summary Sagittal Band Ruptures lead to dislocation of the extensor tendons and may be caused by trauma or by a chronic inflammatory process such as rheumatoid arthritis. Diagnosis is made clinically with the inability to initiate MCP extension but the ability to hold MCP in extension once passively extended. Treatment of acute traumatic injuries is generally splinting where chronic injuries often require surgical reconstruction. Epidemiology Demographics more common in pugilists index and middle finger in professionals ring and little finger in amateurs Anatomic location the middle finger is most commonly involved index 14% middle 48% ring 7% little 31% the radial SB is more commonly involved radial:ulnar = 9:1 Etiology Mechanism traumatic forceful resisted flexion or extension laceration of extensor hood direct blow to MCP joint atraumatic inflammatory (e.g. rheumatoid arthritis) spontaneously during routine activities Associated conditions MCP joint collateral ligament injuries Anatomy Extensor mechanism comprises tendons EDC/EIP/EDM lumbricals interossei retinacular system sagittal bands login to view 5 more bullets retinacular ligaments triangular ligament Sagittal band function the SB is the primary stabilizer of the extensor tendon at the MCP joint login to view 1 more bullet resists ulnar deviation of the tendon, especially during MCP flexion prevents tendon bowstringing during MCP joint hyperextension biomechanics ulnar sagittal band login to view 1 more bullet radial sagittal band login to view 3 more bullets extensor tendon login to view 5 more bullets Classification Rayan and Murray Classification Type I Sagittal band injury without extensor tendon instability Type II Sagittal band injury with tendon subluxation Type III Sagittal band injury with tendon dislocation Presentation Symptoms pain MCP soreness swelling focal MCP swelling or tenderness snapping senstion with extension Physical exam tendon snapping ulnar deviation of the digits at the MCP joint (rheumatoid arthritis) inability to initiate extension can hold MCP in extension once placed there unable to extend finger from flexed MCP position (causes tendon to subluxate) pseudo-triggering - key to recognize to avoid unnecessary trigger release surgery this is the snapping that takes place from subluxation and relocation extensor tendon dislocation into intermetacarpal gully most unstable during MCP flexion with wrist flexed least unstable during MCP flexion with wrist extended provocative test pain when extending MCP joint against resistance (with both IP joints extended) Imaging Radiographs required views hand PA, lateral, oblique optional view Brewerton view login to view 1 more bullet stress view login to view 1 more bullet findings exclude mechanical/bony pathology limiting extension, or predisposing to sagittal band rupture may show dropped fingers and ulnar deviation in rheumatoid arthritis Ultrasound (dynamic) indications when swelling obscures the physical exam findings subluxation of EDC tendon relative to metacarpal head on MCP flexion MRI indications to establish diagnosis of SB disruption (radial or ulnar SB) may show underlying etiology e.g. synovitis in rheumatoid arthritis views axial images at the level of the long MCP with MCP joint flexed for maximum EDC tendon displacement findings poor definition, focal discontinuity and focal thickening in acute injury subluxation of extensor tendon in radial direction due ulnar SB defect dislocation of extensor tendon into ulnar intermetacarpal gully radial SB defect Differentials Digital collateral ligament injury EDC tendon rupture Trigger finger Junctura tendinum disruption Congenital sagittal band deficiency MCP joint arthritis Treatment Nonoperative extension splint or yoke splint for 4-6 weeks indications login to view 1 more bullet Operative direct repair (Kettlekamp) indications login to view 2 more bullets extensor centralization procedure (realignment) indications login to view 2 more bullets Techniques Extensor Centralization Procedures (Realignment) anesthsia local approach dorsal incision reconstruction (various techniques described) trapdoor flap login to view 3 more bullets Kilgore tendon slip login to view 3 more bullets Carroll tendon slip login to view 3 more bullets McCoy tendon slip login to view 3 more bullets Watson EDC tendon transfer login to view 3 more bullets Wheeldon junctural reinforcement login to view 3 more bullets fascial strips or free tendon graft rehabilitation 0-4 weeks login to view 1 more bullet 2 weeks login to view 1 more bullet 4-8 weeks login to view 1 more bullet Complications MCP flexion contracture usually from non-operative treatment or delayed presentation secondarily intrinsic tightness develops