RESULTS: There was a greater density of osteoclasts in PTOA samples and they were preferentially located in the subchondral bone plate. RANKL scores positively correlated to the scores of cartilage degeneration and the osteoclast density. The relationship between hyaline articular cartilage RANKL score and osteoclast density was stronger than that of the subchondral bone RANKL score suggesting that cartilage RANKL may have a role in recruiting osteoclasts. The RANKL score in the articular calcified cartilage correlated with the number of microcracks also suggesting that osteoclasts recruited by RANKL may contribute to calcified cartilage degeneration in PTOA. CONCLUSION: Our results support the hypothesis that osteoclasts are recruited during the progression of spontaneous equine carpal PTOA by cartilage RANKL, contributing to calcified cartilage microcracks and focal subchondral bone loss.

Orthotic intervention incorporating the dart-thrower's motion as part of conservative management guidelines for treatment of scapholunate injury.

STUDY DESIGN: Case series. INTRODUCTION: This paper describes conservative guidelines for the management of scapho-lunate interosseous ligament (SLIL) injury including fabrication of an orthosis that restricts active wrist movement to the dart-throwers (DTM) plane. PURPOSE OF THE STUDY: The dart throwers' orthosis (DTO) was designed as a response to biomechanical studies suggesting that restraining motion to the DTM would off-load a deficient SLIL. METHODS: After six weeks of wearing the DTO, the 5 patients in this case series initiated an exercise program that incorporated wrist proprioceptive training and specific muscle strengthening. DISCUSSION: The DTO was designed to incorporate controlled movement in order to better integrate the secondary wrist stabilizers in wrists that had a deficient SLIL. The orthosis and the exercise program harnessed proprioceptive influences using active motion within the DTM plane, and stimulated mechanoreceptors so as to enhance stability. RESULTS: All patients demonstrated improvement in subjective and objective outcomes including self-reported pain and function. CONCLUSIONS: Orthotic intervention that controls motion within the DTM, combined with an appropriate proprioceptive rehabilitation program, may provide a viable conservative treatment option for patients with a similar clinical presentation. LEVEL OF EVIDENCE: 4.

Biomechanical Analysis of Scapholunate Ligament Repair Techniques.

PURPOSE: To evaluate the biomechanical properties of 3 scapholunate repair techniques. METHODS: In 51 cadavers, the scapholunate ligament was exposed through a dorsal approach, incised at its scaphoid insertion, and repaired using 1 of 3 techniques: 2 single-loaded suture anchors, 2 double-loaded suture anchors, or 2 transosseous sutures. Twenty-four repaired specimens underwent load to failure (LTF) testing using tensile distraction on a servo-hydraulic machine. Twenty-seven specimens underwent cyclical testing to measure gap formation at the scapholunate joint. RESULTS: The mode of failure was suture pullout through the substance of the ligament in 22 specimens, failure at the bone suture interface in 1, and anchor pullout in 1. Double-loaded anchor repairs demonstrated a significantly higher mean ultimate LTF compared with single-loaded anchor (91 N vs 35 N) and transosseous (91 N vs 60 N) repairs. Transosseous repairs demonstrated a higher mean ultimate LTF compared with single-loaded suture repairs (60 N vs 35 N). After 300 cycles, the average gap for the transosseous repair group was double that for the single- and double-loaded repairs, although not statistically significant. CONCLUSIONS: Primary scapholunate ligament repairs using double-loaded suture anchors demonstrated significantly higher strength compared with single-loaded anchors and transosseous repairs. On cyclic loading, transosseous repairs demonstrated the greatest gap formation with no measurable difference between single- and double-loaded repairs. CLINICAL RELEVANCE: In a cadaveric model for primary repairs, double-loaded suture anchors demonstrated the highest LTF and offer a similar but unproven performance in vivo.

Complex transradial carpal dislocation in a Professional Pianist: Case Report.

Carpal fracture-dislocation associated to distal radius fractures is an uncommon injury of the wrist. Clinical assessment, instrumental diagnosis and treatment are all challenges for the surgeon. In addition, the prognosis in high-functioning patients is nearly always poor. The authors describe an early diagnosis of scapholunate dissociation and joint capsule tear associated with radial styloid and triquetral fractures in a 39-year-old professional piano player. A dorsal approach was used to reduce and fixate the fracture with k-wires, and to repair soft-tissue injuries with a Titanium micro-anchor. Early controlled mobilization was prescribed post-operatively. No other similar investigations were found because of the various associated fractures in the current case study, which normally excludes subjects from retrospective outcome studies on wrist ligament repair. Early diagnosis and surgical management associated with early controlled mobilization resulted in excellent clinical outcomes, according to radiograph imaging, the Italian version of the DASH score (Disabilities of the Arm, Shoulder and Hand), goniometry and dynamometry.

