Differential onset patterns and causes of carpal tunnel syndrome after distal radius fracture: a retrospective study of 105 wrists.

BACKGROUND

It is well known that carpal tunnel syndrome (CTS) can occur in a wide range of time periods after distal radius fracture (DRF). Few studies have evaluated in detail the relationship between fracture and electrophysiological finding characteristics and time to onset of CTS after DRF. To clarify the characteristics of CTS after DRF, we classified a large number of clinical cases based on the period from the injury to onset of CTS. These cases were analyzed retrospectively.

METHODS

We reviewed 105 wrists with CTS following DRF. Patients' ages ranged from 13 to 89 years. These 105 wrists were divided into three groups according to the period of post-fracture onset of CTS. Twenty-eight wrists were classified into the acute onset group (when the symptoms of CTS occurred within 1 week after fracture). Forty-seven wrists were classified into the subacute onset group (when symptoms of CTS occurred from 1 to 12 weeks after fracture). The remaining 30 wrists were classified into the delayed onset group (when symptoms of CTS occurred more than 12 weeks after fracture). Deformity of the distal radius on X-ray films was evaluated and distal motor latency (DML) of the median nerve was recorded to compare values among these three groups.

RESULTS

In the acute onset group, 68% had an AO C-type fracture and 46% were caused by a high-energy injury. The percentage of this fracture pattern and mechanism was significantly higher in the acute onset group than in the other groups (P < 0.05; Kruskal-Wallis test). In the subacute onset and delayed onset groups, 79% and 63% had an A-type fracture and more than 90% were caused by a low-energy injury. In the delayed onset group, the incidence of prolonged DML in the contralateral wrists was 71%, which was significantly higher than in the other two onset groups (P < 0.05; Kruskal- Wallis test).

CONCLUSIONS

There were three onset patterns of CTS after DRF, and each CTS onset pattern had different etiologic mechanisms and different clinical features of CTS. In the acute onset group, a high-energy fracture pattern was associated with CTS. In the subacute and the delayed onset groups, lowenergy injury in elderly women was associated with CTS. Both deformity of the fracture and preexisting median nerve dysfunction were suggested as predisposing factor for CTS.