The Effect of Radioscapholunate Fusion with and without Distal Scaphoid and Triquetrum Excision on Capitolunate Contact Pressures

Objective: Radioscapholunate (RSL) arthrodesis has been demonstrated to be effective for patients with isolated radiocarpal arthritis. However, it has been associated with decreased ROM and midcarpal arthrosis postoperatively. To improve ROM after RSL arthrodesis, distal scaphoid excision (DSE) and triquetrum excision (TE) may be performed. Capitolunate (CL) joint forces were measured to evaluate the effect of each of these motion-improving RSL fusion modifications on the midcarpal joint.

Methods: Ten wrist specimens were dissected of all superficial soft tissue. The carpus was exposed and RSL arthrodesis was performed using plates and screws. Contact area, pressure, and force were measured in the CL joint during application of uniaxial load, using pressure sensitive film. Measurements were obtained before RSL fusion, after RSL fusion, after RSL fusion with DSE, and after RSL fusion with DSE and TE. Statistical analyses were performed using a one-way ANOVA.

Results: RSL fusion, with and without DSE, significantly increased contact forces (p < 0.03) in the CL joint from 5.05 ± 1.24 N to 7.59 ± 2.82 N and 6.87 ± 2.82 N, respectively. TE reduced CL contact forces to 6.26 ± 1.88 N. The CL contact pressures were similar between all groups (p = 0.42). Additionally, RSL fusion with or without DSE increased the CL contact area between 32% and 43%, while TE reduced CL contact area from RSL fusion to an intermediate level.

Conclusions: Motion increasing procedures performed at the time of RSL fusion may affect midcarpal joint contact force and area. These results showed that DSE increased contact forces resulting from RSL fusion, while the addition of TE reduced contact forces to an intermediate level. While the clinical significance of these findings is unknown, surgeons should take this information into consideration when counseling their patients on the possibility of developing adjacent joint arthritis in the future.