- Metacarpals
- Hamate
- Capitate
- Trapezoid
- Trapezium
- Pisiform
- Triquetrium
- Lunate
- Scaphoid
- Ulna
- Radius
- Scaphoid is most commonly fractured carpal bone with tenuous blood supply leading to increased post-injury risks
- Lunate injury can lead to Kienbock Disease
- SL is most common form of Traumatic Carpal Instability
- SL frequently overlooked condition which are associated with TFCC tears
- Dorsal Intercalated Segment Instability (DISI)
- ScaphoLunate Advanced Collapse (SLAC)
- ScaphoLunate ligament is weaker dorsally while it is stronger volarly causing volar tilt of the scaphoid against the lunate
- Unopposed extension forces on the Lunate by Triquetrium could lead to DISI
- Abnormal Scaphoid motion and dorsal subluxation onto the radial fossa on wrist flexion lead to wrist arthritis
- Migration of capitate can lead to SLAC (on dorsiflexion or extension)
Wrist (Radiocarpal) Range of Motion
Flexion (Palmar Flexion) =80 Degrees
Extension (Dorsi Flexion) =70 Degrees
Abduction (Radial Deviation) =20 Degrees
Adduction (Ulnar Deviation) =30 Degrees
The patient should point to the most painful area and indicate where the pain radiates.
Special tests can help support specific diagnoses e.g. :
| Finkelstein’s test | Fovea sign |
| Lunotriquetral ballottement | Grind test |
| Lunotriquetral shear test | McMurray’s test |
| Pisotriquetral grind test | Piano-key test |
| Shuck test | Supination lift test |
| Ulnar snuffbox test | Watson’s test 1 & 2 |
Imaging
Radiographs
PA, Lateral, and Gripping Views should be obtained
The following items should be examined:
- Scapholunate Angle: 46◦ is Normal; > 60 degrees is abnormally elevated
- ScaphoLunate Gap: > 2mm is abnormal
- “Signet Ring” sign: as scaphoid flexes, distal pole will appear as ring on PA view
- Radiolunate Angle: >15◦ dorsal indicates DISI deformity
- Disruption of Gilula Lines
- Gripping Views may show SLIL changes
Arthrograms
- Arthrograms were initially the definitive tests, but have shown to have a very high rate of false positives and a non-negligible rate of false negatives.
- MRI has been suggested to examine wrist ligaments but rarely allow a definitive judgment to be made.
Surgical Evaluation
Arthroscopy
- Allows for direct inspection of SLIL ligament and supporting structures
- Helps determine changes in Ulnar Variance
- Helps inspect for TFCC tears
- Physical examination, though, should prevail
Acute
- Open Repair
- Pin Acute Lesions
- Cast Immobilization
Chronic (static or dynamic)
Current Techniques include:
- Dorsal capsulodesis or tenodesis:to prevent static or dynamic flexion
- Brunelli Procedure: uses a strip of flexor carpi radialis through distal scaphoid and distal radius to limit scaphoid flexion and stabilize SLIL and STIL ligaments
- Ligament Reconstruction: Attempts using bone-ligament-bone constructs from carpus, foot, and extensor retinaculum
- Arthrodesis: Scaphotrapezial or Scaphocapitate arthrodesis
Chronic (with Arthritis)
Current Techniques include:
- STT fusion with radial styloidectomy
- Scaphocapitate Fusion with radial styloidectomy
- Four Corner Fusion or Proximal Row Carpectomy
- Total Wrist Fusion
- Total Wrist Arthroplasty
- J. Liberman(ed), S. Moran, M. Rizzo, A. Shin. Chapter 50: Hand & Wrist Fractures and Disclocations, including carpal instability. AAOS Comprehensive Review. (2009 edition).
- J Hand Surg [Am]. 2009 May 29. Treatment of Traumatic Scapholunate Dissociation. Kalainov DM, Cohen MS.
- Tech Hand Up Extrem Surg. 2009 Mar;13(1):54-8. Three-corner midcarpal arthrodesis and scaphoidectomy: a simplified volar approach. Dutly-Guinand M, von Schroeder HP
- Nelson, DL: The importance of the physical examination. Hand. Clin. 1997, Feb; 13(1):13-15. PMID: 9048179
- J Hand Surg Am. 2001 Jul;26(4):749-54. Static scapholunate dissociation: a new reconstruction technique using a volar and dorsal approach in a cadaver model. Dunn MJ, Johnson C. Department of Orthopaedic Surgery, Monmouth Medical Center, Longbranch, NJ, USA.
- J Hand Surg Br. 2000 Apr;25(2):188-92. Scapholunate ligament repair using the Mitek bone anchor. Bickert B, Sauerbier M, Germann G. Department of Plastic and Hand Surgery/Burn Centre, University of Heidelberg, Ludwigshafen, Germany.
- Arthroscopy. 1993;9(1):109-13. Pull-out strength of five suture anchors. Carpenter JE, Fish DN, Huston LJ, Goldstein SA. Orthopaedic Research Laboratories, University of Michigan, Ann Arbor.
- Eplasty. 2009;9:e7. Epub 2009 Jan 29. Reduction and maintenance of scapholunate dissociation using the TwinFix screw.Opreanu RC, Baulch M, Katranji A.
