Biomechanics of the intact and surgically repaired proximal interphalangeal joint collateral ligaments

The Collateral Ligament of the Digits of the Hand: Anatomy, Physiology, Biomechanics, Injury, and Treatment

Ligament injuries are among the most common musculoskeletal injuries seen in clinical practice and ligaments are the most frequently injured structures in a joint. Ligaments play an important role in balancing joint mobility and joint stability. Disruption of joint ligaments severely impairs joint function. Over the past 10 years, a new appreciation of a neuroanatomy and neurophysiology of joint ligaments and its biofeedback loops to surrounding muscles and tendons has emerged to explain the relationship between primary and secondary restraints that allow normal joint motion yet prevent pathological motion. This review focuses on this recent information with a view to new clinical approaches to these common problems.

Clinical outcomes of operative repair of complete rupture of the proximal interphalangeal joint collateral ligament: Comparison with non-operative treatment

Objectives

The purpose of this study was to compare the outcomes of non-operative treatment and operative repair of grade III injuries with complete rupture of the collateral ligament of the proximal interphalangeal (PIP) joint.

Patients and methods

Seventeen patients with grade III injuries with at least 6 months of follow-up were included. Seven patients underwent non-operative treatment and 10 patients underwent operative treatment. We evaluated the following clinical outcomes after treatment: 1) range of motion of the PIP and distal interphalangeal (DIP) joints, 2) joint stability, 3) pain score, and 4) amount of fusiform deformity of the PIP joint.

Results

There was no instability in the lateral stress test in either group. The ranges of motion of the PIP and DIP joints were not statistically different between the two groups at final follow-up. However, the ranges of motion recovered more quickly in the operative group than the non-operative group within the first 3 months after treatment. Patients in the operative group had less pain and better cosmetic appearance of the PIP joint.

Conclusion

Our results suggest that operative repair of the PIP collateral ligament can provide good joint stability, rapid functional recovery, and minimize fusiform deformity of the PIP joint.

Level of evidence

Level III, Therapeutic study.

Change in the collateral and accessory collateral ligament lengths of the proximal interphalangeal joint using cadaveric model three-dimensional laser scanning

The purpose of this study was to assess the lengths of the index and middle finger proximal interphalangeal joint ligaments and determine the relative changes in the collateral and accessory collateral ligament lengths at 0°, 45° and 90° flexion. We generated three-dimensional scans of 16 finger (eight index and eight middle) proximal interphalangeal joints to assess relative changes in ligament length. Significant changes were found between 45°-90° and 0°-90° for the ulnar collateral ligament of the index finger and both collateral ligaments of the middle finger between 45°-90° and 0°-90°. No significant changes in length were found for the radial collateral ligament of the index finger or the accessory collateral ligaments of the index and middle fingers. Overall, it was found that the collateral ligament length changed significantly, but there was no significant change in the accessory collateral ligaments.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

Collateral Ligament Reconstruction of the Proximal Interphalangeal Joint

Proximal interphalangeal joint collateral ligament injuries are common; however, chronic instability of this joint is rare. In such cases, however, there is no consensus on optimal management. Various repairs and reconstructions have been devised, although the literature on outcomes remains scant. We present a method of reconstruction of the proximal interphalangeal joint collateral ligament using a distally based slip of the flexor digitorum superficialis tendon.

SURGICAL REPAIR OF CENTRAL SLIP AVULSION INJURIES WITH MITEK BONE ANCHOR — RETROSPECTIVE ANALYSIS OF A CASE SERIES

The purpose of this study is to describe our technique of central slip repair using the Mitek bone anchor and to evaluate the treatment outcome. Eight digits in eight patients were reconstructed using the bone anchor: three little fingers, two middle fingers, two index fingers and one ring finger. There were two immediate and six delayed repairs (range from one day to eight months). Four patients had pre-operative intensive splinting and physiotherapy to restore passive extension of the proximal interphalangeal joint prior to central slip reconstruction. All patients have made good progress since surgery. No patient requires a second procedure and none of the bone anchors have dislodged or loosened. We conclude that the Mitek bone anchor is a reliable technique to achieve soft tissue to bone fixation in central slip avulsion injuries. We recommend that this technique be considered as a treatment option for patients requiring surgical repair.

Repair of central slip avulsions using Mitek Micro Arc bone anchors. An in vitro biomechanical assessment

In this study we evaluated the pullout strength of the Mitek Micro Arc anchor for the reconstruction of central slip avulsions at the proximal interphalangeal joint of the finger. Forty paired fresh frozen cadaver fingers were randomized into treatment (anchor) and control groups (horizontal mattress repair) and subjected to tensile loading to failure. The mean (SD) failure loads of the repairs were: Mitek repair group 22.3 (4.7) N, and control group 24.7 (5.5) N. There were no statistically significant differences between the failure loads or the failure mechanisms of the two repairs. The pullout strength of the isolated anchor-bone complex was evaluated by refitting five anchors with stainless steel wire. The mean failure load of the isolated anchor was 400% higher than the tendon-suture-anchor complex, indicating that the weakest link of the system is not the bone-anchor interface.