Excision of the deep branch of the lateral palmar nerve of horses to resolve lameness caused by proximal suspensory desmitis.

OBJECTIVE: To assess outcome after neurectomy of the deep branch of the lateral palmar nerve (DBLPaN) as a treatment for horses with persistent lameness associated with chronic proximal suspensory desmitis (PSD) of the thoracic limb. STUDY DESIGN: Case series. ANIMALS: Adult, mixed-breed horses (n = 4), weighing 510-585 kg, used for amateur show-jumping. METHODS: Records of 4 horses chronically lame because of PSD of one or both thoracic limbs that were treated by neurectomy of the DBLPaN were reviewed. The site of pain causing lameness was localized using regional anesthesia. The proximal aspect of the suspensory ligament of the affected limb(s) of all horses were enlarged on ultrasonographic examination, but fiber disruption was not observed. All horses remained lame after conservative therapy. Neurectomy was performed with the horses anesthetized and positioned in dorsal recumbency. RESULTS: All 4 horses were sound at 6 weeks and remained sound for at least 12 months after neurectomy. CONCLUSION: Lameness in horses caused by chronic PSD can be resolved by neurectomy of the DBLPaN in horses that are refractory to conservative management.

Scapholunate instability: current concepts in diagnosis and management.

Injuries to the scapholunate joint are the most frequent cause of carpal instability and account for a considerable degree of wrist dysfunction, lost time from work, and interference with activities. Although it is insufficient to cause abnormal carpal posture or collapse on static radiographs, an isolated injury to the scapholunate interosseous ligament may be the harbinger of a relentless progression to abnormal joint mechanics, cartilage wear, and degenerative changes. Intervention for scapholunate instability is aimed at arresting the degenerative process by restoring ligament continuity and normalizing carpal kinematics. In this review, we discuss the anatomy, kinematics, and biomechanical properties of the scapholunate articulation and provide a foundation for understanding the spectrum of scapholunate ligament instability. We propose an algorithm for treatment based on the stage of injury and the degree of secondary ligamentous damage and arthritic change.

Perilunate dislocations and fracture dislocations.

Perilunate dislocations and fracture dislocations are high-energy injuries that can result in pain, stiffness, weakness, or disability if inappropriately treated. Prompt recognition and surgical treatment with anatomic reduction of carpal malalignment improve the likelihood of optimal, long-term clinical success and patient satisfaction. The progressive development of radiographic evidence of arthrosis is common but has not been shown to consistently correlate with worse patient function and outcomes.

Ulnar-sided wrist pain: evaluation and treatment of triangular fibrocartilage complex tears, ulnocarpal impaction syndrome, and lunotriquetral ligament tears.

Ulnar-sided wrist pain is a common cause of upper extremity disability. Presentation can vary from acute traumatic injuries to chronic degenerative conditions. Because of its overlapping anatomy, complex differential diagnosis, and varied treatment outcomes, the ulnar side of the wrist has been referred to as the "black box" of the wrist, and its pathology has been compared with low back pain. Common causes of ulnar-sided wrist pain include triangular fibrocartilaginous complex injuries, lunotriquetrial ligament injuries, and ulnar impaction syndrome.

Arthroscopic gap distance can predict the degree of scapholunate ligament tears: a cadaver study.

BACKGROUND: Midcarpal joint arthroscopy is essential for diagnosing scapholunate (SL) instability, but a discrepancy may exist between the grade of arthroscopic evaluation and the extent of SL ligament tears. This study aimed to investigate whether the magnitude of arthroscopic SL gap distance could predict the extent of ligamentous disruptions in a simulated SL dissociation model. METHODS: Eight upper extremities of fresh cadavers were analyzed. Static and dynamic SL gap distances were measured with using custom-made probes via midcarpal arthroscopy in intact wrists following sequential sectioning of the SL stabilizing ligaments. Comparisons of static and dynamic SL gaps between stages were conducted using analysis of variance followed by the Games-Howell test. Receiver operating characteristic (ROC) curves were constructed to assess the diagnostic performance of the SL gap distance in identifying simulated ligament tears. RESULTS: There were no significant differences between stages in the static SL gap distance. Dynamic SL gap distance increased significantly following SL interosseous ligament (SLIL) sectioning. According to the ROC curve for dynamic SL gap distance, the area under the curve was 0.94 for the assessment of the diagnostic performances in identifying complete SLIL sectioning. A cut-off value of 1.4 mm for the dynamic SL gap showed the highest diagnostic accuracy rate (91%). The dynamic SL gap distance showed a high diagnostic performance in the detection of dorsal intercarpal ligament (DICL) sectioning. The highest accuracy rate (85%) was noted when the threshold value was set at 2.8 mm. CONCLUSION: The SLIL is the primary stabilizer of the SL joint in the viewpoint of arthroscopic measurement. Dynamic SL joint widening of more than 1.4 mm showed the best predictive ability for complete SLIL tears, while 2.8 mm widening made it possible to predict both DICL and SLIL tears.

