Study on correlation between reduction loss and fixator moment arm after treatment of acromioclavicular joint dislocation using endobutton technique / 医用生物力学

Objective To study the correlation between the amount of reduction loss and the length of fixator moment arm after treating acrmioclavicular（AC）joint dislocation with the endobutton technique as viewed from mechanics. Methods 24 patients with acute AC joint dislocation were treated with the endobutton technique and made the follow-up from Mar. 2009 to Dec. 2010 in Shanghai Ninth People’s Hospital. The loss of reduction was observed by evaluating the change of distance between the coracoid and clavicle three days and six months after the operation, respectively. Meanwhile, the length from the upper endnobutton midpoint to the proximal end of clavicle (L1) and the whole length of clavicle (L) were measured and the ratio of L1/L as the moment arm of the fixator was calculated to study the correlation between reduction loss and moment arm. Results All the 24 patients received good reduction after the operation, and the distance between the coracoid and clavicle returned to normal. The average distance between the coracoid and clavicle three days and six months after the operation was (28.2±3.9) and (29.5±4.1) mm, respectively. The amount of average reduction loss was (1.3±1.2) mm. The average moment arm was 0.79±0.03. There was a significant negative correlation between the reduction loss and moment arm with the correlation coefficient -0.498(P＜0.05). Conclusions For the treatment of AC joint dislocation using endobutton technique, the position of the endobutton is closely related with the loss of reduction postoperatively. The shorter the moment arm, the greater the loss of reduction would be. The proper moment arm should be around 0.80.

The Amount and Related Factors of Reduction Loss in Distal Radius Fracture after Treatment by Kapandji Technique

PURPOSE: To evaluate the amount and related factors of reduction loss in distal radius fracture after treatment by Kapandji technique. MATERIALS AND METHODS: From September 2004 to May 2006, 44 cases (43 patients) of distal radius fractures were treated by Kapandji technique. Fracture were classified with AO classification and volar tilt, radial inclination, and radial length were measured in preoperative, immediate, postoperative radiographs. Also the amount and related risk factors of reduction loss were analyzed. In addition, the radiological results at last follow up were evaluated using modified Lidstrom scoring system. RESULTS: There was significantly more reduction loss of volar tilt in the patients with AO type C comparing with other fracture types, but the patients who were treated using three k-wire fixations including intrafocal K-wires showed significantly more reduction loss of volar tilt also. Overall radiological results at last follow up showed that excellent was 50% in cases with dorsal comminution, but, the other cases 90%. In addition, excellent was 70% in type A cases, but, in type C 44%. CONCLUSION: Kapandji technique percutaneous pinning is the one of effective treatment options for distal radius fracture. But, type of fracture, total number of K-wires, and presence of dorsal cortical comminution showed the significant relation with postoperative reduction loss of volar tilt and overall radiological results at last follow up.

Percutaneous Vertebroplasty in the Treatment of Osteoporotic Compression Fracture (99 Patients, 171 Vertebral Bodies)

PURPOSE: This study was designed to compare the clinical and radiologic outcome of the patients who underwent percutaneous vertebroplasty among the groups based on follow-up period and BMD. MATERIALS AND METHODS: A total of 99 patients (171 vertebral bodies) underwent percutaneous vertebroplasty from January 2001 to September 2003. The patients were divided into 3 groups by follow-up periods, and also divided into 2 groups by BMD. We investigated the difference of radiologic and clinical effects among the groups. Radiologic findings was assessed as vertebral height restoration rate and rate of reduction loss by measurement of the height of vertebral body. The clinical outcomes were graded into 5. The statistical analysis was done using Chi-squire test and Independent-samples T test. RESULTS: Among the groups divided by follow-up period, there was no statistically significant difference of clinical and radiologic results except the rate of reduction loss between group I and group III (p>0.05). Between the groups divided by BMD, there was no statistically significant difference of clinical and radiologic results. CONCLUSION: Percutaneous vertebroplasty with bone cement for the osteoporotic compression fracture is an efficient procedure and considered as technique producing pleasurable clinical and radiologic results regardless of follow up-period and BMD.

Radiologic Reduction Loss after Surgical Treatment of Distal Radius Fracture

PURPOSE: To compare and analyse radiologic reduction loss between fixation with K-wire only group and fixation with K-wire and external fixator group for surgical treatment of distal radial fracture. MATERIALS AND METHOD: We analysed 60 patients who received the operative treatment with K-wire fixation only or K-wire and external fixator and also were in regular follow up at least one year. We compared radiologic reduction loss of radial length, radial inclination and volar tilt between immediate post-operative radiograph and latest follow up radiograph according to operative methods, fracture patterns and age groups. RESULTS: Reduction loss of volar tilt was greater in fixation with K-wire only group than fixation with K-wire and external fixator group (p<0.05). Reduction losses of radial length and radial inclination were more in intra-articular subgroup than extra-articular subgroup in fixation with K-wire only group (p<0.05). No significant difference of reduction loss was noted between intra-articular and extra-articular subgroups in fixation with K-wire and external fixator group. CONCLUSION: More radiologic reduction loss can be expected in fixation with K-wire only group for intra-articular distal radius fracture compared with extra-articular distal radius fracture. Additional external fixation should be added in intra-articular distal radius fracture to reduce radiologic reduction loss.