[Effect of a single proximal interphalangeal Joint Fusion of the Index, Middle or Ring Finger on the Grip and Finger Force and Load Distribution in the Hand]. / Auswirkungen der Arthrodese eines einzelnen Mittelgelenkes von Zeige-, Mittel- oder Ringfinger auf Hand- und Fingerkraft sowie auf die Druckverteilung der Hand.

BACKGROUND: Due to the functional coupling of adjacent finger joints and the quadriga effect, arthrodesis of the proximal interphalangeal joint (PIPJ) can be assumed to lead to a different grip pattern resulting in altered force distribution of the hand. PATIENTS AND METHOD: Ten patients with isolated arthrodesis of the PIPJ due to posttraumatic osteoarthritis (4×PIPJ II, 4×PIPJ III, 2×PIPJ IV) were assessed 59 (17-121) months postoperatively on average. The angle of arthrodesis was assessed by radiographs. Grip force and load distribution of both hands were measured by manugraphy using 3 differently sized cylinders. Grip force was separately assessed and compared for the whole hand as well as for each of the fingers and each phalanx. RESULTS: Average total grip force of the affected hand compared to the uninjured opposite side was 74% (38-136%) for the small cylinder, 104% (68-180%) for the mid-sized cylinder and 110% (69%-240%) for the large cylinder. Arthrodesis of the PIPJ of the index finger led to a reduction of the grip force (91%) for the small cylinder, but increased grip force for the mid-sized (120%) and large cylinder (139%). Grip force was reduced for all cylinder sizes by arthrodesis of the PIPJ of the middle finger (56%, 88% and 91%). Arthrodesis of the PIPJ of the ring finger resulted in a grip force of 76%, 105% and 91%, respectively, for the different cylinder sizes.The finger force of the affected finger was reduced after arthrodesis of the PIPJ, with the exception of the index finger, which was stronger than the unaffected opposite finger when using the large cylinder. The force of the healthy fingers on the affected side was greater when compared with the same finger on the opposite side, which led to increased grip force for the mid-sized and the large cylinder of the affected hand. A reduction in load distribution was measured mostly for the middle phalanx but also for the distal phalanx of the operated-on finger. CONCLUSION: Arthrodesis of the PIPJ almost always led to force reduction in the middle and distal phalanx of the affected finger. However, the total grip force of the hand was compensated by a higher force of the adjacent healthy fingers. In many cases, total grip force was even higher on the affected side. However, arthrodesis of the PIPJ resulted in a noticeable force reduction when smaller objects were gripped.

[Effect of distal interphalangeal joint fusion of the index or middle finger on the grip or finger force and load distribution in the hand]. / Auswirkungen der Versteifung des Zeige- bzw. Mittelfingerendgelenkes auf Hand- und Fingerkraft sowie auf die Druckverteilung.

BACKGROUND: Due to the functional coupling of adjacent finger joints and the quadriga effect of the flexor digitorum profundus an influence of the grip pattern of the hand after fusion of a distal interphalangeal joint (DIPJ) is assumed. PATIENTS AND METHODS: Two patients with DIPJ II- fusion and 8 patients with DIPJ III- fusion due to a posttraumatic osteoarthritis, but without any other pathology of both hands were assessed on average 55 (17-121) months postoperatively by manugraphy. Using three sizes of cylinders the total grip force and the load distribution of the hand and each finger were measured. The grip pattern was analyzed by 2D-graphs. The results of the affected hand were compared to the healthy opposite side. The consolidation of the DIPJ arthrodesis was confirmed and the angle of the joint fusion measured by radiographs. Patients rated their pain in rest or under strain by a visual analogue scale. RESULTS: The total grip force of the affected hand compared to the opposite side was 93 % for the small cylinder, 97 % for the middle, and 96 % for the large cylinder. Both patients with a DIPJ II- fusion neglected the index finger considerably and had a remarkably weak grip force (68/62/68 % for the 3 cylinders respectively). The grip pattern of all fingers has changed. Eight patients with DIPJ III- fusion averaged 99/106/103 % grip force. In six of them, the affected hand was stronger than the opposite hand when using the middle cylinder. The finger force of the middle and ring finger was reduced, but of the index and little finger increased. Five patients had a striking peak of local pressure at the fused DIPJ III.The angle of the fused DIPJ averaged 6° (0-21°) for all patients. Pain was rated on average 1.4 (0-5) at rest and 2 (0-8) with strain. Both aspects were not found to influence the grip force or the load distribution. CONCLUSION: After DIPJ- fusion of the middle finger its finger force is reduced; but, the total grip force is compensated by an increased finger force of the index and little finger. Despite limitations due to the small number of patients, a DIPJ II- fusion might have a considerable effect on grip force and load distribution of the hand rather due to omitting this finger than purely biomechanical effects.

The Effect of Midcarpal Versus Total Wrist Fusion on the Hand's Load Distribution During Gripping.

PURPOSE: To analyze the total grip force and load distribution of the hand with midcarpal fusion (MCF) and total wrist fusion (TWF). METHODS: Twelve patients with unilateral TWF and 12 patients with unilateral MCF were assessed at an average 64 months (range, 19-100 months) postoperatively. The total grip force and load distribution of both hands were measured by the Manugraphy system using 3 cylinder sizes. The load applied to 7 anatomical areas of the hand during cylinder grip was analyzed, comparing the operated and the nonsurgical hands. RESULTS: For the 100 mm and 150 mm cylinders, a significantly lower total grip force was found in hands operated with either TWF or MCF. For the 200 mm cylinder, there was a significant difference between nonsurgical hands and those with MCF but not between nonsurgical hands and those with TWF. For the 100 mm cylinder, the difference between nonsurgical and operated hands was greater in hands with TWF than those with MCF. For the load distribution of the hand, no differences between the operated and the nonsurgical hand were found for either MCF or TWF. CONCLUSIONS: MFC and TWF resulted in a reduced cylinder grip force. With respect to the load distribution, neither procedure influenced the relative contribution that each area of the hand produced during cylinder grip. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic III.