In vivo length changes of wrist ligaments at full wrist extension

Can a structured home-based rehabilitation program reduce dorsal central wrist pain?

OBJECTIVES

Dorsal central wrist pain, often a consequence of peri-scapholunate ligament injury, can result in a decline in functional performance. There is a scarcity of clinical data evaluating the effectiveness of conservative management on peri-scapholunate ligament injury. Conservative management includes education, immobilization with orthotic devices, scapholunate-stabilizing muscle strengthening, and proprioception training. The identification of the ligamento-muscular reflex and scapholunate-stabilizing muscles formed the rationale for a rehabilitation training program. We have devised an innovative standardized 16-week treatment program for patients with dorsal central wrist pain associated with acute peri-SL ligament injury. We hypothesized that the program can effectively reduce dorsal wrist pain and improve functional performance.

MATERIALS AND METHODS

Recruited subjects underwent the 16-week home-based program, which included immobilization and rehabilitation exercises, to improve their wrist stability. Follow-up was arranged every 4 weeks for progress monitoring. The Short-Form 12 item questionnaire version 2, power grip, pinch grip, wrist range of motion, total performance score and total pain score when performing activities of daily living were used to evaluate the effectiveness of the program. An exercise adherence questionnaire was used to evaluate adherence to the home rehabilitation program.

RESULTS

Twenty-three subjects (26 wrists) completed the program. Pain on visual analog scale improved by 5.1 cm and total pain score improved from 14.4/20 to 19.5/20. Total performance score reached 39/40, which indicated near-normal wrist function. Power grip and pinch grip increased by 22.3% and 17.8%, respectively. The physical component scale of the Short-Form 12 item questionnaire showed significant improvement, while the mental component scale did not. Overall adherence was fair.

DISCUSSION

Conservative management, including immobilization and rehabilitation training, can provide significant clinical improvement in patients with dorsal central wrist pain associated with acute peri-scapholunate ligament injury.

CONCLUSION

Standardized wrist rehabilitation can be taken as a reference treatment modality. It is an evidence-based non-invasive treatment option for clinicians and therapists.

Motion of the distal radioulnar joint in extension and flexion of the wrist using axial CT imaging of healthy volunteers

BACKGROUND

The midcarpal joint and the radiocarpal joint contribute to the extension and flexion of the wrist. Little is known about the contribution of the distal radioulnar joint (DRUJ) to the extension and flexion of the wrist. This study evaluated the ulnar motion in extension and flexion of the wrist using computed tomography (CT) imaging.

METHODS

A total of 30 wrists of healthy volunteers were enrolled. CT images of the axial sections of the DRUJ were obtained with 3 different positions of the wrist: 0° of extension (straight position), maximum active extension, and maximum active flexion. Each wrist motion was performed with 3 different forearm positions: neutral, pronation, and supination. Ulnar position at the DRUJ level was measured and ulnar position with the wrist in straight position was defined as baseline. The ulnar position was recorded as positive value when the position of the ulnar head was volar side and negative value when the position of the ulnar head was dorsal side. The difference from baseline in a position of maximum extension and flexion was evaluated.

RESULTS

In forearm neutral position and pronation, a value of ulnar position in maximum wrist flexion is significantly negative compared to that in the wrist straight position: the ulnar head moved dorsally from the wrist straight position to wrist flexion. In forearm supination, a value of ulnar position in maximum wrist extension is significantly positive compared to that in the wrist straight position: the ulnar head moved to the volar side from the wrist straight position to wrist extension.

CONCLUSIONS

The ulnar head moves during extension and flexion of the wrist. The direction of the ulnar motion was different according to the wrist and forearm position.

"Hockey wrist:" dorsal ulnotriquetral ligament injury

BACKGROUND

Ulnar-sided wrist pain at the dorsal proximal triquetrum, especially during wrist pronation, flexion and radial deviation, is common in athletes, particularly ice hockey players. The purpose of this study was to evaluate in which position the dorsal ulnotriquetral ligament (DUTL) is placed under the greatest strain, the torque to failure and the injury pattern. We hypothesized that the DUTL is maximally strained with wrist flexion, pronation and radial deviation, and that, at failure, the ligament tears off the triquetrum.

METHODS

We performed a biomechanical study on 7 fresh frozen cadaveric upper extremities, with testing done on a wrist-movement stimulator to identify the position (45° of wrist flexion, 45° of wrist extension or neutral) that generated the highest and earliest strain increases in the DUTL. We performed load-to-failure testing, characterized the ligament's pattern of failure, and repaired and retested the DUTL using the same load-to-failure protocol.

