Experimental Study Of The Biomechanical Effect Of Proximal Row Carpectomy And Limited Intercarpal Arthrodesis On The Wrist

Objective: To investigate the motion and the biomechanical change of normal wrist and the wrist after proximal row carpectomy and limited intercarpal arthrodesis.And to explore the effct of proximal row carpectomy and limited intercarpal arthrodesis on the wrist.and to provide theoretical base of the clinical treatment of the carpal disease. Method: 16 fresh-frozen human forearm specimens were used,and were divided into 4 groups randomly,each group included 4 specimens. A group: proximal row carpectomy(including lunate excision); B group: scaphoid –trapezium-trapezoid arthodesis; C group: scaphoid-triquetrum excision+capitate-lunate fusion; D group: scaphoid excision+four corner fusion. These specimens were placed on the CSS-44020 biomechanical test machine,and were drived by the strength of 100N with the speed of 5 ㎜/s to make the movement of flexion,extension,radial deviation and ulnar deviation and checked the range of the wrists.Then the pressure sensitive films were inserted into the wrists,and the wrists were pressed by 200N,with the speed of 5 ㎜/s,and persisted for 60s on the neutral position.Data collected from the films were studied. Result: ⑴The range of wrist movement: (i)the normal wrist: flexion was 74.2°±4.9°,extension was 63.3°±3.6°,radial deviation was 20.2°±3.4°,ulnar deviation was 36.8°±2.6°; (ii)lunate excision: flexion was 55.2°±5.2°, extension was 50.6°±4.5°,radial deviation was 17.8°±3.5°, ulnar deviation was 31.5°±3.4°; ( iii ) proximal row carpectomy: flexion was 48.1°±5.6°, extension was 43.6°±4.6°,radial deviation was 10.3°±4.1°, ulnar deviation was 21.0°±4.3°; (iv)scaphoid –trapezium-trapezoid arthodesis: flexion was 68.4°±5.2°, extension was 51.5°±4.6°, radial deviation was 15.7°±3.4°, ulnar deviation was 24.5°±2.3°; ( v ) scaphoid-triquetrum excision+capitate-lunate fusion: flexion was 64.5°±7.1°, extension was 60.0°±5.2°, radial deviation was 26.9°±5.2°, ulnar deviation was 42.4°±3.2°; (vi)scaphoid excision+four corner fusion: flexion was 61.9°±6.6°, extension was 54.9°±5.3°radial deviation was 17.0°±4.9°, ulnar deviation was 27.1°±3.9°⑵Data of pressure sensitive films: ①The pressed area of the wrists: (i)the normal wrist: 640.57±23.15(mm~2)(;ii)lunate excision: 254.89±22.2 ( mm~2 ) ; ( iii ) proximal row carpectomy: 81.26±2.38(mm~2); (iv)scaphoid –trapezium-trapezoid arthodesis: 265.00±8.97(mm~2); (v)scaphoid-triquetrum excision+capitate-lunate fusion: 125.81±5.97(mm~2); (vi)scaphoid excision+four corner fusion: 164.00±8.43(mm~2).②The pressure intensity of the wrist: (i)the normal wrist: 27.68±0.73(N/㎝~2); (ii)lunate excision: 47.68±2.62(N/㎝~2); (iii)proximal row carpectomy: 169.81±2.27(N/㎝~2); (iv)scaphoid –trapezium-trapezoid arthodesis: 53.87±3.07 ( N/ ㎝~2 ) ; ( v ) scaphoid-triquetrum excision+capitate-lunate fusion: 112.86±0.74(N/㎝~2); (vi)scaphoid excision+four corner fusion: 55.28±5.11(N/㎝~2).The highest pressure intensity was found in proximal row carpectomy. There are statistical significant difference between the normal wrist and any group (all P<0.05),and there also are significant difference between proximal row carpectomy and any group (all P<0.05).But no significant difference were observed between scaphoid –trapezium-trapezoid arthodesis and scaphoid excision+four corner fusion (P>0.05). Like proximal row carpectomy, the statistical significant difference were observed between scaphoid-triquetrum excision+capitate-lunate fusion and other groups. Conclusion: ⑴After the operations of lunate excision,scaphoid –trapezium-trapezoid arthodesis ,scaphoid excision+four corner fusion and scaphoid-triquetrum excision+capitate-lunate fusion, the range the movement of the wrists decreased. Proximal row carpectomy impacted on the wrist most significantly,the range of movement reduced most. Although the range the movement of the wrists decreased ,the function of wrists could satisfy the needs of daily. ⑵Under neutral position, the pressure distribution of normal wrists was extremely even. The general wrist pressure increased after lunate excision,scaphoid –trapezium-trapezoid arthodesis and...