The capitohamate ligaments. A comparison of biomechanical properties

Mid-term outcomes of three commonly used surgical reconstructions for scapholunate instability

This retrospective analysis reports the mid-term (>2 years) outcomes of capsulodesis, (modified) Brunelli tenodesis and bone-ligament-bone reconstruction for scapholunate ligament instability. In total, 60 patients (64 wrists) returned the Patient-Rated Wrist Evaluation and Disabilities of the Arm, Shoulder, and Hand questionnaires. Of these participants, 42 (46 wrists) returned for a wrist examination and radiographs. In the questionnaire group, the mean follow-up for capsulodesis was 11.8 years, tenodesis 5.9 years and bone-ligament-bone 8.9 years. In the objective outcomes group, the mean follow-up was 10.2 years for capsulodesis, 5.7 for tenodesis and 8.9 for bone-ligament-bone. In all groups, some patients showed radiographic deterioration, which did not always correlate with poor functional outcome. With a mean follow-up greater than 5 years, there was no substantial difference in clinical outcomes and patient-based outcome questionnaires between capsulodesis, tenodesis or bone-ligament-bone reconstruction for the treatment of scapholunate instability. This study emphasizes the need for further research. Surgeons should use the technique that produces the fewest complications.Level of evidence III.

3D-planned corrective osteotomy of metacarpal arch disruption after Motec® wrist prosthesis

We report two cases of metacarpal arch disruption after Motec® total wrist arthroplasty, with hyperextension of the third metacarpal and dorsal protrusion of the head. Correction osteotomies of the adjacent metacarpals using preoperative 3D surgical planning were successful. This report seeks to shed light on the origin of this deformation and to recommend some operative precautions. It is important that surgeons should be aware of the existence of this complication, as disruption of the transverse metacarpal arch affects both grasp and hand esthetics. LEVEL OF EVIDENCE: IV.

Outcomes after Bone-Ligament-Bone Intercarpal Ligament Reconstruction

BACKGROUND

Numerous surgical reconstructive techniques have been described for chronic scapholunate and lunotriquetral interosseous ligament instability.

METHODS

The authors retrospectively reviewed 16 consecutive patients who underwent bone-ligament-bone reconstruction for scapholunate or lunotriquetral intraosseous ligament predynamic and dynamic instability at a single tertiary care institution from 2013 to 2019. Clinical and radiographic outcomes, and complications, were recorded.

RESULTS

Eleven patients had bone-ligament-bone reconstruction for scapholunate ligament injury and five for lunotriquetral instability. Fourteen patients (87.5 percent) underwent diagnostic arthroscopy before bone-ligament-bone reconstruction, with nine of 14 having grade 3 and four of 14 having grade 4 injury. Capitohamate bone-ligament-bone grafts were used in nine patients (56 percent) and the graft was taken from Lister tubercle in seven (44 percent). The average age at surgery was 37 years. The average follow-up was 60.6 weeks. There were no significant differences between preoperative and postoperative radiographic parameters. Median postoperative wrist flexion was 45 degrees, and mean postoperative wrist extension was 53 degrees, which were significantly less than contralateral flexion (85 degrees; p < 0.0001) and extension (78 degrees; p < 0.0001). Thirty-eight percent of patients complained of persistent pain at final follow-up, and two patients (13 percent) underwent salvage procedures, both at approximately 6.5 months after the index reconstruction.

CONCLUSION

Short-term outcomes of bone-ligament-bone reconstruction for early-stage scapholunate and lunotriquetral ligament injuries reveal many patients with residual postoperative wrist pain and disability, and almost uniform limitations in flexion-extension motion.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, IV.

Reconstruction of the Scapholunate Ligament Using Capitohamate Bone-Ligament-Bone

Background The biomechanical properties of the capitohamate (CH) ligament are equivalent to those of the scapholunate (SL) interosseous ligament. We reconstructed the SL ligament using the CH bone-ligament-bone substitute for chronic injury of the SL ligament. Patients and Methods Beginning in 2008, 15 wrists of 14 patients with an average age of 38 years underwent this procedure with a minimum follow-up of 2 years. Thirteen wrists had an SL joint gap more than 3 mm, and two had a complete SL ligament disruption with a severe dorsal intercalated segment instability (DISI) deformity. Kirschner wires (K-wires) were removed 8 weeks after the surgery, then active ROM exercise began. Pain (on visual analog scale [VAS]), wrist motion (angle), radiographic characteristics, such as SL gap (mm) and SL angle, and Modified Mayo Wrist Score (MMWS) were evaluated. Technique The SL joint was reduced by manipulation or with the use of joysticks, then temporary fixed with K-wires. A dorsal trough was then made between the scaphoid and the lunate. The proximal half of the CH ligament was harvested with attached bone from the capitate and hamate (CH bone-ligament-bone), inset into the SL trough, and fixed firmly with 1.2-mm diameter titanium screws in the scaphoid and lunate, respectively. Results The VAS improved from 77 preoperatively to 12 postoperatively. The average wrist extension/flexion was 74°/60°. There was no ossification of the reconstructed SL at the final follow-up. The SL gap improved from an average of 4.8 mm to an average of 2.1 mm, and the SL angle changed from 67° to 55°. The MMWS improved to 82 points postoperatively from a preoperative average of 47 with eight excellent, five good, and two fair results.

