Wrist Orthopaedic Test: Scapholunate Ligament

The scapholunate ligament is a strong band of connective tissue that runs between the scaphoid and lunate bones in the wrist. It is one of the most important ligaments that stabilize the wrist and is essential for normal wrist function. The scapholunate ligament prevents excessive motion between the scaphoid and lunate bones and helps to transmit force between the two bones during wrist movements.

The scapholunate ligament is divided into three parts: the dorsal, proximal, and palmar portions. The dorsal and proximal portions are the strongest and provide the greatest stability to the wrist joint. The palmar portion is the weakest and is often the first to fail in cases of scapholunate ligament injury.

The scapholunate ligament cannot be tested directly through a physical examination, but there are several maneuvers that can be used to assess the stability of the ligament and evaluate for potential injury. Here are two common tests that are used to assess scapholunate ligament instability:

1. Watson Scaphoid Shift Test: This test assesses for instability between the scaphoid and lunate bones. The patient's wrist is held in ulnar deviation while pressure is applied to the scaphoid tubercle in a volar-to-dorsal direction. The examiner observes for any dorsal subluxation of the scaphoid bone relative to the lunate bone.
2. Scapholunate Ballottement Test: This test assesses for increased space or "clunking" between the scaphoid and lunate bones, which may indicate scapholunate ligament injury. The examiner grasps the patient's distal radius and ulna with one hand and the patient's hand with the other hand. The examiner then applies a downward force to the scaphoid bone while moving the wrist from radial to ulnar deviation. The examiner observes for any increased space or "clunking" between the scaphoid and lunate bones.

The sensitivity and specificity of the Scapholunate Shift Test and the Scapholunate Ballottement Test for diagnosing scapholunate ligament injury vary widely depending on the study and the population being tested.

One systematic review of diagnostic accuracy studies found that the sensitivity of the Scapholunate Shift Test ranged from 16% to 100%, with an average sensitivity of 72%. The specificity of the test ranged from 75% to 100%, with an average specificity of 96%.

Similarly, the same systematic review found that the sensitivity of the Scapholunate Ballottement Test ranged from 7% to 100%, with an average sensitivity of 52%. The specificity of the test ranged from 69% to 100%, with an average specificity of 90%.

References:

1. Berger RA. The anatomy of the ligaments of the wrist and distal radioulnar joints. Clin Orthop Relat Res. 2001;383:32-40. doi: 10.1097/00003086-200103000-00006.
2. Watson HK, Ryu J. Evolution of arthritis of the wrist. J Hand Surg Am. 1986;11(2):202-215. doi: 10.1016/s0363-5023(86)80085-6.
3. Kim JP, Chung KC. Current concepts of scapholunate ligament injury: management and controversies. Clin Plast Surg. 2014;41(2):261-277. doi: 10.1016/j.cps.2013.12.011.
4. Kwon BC, Kwon YW, Kim JP, Chung SW. Clinical and radiological results of early arthroscopic repair for acute scapholunate ligament injuries. J Hand Surg Eur Vol. 2015;40(4):365-371. doi: 10.1177/1753193414556903.
5. Bhatia S, Frank RM, Ghodadra NS, et al. The outcomes and surgical techniques of the scapholunate ligament repair and reconstruction: a systematic review. Hand (N Y). 2012;7(3):242-250. doi: 10.1007/s11552-012-9422-2.