Department of Orthopaedic Surgery, Nishi-Nara Central Hospital, Nara, Japan; Department of Orthopaedic Surgery, Nara Medical University, Nara, Japan.
Department of Hand Surgery, Nara Medical University, Nara, Japan.
J Hand Surg Am. 2021 Jan;46(1):71.e1-71.e7. doi: 10.1016/j.jhsa.2020.08.009. Epub 2020 Nov 6.
Distal scaphoid and triquetrum excisions can improve the range of wrist motion after radioscapholunate (RSL) fusion, but little is known about the kinematics of dart-throwing and global circumduction motions. We hypothesized that these excisions could increase the range of motion without causing midcarpal instability.
Seven fresh-frozen cadaver upper extremities were mounted on a testing apparatus after isolation and preloading of the tendons of the flexor carpi radialis, flexor carpi ulnaris, extensor carpi radialis, and extensor carpi ulnaris. Sequential loadings of the flexor carpi ulnaris and extensor carpi radialis simulated active dart-throwing motion. Passive circumferential loading produced the wrist circumduction motion. We measured the range of wrist motions with an electromagnetic tracking system in 4 experiments: intact, simulated RSL fusion, RSL fusion with distal scaphoid excision, and RSL fusion with distal scaphoid and total triquetrum excisions. To evaluate midcarpal stability, we conducted passive mobility testing of the distal carpal row in the radial, volar, ulnar, and dorsal directions.
Radioscapholunate fusion decreased the dart-throwing motion to a mean of 46% of the baseline value; distal scaphoid and triquetrum excisions increased the mean arc to 50% and 62%, respectively. Radioscapholunate fusion diminished the wrist circumduction to a mean of 43% of the baseline value, which increased to a mean of 58% and 74% after distal scaphoid and triquetrum excision, respectively. A significant increase in radial deviation was noted after distal scaphoid excision, and subsequent triquetrum excision significantly increased motion in the ulnar-palmar direction. Regarding midcarpal stability, dorsal translation significantly increased after distal scaphoid and triquetrum excisions.
Distal scaphoid and triquetrum excision after RSL fusion improved both dart-throwing and circumduction motions, but dorsal midcarpal instability occurred.
Subsequent carpal excisions may improve short-term outcome by increasing motions in a RSL-fused wrist; however, a potential risk of midcarpal instability should be considered.
桡尺远侧关节（RSL）融合后，切除远侧舟骨和三角骨可以改善腕关节的活动范围，但对于投掷运动和全环周运动的运动学知之甚少。我们假设这些切除可以在不引起腕中关节不稳定的情况下增加活动范围。
在分离和预加载屈肌腕骨、尺侧腕屈肌、伸肌腕骨和伸肌尺侧腕骨的肌腱后，将 7 个新鲜冷冻的上肢尸体标本安装在测试装置上。尺侧腕屈肌和伸肌腕骨的连续加载模拟主动投掷运动。被动的环周加载产生腕关节的环周运动。我们使用电磁跟踪系统在 4 个实验中测量腕关节运动范围：完整、模拟 RSL 融合、RSL 融合伴远侧舟骨切除和 RSL 融合伴远侧舟骨和三角骨切除。为了评估腕中关节的稳定性，我们在桡侧、掌侧、尺侧和背侧方向对远侧腕骨排进行了被动活动度测试。
RSL 融合使投掷运动减少到基线值的 46%；切除远侧舟骨和三角骨分别使平均弧增加到 50%和 62%。RSL 融合使腕关节环周运动减少到基线值的 43%，切除远侧舟骨和三角骨后分别增加到平均 58%和 74%。切除远侧舟骨后桡侧偏斜明显增加，随后切除三角骨明显增加了掌侧-尺侧方向的运动。关于腕中关节的稳定性，切除远侧舟骨和三角骨后背侧平移明显增加。
RSL 融合后切除远侧舟骨和三角骨可改善投掷运动和环周运动，但会出现腕中关节背侧不稳定。
RSL 融合腕关节后，进行后续的腕骨切除可能会通过增加腕关节的运动来改善短期结果；然而，应考虑到腕中关节不稳定的潜在风险。