Outcomes of Capitohamate Bone-Ligament-Bone Grafts for Scapholunate Injury

Purpose In an attempt to restore natural carpal kinematics more closely, bone-ligament-bone (BLB) grafts have been described for treating scapholunate (SL) injury. In this article we report the long-term results of capitohamate BLB autograft for the treatment of SL dissociation. Methods The medical records of patients treated with capitohamate BLB grafts for SL dissociation were retrospectively reviewed. Twenty-three patients were available for evaluation. Patients were sent a Disabilities of the Arm, Shoulder, and Hand (DASH) and a Patient-Rated Wrist Evaluation (PRWE) questionnaire and returned for exam. Thirteen patients returned the questionnaire, and 12 wrists were examined. Range of motion, grip strength, pain, complications, return to work, and radiographic parameters were documented. Results The average length of follow-up evaluation was 9.2 years. The average SL gap was 4.5 mm preoperatively and 3.6 mm at final follow-up. The average SL angle was 70 degrees preoperatively and 73 degrees at final follow-up. There was no statistically significant difference in preoperative versus postoperative flexion, extension, radial deviation, ulnar deviation, or grip strength. The average postoperative visual analog scale (VAS) score was 1.25 at rest and 3.58 with activity. The average Mayo Wrist Score was 66.8 preoperatively and 70.9 postoperatively (p = 0.158). The average postoperative PRWE was 20.5, and average postoperative DASH was 15.1. At final follow-up, four patients had no radiographic evidence of arthritis. Two patients had evidence of early-stage radiocarpal arthritis, four had evidence of midcarpal arthritis, and two had radiographic evidence of mild scaphotrapeziotrapezoid arthritis. One patient required a salvage procedure with four-corner fusion. Discussion BLB reconstruction can be used to treat SL instability. At final follow-up, the majority of patients did not worsen clinically or functionally or require secondary salvage procedures; however, radiologic progression of arthritis was not prevented. These outcomes are comparable to midterm results of other SL reconstructive options; thus, we have abandoned this technique for other less technically demanding procedures. Level of Evidence IV.

Biomechanical comparison of the hand-based transplant used in bone-tissue-bone scapho-lunate ligament reconstruction

Although work has been published comparing the five most commonly used transplant techniques to the properties of the scapho-lunate interosseous ligament (SLIL), no study has been carried out which compares the biomechanical properties of the different bone-tissue-bone autografts to each other, using a standard methodology of testing. The hypothesis of this study was that mechanically significant differences in the material properties of commonly used bone-tissue-bone exist when compared to each other. We tested the dorsal part of the SLIL and the five most quoted transplants in the literature: capitate to trapezoid; trapezoid to second metacarpal; third metacarpal-carpal; dorsal capitate-hamate; 4-5 extensor retinaculum. For each transplant, we measured failure load, failure displacement, width, and thickness. Anova was used to compare the different results obtained and the level of significance attributed to P<0.05. Load to failure were: SLIL 94.3±42.86N; capitate to trapezoid 37.7±23.13N; trapezoid to second metacarpal 45.43±14.28N; third metacarpal-carpal 60.11±19.94N; dorsal capitate-hamate 63±25.51N; 4-5 retinaculum 15.67±10.7N. Only the dorsal capitate-hamate ligament showed to have no significant (P>0.05) difference in term of load to failure, all the others was significantly weaker (P<0.05). Previous biomechanical studies have identified the dorsal region of the SLIL as the most structurally and functionally important area of the SLIL. As a result, attention has been more specifically brought to the replacement of the dorsal portion of the SLIL. An attempt to achieve a reconstruction that reproduces more closely the SLIL has generated research on the use of bone-tissue-bone composite graft, several donor sites have been used in order to find the most similar. Our results suggest that, using a normalized method to compare the previously described grafts harvested at the wrist level, that the dorsal capitate-hamate ligament has the closest properties to the native dorsal scapho-lunate ligament.

Conformational changes in the carpus during finger trap distraction

PURPOSE

Wrist distraction is a common treatment maneuver used clinically for the reduction of distal radial fractures and midcarpal dislocations. Wrist distraction is also required during wrist arthroscopy to access the radiocarpal joint and has been used as a test for scapholunate ligament injury. However, the effect of a distraction load on the normal wrist has not been well studied. The purpose of this study was to measure the three-dimensional conformational changes of the carpal bones in the normal wrist as a result of a static distractive load.

METHODS

Using computed tomography, the dominant wrists of 14 healthy volunteers were scanned at rest and during application of 98 N of distraction. Load was applied using finger traps, and volunteers were encouraged to relax their forearm muscles and to allow distraction of the wrist. The motions of the bones in the wrist were tracked between the unloaded and loaded trial using markerless bone registration. The average displacement vector of each bone relative to the radius was calculated, as were the interbone distances for 20 bone-bone interactions. Joint separation was estimated at the radiocarpal, midcarpal, and carpometacarpal joints in the direction of loading using the radius, lunate, capitate, and third metacarpal.