Arthroscopic surgery of the middle carpal joint in trotting Standardbreds: findings and outcome.

OBJECTIVES: To describe the injuries in the middle carpal joint of trotting Standardbred racehorses in relation to future racing and to review the use of synovectomy in clinical cases. METHODS: Review of medical records and racing statistics of clinical cases. RESULTS: Sixty-six percent of horses undergoing arthroscopic surgery of the middle carpal joints returned to racing, but there were only weak associations between future racing success and findings at surgery. Lesions in the middle carpal joint were similar to what have previously been described, but there were no recorded injuries to the intermediate carpal bone in the horses in this sample population. CLINICAL RELEVANCE: Making an accurate prognosis for return to racing based on the findings in the middle carpal joint at the time of surgery appears to be difficult.

Chronic perilunate dislocations treated with open reduction and internal fixation: results of medium-term follow-up.

The purpose of this study was to evaluate the medium-term follow-up results of a series of ten perilunate dislocations treated operatively at least three weeks following injury. The intervals from injury to treatment of the delayed and the chronic groups were four weeks (range, three to six weeks) and 17 weeks (range, 11-25 weeks), respectively. The average follow-up time was 90 months. Surgical procedures included open reduction, internal fixation, grafting, ligament repair, and external fixation. Clinical function was evaluated by the Cooney clinical scoring system. The radiological assessment included the radiolunate angle, scapholunate angle, the revised carpal height ratio, and presence or absence of midcarpal arthritis. In the delayed group, there were two excellent, one good and one poor results. The average postoperative clinical score was 81 (good). In the chronic group, there were four good, one fair, and one poor results. At the last follow-up, the average postoperative clinical score was 76.7 (good). Our results indicate that open reduction and internal fixation can be applied in the treatment of delayed and some of the chronic perilunate dislocations and achieve satisfactory results.

Current Techniques in Scapholunate Ligament Reconstruction.

Scapholunate ligament injuries are common and can lead to a predictable pattern of arthritis (scaphoid lunate advanced collapse wrist) if unrecognized or untreated. This article describes the relevant anatomy, biomechanics, and classification system, and provides an up-to-date literature-based review of treatment options, including acute repair and various reconstruction techniques. It also helps guide surgeons in making decisions regarding a systematic treatment algorithm for these injuries.

A dislocation of the carpal-metacarpal joints of the index, middle and ring finger.

A dislocation of the carpal-metacarpal joints of the index, middle and ring finger is reported. This dislocation is not very common and can easily be missed without the right diagnostics. The lesion was treated by reduction and immobilization for four weeks. Two months after the trauma, the patient had regained full function of his hand.

Dynamic biomechanical evaluation of the dorsal intercarpal ligament repair for scapholunate instability.

PURPOSE: A variety of soft tissue surgical procedures have been developed for treatment of scapholunate dissociation. One reconstruction method, using the dorsal intercarpal ligament, has been used clinically with some success. The purpose of this study was to evaluate biomechanically use of the dorsal intercarpal ligament for static scapholunate dissociation. METHODS: Eight cadaver wrists were tested in a wrist joint motion simulator. Each wrist was moved in continuous cycles of flexion-extension and radial-ulnar deviation. Kinematic data for the scaphoid and lunate were recorded for each wrist in the intact state, after the scapholunate interosseous, dorsal radiocarpal, and dorsal intercarpal ligaments were sectioned, and after reconstruction using the dorsal intercarpal ligament. RESULTS: Ligamentous sectioning resulted in static scapholunate dissociation. Visually, the repair initially reduced the gap between the scaphoid and lunate, but within a few cycles of wrist motion, there were statistically significant increases in scaphoid flexion, scaphoid ulnar deviation, and lunate extension. In 6 arms, gapping between the scaphoid and lunate was observed. In 2 arms, a gap occurred and the repair also pulled out of the bone junction. CONCLUSIONS: This study does not support the hypothesis that the dorsal intercarpal ligament repair alone will stabilize the scaphoid and lunate after scapholunate instability in the immediate postoperative period.

New method of fixation in above-wrist replantation in patient with traumatic total carpal loss--a case report.

The incidence of above-wrist replantations is decreasing, mainly due to better working conditions and increased safety precautions. Osteosynthesis with a plate or external fixator is usually regarded as the gold standard of fixation. We present an unusual case of intramedulary fixation of both forearm bones to the 2nd and the 5th metacarpal bone in the case of a patient with total carpal loss. This kind of fixation gives a satisfactory result with virtually no limitation of pronation and supination movements of the wrist.