RESULTS

The DUTL reached 3 N∙m the earliest in 45° of wrist flexion (p = 0.02). The native DUTL failed at 0.35 N∙m (standard deviation [SD] 0.13 N∙m) per degree of angular stiffness, 12.93 N∙m of yield strength and with angular deformation of 57.73° (SD 20.62°). There was no significant difference in these variables between the native and repaired DUTL. Tearing occurred at a mean of 10 mm (SD 2 mm) proximal from the triquetrum's insertion in a transverse midsubstance pattern.

CONCLUSION

This study showed a reproducible pattern of injury to the DUTL in a cadaveric model. Additional work is needed to further characterize the pathoanatomy of "hockey wrist."

Length Changes in Scapholunate Interosseous Ligament With Resisted Wrist Radial and Ulnar Inclination

PURPOSE

To investigate the changes in length of the scapholunate interosseous ligament (SLIL) when the wrist is resisting horizontal lateral load and the forearm is in full pronation in vivo.

METHODS

We obtained computed tomography scans of the wrists of 6 volunteers in 3 situations: 0° position (0° extension and 0° ulnar inclination) and full forearm pronation without force, and in the same position but with resisted ulnar and radial deviation. Nine zones of 3 subregions of the SLIL were measured and analyzed with computer modeling.

RESULTS

Changes in length of the palmar SLIL with resisted ulnar deviation were significantly greater than those without an applied lateral load. In contrast, the changes in length of the dorsal SLIL with resisted radial deviation were statistically greater than those in the 0° position without loading. However, no significant differences in the changes in length of the proximal SLIL were found in any of 3 situations, except the dorsal zone with resisted radial deviation.

CONCLUSIONS

Application of lateral load has an effect on the separation of the palmar and dorsal insertions of the SLIL. The palmar subregion of the SLIL was more highly strained with wrist-resisted ulnar deviation. Conversely, the dorsal subregion of the SLIL was under greater tension with wrist-resisted radial deviation.

CLINICAL RELEVANCE

For patients undergoing nonsurgical treatment of SLIL tears, a sudden contraction of ulnar or radial deviation agonist muscles may be harmful and contribute to SL instability.

In vivo metacarpophalanageal joint collateral ligament length changes during flexion

We investigated the in vivo length changes of the collateral ligaments of metacarpophalangeal joint during flexion. We obtained computed tomography scans of index, middle, ring and little fingers at 0°, 30°, 60° and 90° of joint flexion from six hands of six healthy adult volunteers. Three of them had their dominant right hand studied, and the other three had their non-dominant left hand studied. We measured and analysed the radial and ulnar collateral ligaments of each metacarpophalangeal joint from the reconstructed images. We found that the dorsal and middle portions of the both radial and ulnar collateral ligament lengthened progressively during digital flexion and reached the maximum at 90° flexion. The length of the volar portion increased from 0° to 30° flexion and then decreased from 30° to 60° flexion, reaching the minimum at 90°. In conclusion, three portions of collateral ligaments on both sides of the metacarpophalangeal joint have variable length changes during flexion, which act to stabilize the joint through its flexion arc.

Early controlled mobilization using dart-throwing motion with a twist for the conservative management of an intra-articular distal radius fracture and scapholunate ligament injury: A case report

This case describes an early controlled mobilization (ECM) approach that uses dart-throwing motion (DTM) with a twist orthoses as an alternative to immobilization for conservative management of a minimally displaced and intra-articular distal radius styloid fracture with an associated scapholunate ligament injury in a 47-year-old female health care administrator (JP). Pain-free active DTM began at day 10 (5 times/d) with a dynamic DTM with a twist orthosis worn during the day from weeks 3 to 6. At 6 weeks, JP had pain-free functional mobility and strength with minimal limitation in household and occupational activities, returning to her normal sporting activities by 3 months. ECM led to rapid return of normal functioning in the short term with no apparent impact on intermediate outcomes at 8 months. This case allows hand therapists to consider a similar ECM approach for the management of similar injuries in their patients.

LEVEL OF EVIDENCE

Level 5 and case report.

