Isolated injuries to the dorsoradial capsule of the thumb metacarpophalangeal joint

Acute Thumb and Finger Instability

“…They also postulated dorsoradial tears were more frequent because with the thumb in fl exion (thumb in palm almost), an ulnar directed force was more likely since the radial directed force would be blocked by the 4 fi ngers. Hence the dorso-radial corner was most affected, it also being the weakest point [ 50 ]. They also postulated that attenuation and tearing of the capsule affected the EPL tendon hence active extension.…”

“…Pain over the dorsum of the MCPJ is the primary complaint with lack of full active extension of the proximal phalanx a close second [ 50 ]. The pain may be present for up to a year or more.…”

“…Krause in their series of 11 cases succeeded in treating 4 patients with splinting alone but none of them had subluxation or extensor lag [ 50 ]. We would reduce the joint closed, assess the collaterals before holding it in extension with a fi ne 1.0 mm Kirschner wire.…”

“…The main features to look out for are the subluxation and lack of full active extension, which go hand in hand and signal a likely surgical treatment. Krause et al reasoned that isolated capsular tears occurred in those with more fl exible thumbs , in that the longer collateral ligaments allowed for more stretch and ultimate failure of the capsule [ 50 ]. They also postulated dorsoradial tears were more frequent because with the thumb in fl exion (thumb in palm almost), an ulnar directed force was more likely since the radial directed force would be blocked by the 4 fi ngers.…”

“…They also postulated that attenuation and tearing of the capsule affected the EPL tendon hence active extension. Therefore a lack of full active extension meant surgical exploration and repair were essential [ 50 ].…”