RESULTS

With loading, the distance between the radius and third metacarpal increased an average of 3.3 mm +/- 3.1 in the direction of loading. This separation was primarily in the axial direction at the radiocarpal (1.0 mm +/- 1.0) and midcarpal (2.0 mm +/- 1.7) joints. There were minimal changes in the transverse direction within the distal row, although the proximal row narrowed by 0.98 mm +/- 0.7. Distraction between the radius and scaphoid (2.5 mm +/- 2.2) was 2.4 times greater than that between the radius and lunate (1.0 mm +/- 1.0).

CONCLUSIONS

Carpal distraction has a significant (p < .01) effect on the conformation of the carpus, especially at the radiocarpal and midcarpal joints. In the normal wrist, external traction causes twice as much distraction at the lunocapitate joint than at the radiolunate joint.

A three-dimensional finite element model of maximal grip loading in the human wrist

The aim of this work was to create an anatomically accurate three-dimensional finite element model of the wrist, applying subject-specific loading and quantifying the internal load transfer through the joint during maximal grip. For three subjects, representing the anatomical variation at the wrist, loading on each digit was measured during a maximal grip strength test with simultaneous motion capture. The internal metacarpophalangeal joint load was calculated using a biomechanical model. High-resolution magnetic resonance scans were acquired to quantify bone geometry. Finite element analysis was performed, with ligaments and tendons added, to calculate the internal load distribution. It was found that for the maximal grip the thumb carried the highest load, an average of 72.2 +/- 20.1 N in the neutral position. Results from the finite element model suggested that the highest regions of stress were located at the radial aspect of the carpus. Most of the load was transmitted through the radius, 87.5 per cent, as opposed to 12.5 per cent through the ulna with the wrist in a neutral position. A fully three-dimensional finite element analysis of the wrist using subject-specific anatomy and loading conditions was performed. The study emphasizes the importance of modelling a large ensemble of subjects in order to capture the spectrum of the load transfer through the wrist due to anatomical variation.

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. The complex arrangement and kinematics of the 2 rows of carpal bones allows for an enormous degree of physiologic motion, and a hierarchy of primary and secondary ligaments serves to balance an inherently unstable structure. Although 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 change. 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, degree of secondary ligamentous damage, and arthritic change.

An analysis of the constraint properties of the distal radioulnar ligament attachments to the ulna

Nine cadaver upper extremities were tested to evaluate the constraint properties of the dorsal and palmar radioulnar ligaments at their foveal and styloid attachments to the ulna. The specimens were tested by anterior and posterior displacement of the radius relative to the ulna with the forearm in pronation, supination, and neutral rotation. There were no statistically significant differences in the relative percent of constraint contribution of the styloid and foveal ligament insertions. In neutral forearm rotation total displacement after sectioning both ligament insertions tended to be larger in palmar than in dorsal displacement. A similar trend was observed with 60 degrees forearm supination. In the pronated position, however, the trend was reversed with larger total displacement in dorsal displacement.

Radial styloidectomy: a biomechanical study on stability of the wrist joint

We investigated the influence of radial styloidectomy on carpal alignment and examined translation of the wrist after sequentially increased styloidectomy of 8 cadaver wrists. The radial aspect of the scaphoid fossa of the distal radius was cut obliquely at 3, 6, and 10 mm from the radial styloid guided by real-time fluoroscopy. Radiographic analysis of the changes of carpal alignment was performed with the wrist in neutral position. Force-displacement curves from the neutral to the radioulnar and palmar-dorsal directions were obtained using a multi-axis testing machine. Results demonstrated no significant malalignment of the carpal bones after radial styloidectomy. Significantly increased radial translation (>40% reduction in stiffness), however, was observed due to the loss of radial articular contact after 6- and 10-mm radial styloidectomies. Significant ulnar and palmar carpal displacement also was noted after 6- and 10-mm radial styloidectomies, with 6 specimens demonstrating moderate ulnar and palmar translation and 2 demonstrating notable increased palmar and ulnar translations. We conclude that there is a definite risk of increased carpal instability with radial styloidectomy procedures. A styloidectomy of no more than 3 to 4 mm is recommended.

Dynamic axial carpal instability: a case report

The concept of distal carpal row dissociation is not new. It has occurred secondary to high-energy crush or blast injuries, with resultant axial dislocations of both carpal rows and metacarpals. Axial carpal sprains without disruption or dynamic axial carpal instability have not been previously described. The evaluation of this new type of carpal instability with radiographs, tomography, arthrography, and magnetic resonance imaging failed to demonstrate its etiology. Arthroscopic evaluation of the midcarpal and radiocarpal joints demonstrated a dynamic axial carpal instability with incompetence of the capitohamate and scapholunate ligaments. Stabilization of the axial instability by capitohamate arthrodesis relieved the chronic wrist pain.