Anticipatory and Reactive Response to Falls: Muscle Synergy Activation of Forearm Muscles

We investigated the surface electromyogram response of six forearm muscles to falls onto the outstretched hand. The extensor carpi radialis longus, extensor carpi radialis brevis, extensor carpi ulnaris, abductor pollicis longus, flexor carpi radialis and flexor carpi ulnaris muscles were sampled from eight volunteers who underwent ten self-initiated falls. All muscles initiated prior to impact. Co-contraction is the most obvious surface electromyogram feature. The predominant response is in the radial deviators. The surface electromyogram timing we recorded would appear to be a complex anticipatory response to falling modified by the effect on the forearm muscles following impact. The mitigation of the force of impact is probably more importantly through shoulder abduction and extension and elbow flexion rather than action of the forearm muscles.

How does wrist position affect the length of the distal radioulnar ligament: a three-dimensional image study in vivo?

PURPOSE

This study was designed to investigate the length changes of the distal radioulnar ligament at different wrist positions and to determine the effect of hyperextension on the distal radioulnar ligament and to find out the most vulnerable position where the distal radioulnar ligament rupture and foveal avulsion.

METHODS

We obtained computed tomography scans of the wrists for 12 volunteers including two groups: hyperextension group and hyperextension with maximal rotation group. The images were reconstructed to the three-dimensional bone structures with customized software. The four portions of the distal radioulnar ligament were measured and analyzed statistically.

RESULTS

No significant differences were noted in the lengths of the each portion of the distal radioulnar ligament among neutral position, wrist hyperextension, and hyper-radial extension. From neutral position to hyperextension with maximal pronation, the lengths of the palmar superficial radioulnar ligament (psRU) and dorsal deep radioulnar ligament (ddRU) decreased significantly, whereas the dorsal superficial radioulnar ligaments (dsRU) and palmar deep radioulnar ligament (pdRU) increased significantly. From neutral position to hyperextension with maximal supination, the lengths of the pdRU and dsRU ligaments decreased significantly, and the lengths of psRU and ddRU ligaments changed little.

CONCLUSIONS

The factor of hyperextension has little effect on the length of the distal radioulnar ligament and the distal radioulnar ligament may be under great tension at the position of hyperextension with maximal pronation. These findings can provide more information to understand the pathomechanics of the triangular fibrocartilage complex injury caused by a fall on the outstretched hand and can provide information relevant to the distal radioulnar ligament restoration.

In Vivo length changes of the proximal interphalangeal joint proper and accessory collateral ligaments during flexion

PURPOSE

To investigate the length changes in proper collateral ligament (PCL) and accessory collateral ligament (ACL) during flexion of the proximal interphalangeal (PIP) joint in vivo and how portions of the PCL and ACL stabilize the PIP joint.

METHODS

We obtained computed tomography scans of the index, middle, and ring fingers of one hand from 6 volunteers at 0°, 30°, 60°, 90°, and full flexion of the PIP joint. Radial and ulnar PCL and ACL were measured and analyzed with computer modeling.

RESULTS

The data showed that during flexion the average length of the dorsal portion of the radial and ulnar PCL increased significantly and reached a maximum at 90°. The volar portion of the radial and ulnar PCL and the distal portion of the radial and ulnar ACL shortened continuously from extension to full flexion.

CONCLUSIONS

The proximal and middle portions of each ACL are nearly isometric, the dorsal portion of each PCL becomes taut only in flexion, and the volar portion of PCL and the distal portion of ACL become taut only in extension. The current findings indicate that the dorsal portion of PCL is the most stabilizing structure during flexion of the PIP joint, and that the volar portion of PCL and the distal portion of ACL provide the crucial lateral stability to the joint at extension.

CLINICAL RELEVANCE

The results may provide information relevant to the ligaments of PIP joint reconstruction and rehabilitation.

Length changes of scapholunate interosseous ligament at different wrist positions: an in vivo 3-dimension image study

PURPOSE

The scapholunate interossous ligament (SLIL) has a critical role in maintaining the proper kinematic relationship between the scaphoid and the lunate. We hypothesize that the length of SLIL changes significantly at wrist full extension and during forearm rotation. The aim of this study was to investigate the length changes of SLIL at wrist full extension and forearm rotation in vivo.

METHODS

Twelve volunteers were randomly divided to two groups. We obtained computed tomography scans of the wrists at different wrist positions. The three regions of the SLIL were measured and analyzed with computer modeling.

RESULTS

The results showed that from the neutral to full extension of the wrist, the length of volar SLIL and volar, middle portions of the proximal SLIL increased significantly. The volar and proximal SLIL increased significantly in maximal forearm pronation.

CONCLUSIONS

The lengths of the volar and proximal regions of SLIL increase substantially at wrist full extension, but only slightly at maximal forearm pronation. Clinically, wrist full extension may make the SLIL ligament vulnerable to disruption.