Fixation of experimental osteotomies with absorbable polylactic acid screws.

Absorbable screws made of self-reinforced poly-L-lactic acid (SR-PLLA) and poly-DL/L-lactic acid (SR-PDLLA/PLLA) were used for fixation of cancellous bone osteotomies of the distal femur in rabbits. The initial molecular weight of PLLA was 260.000 and that of PDLLA 100.000. The follow-up times were from one week to 96 weeks. Seventy-two rabbits were operated on, 36 in the PLLA group and 36 in the PDLLA/PLLA group. After sacrifice, radiographic, micro-radiographic, histologic, histo-morphometric, and oxytetracycline-labelling studies were performed. In the PLLA group 34/36 (94%) osteotomies and in the PDLLA/PLLA group 31/36 (86%) osteotomies healed without delay or angular deformity. The present investigation shows that absorbable SR-polylactic acid screws are suitable for fixation of weight loading cancellous bone osteotomies in rabbits. Based on these promising results, a clinical study where cancellous bone fractures are fixed with SR-PLLA screws has been started.     

Biomechanical investigation of optimal fixation of isolated talonavicular joint fusion

Despite reports of high nonunion rates for isolated talonavicular fusion, this procedure may be indicated for some patients, including those for whom increased stability of the talonavicular joint in triple arthrodesis is needed. In the biomechanical cadaveric study reported here, we evaluated fixation methods used to provide optimal stability of talonavicular arthrodesis. A physiologic 3-point loading model was used to measure dorsal displacement of the navicular on the talus with 1 or 2 cannulated 4.5-mm screws across the talonavicular joint both with and without one 7.3-mm cannulated screw across the subtalar joint. Statistically significant differences in displacement under cyclic loading to one-half body weight were found. Use of 2 talonavicular screws and no subtalar screw or 1 talonavicular screw plus 1 subtalar screw decreased the motion, as compared with use of 1 talonavicular screw and no subtalar screw.     

Comparison of Initial Compression Force Across the Subtalar Joint by Two Different Screw Fixation Techniques

The purpose of this study was to compare the magnitude of compressive force across the posterior facet of the subtalar joint between 2 different screw orientations in a simulated subtalar fusion model fixated with cannulated 7.3-mm screws. Eight paired fresh, frozen cadaver feet were used. Before testing, the bone mineral density of the calcanei and tali was measured with dual energy x-ray absorptiometry to ensure comparable bone mineral density. The paired cadaver calcanei and tali were noted to have less than .05 g/cm(2) difference in bone mineral density. The paired specimens were each randomly assigned to 1 of 2 methods of fixation across the subtalar joint: a plantar approach, where the screw was oriented vertically from the plantar aspect of the calcaneus, distal to the tuberosity; and a posterior approach, where the screw was oriented obliquely from the posterior calcaneal tuberosity. A load-sensing washer was placed under the cancellous screw head before insertion of the screw to measure the magnitude of the compression force across the simulated fusion site. The mean compression force for the posterior-to-anterior approach was 581 N, with a standard deviation of 242 N. The mean force for the plantar-to-superior approach was 604 N, with a standard deviation of 276 N. The compression force obtained by the 2 approaches was not significantly different (P = .74). The plantar-to-superior fixation technique represents an alternative subtalar arthrodesis technique to the posterior-to-anterior approach, potentially allowing one to revise a previously failed arthrodesis when the standard fixation techniques cannot be applied.     

Biomechanical properties of bioabsorbable cannulated screws for surgical fixation of dislocated epiphysiolysis capitis femoris

Bioabsorbable materials are well suited for fixation of slipped capital femoral epiphysis (SCFE) as they are resorbable, compatible with magnetic resonance imaging, and well tolerated by the pediatric population. We compared cannulated 4.5-mm bioabsorbable screws made of self-reinforced polylevolactic acid (SR-PLLA) to cannulated 4.5-mm steel and titanium screws for their resistance to shear stress and ability to generate compression in a polyurethane foam model of SCFE fixation. The maximum shear stress resisted by the three screw types was similar (SR-PLLA 371 +/- 146, steel 442 +/- 43, titanium 470 +/- 91 MPa, NS). The maximum compression generated by both the SR-PLLA screw (68.5 +/- 3.3 N) and the steel screw (63.3 +/- 5.9 N) was greater than that for the titanium screw (3.0 +/- 1.4 N, p < 0.05). These data suggest that cannulated SR-PLLA screws have sufficient biomechanical strength to be used in the treatment of SCFE.     

Isolated subtalar arthrodesis

BACKGROUND: The purposes of this retrospective study were to review the results of isolated subtalar arthrodesis in adults and to identify factors influencing the union rate. The hypotheses were that (1) the overall outcome is acceptable but is not as favorable as previously reported, (2) complication rates, especially the nonunion rate, are higher than previously reported, and (3) factors contributing to a less favorable union rate can be identified. METHODS: Between January 1988 and July 1995, 184 consecutive isolated subtalar arthrodeses were performed in 174 adults (115 men and fifty-nine women) whose average age was forty-three years (range, eighteen to seventy-nine years). Eighty patients (46 percent) were smokers. The indications for the procedure included posttraumatic arthritis after a fracture of the calcaneus (109 feet), a fracture of the talus (thirteen feet), or a subtalar dislocation (thirteen feet); primary subtalar arthritis (thirteen feet); failure of a previous subtalar arthrodesis (twenty-eight feet); and residual congenital deformity (eight feet). Rigid internal fixation with one or two screws was used for all feet. Bone graft was used in 145 feet; the types of graft material included cancellous autograft (ninety-four feet), structural autograft (twenty-nine feet), cancellous allograft (seventeen feet), and structural allograft (five feet). Bone graft was not used in the remaining thirty-nine feet. RESULTS: Clinical and radiographic follow-up examinations were performed for 148 (80 percent) of the 184 feet at an average of fifty-one months (range, twenty-four to 130 months) postoperatively. The average ankle-hindfoot score according to the modified scale of the American Orthopaedic Foot and Ankle Society (maximum possible score, 94 points) improved from 24 points preoperatively to 70 points at follow-up. Thirty feet had clinical evidence of nonunion. The union rate was 84 percent (154 of 184) overall, 86 percent (134 of 156) after primary arthrodesis, and 71 percent (twenty of twenty-eight) after revision arthrodesis. The union rate was 92 percent (ninety-three of 101 feet) for nonsmokers and 73 percent (sixty-one of eighty-three feet) for smokers (p < 0.05). Intraoperative inspection revealed that 42 percent (seventy-eight) of the 184 feet had evidence of more than two millimeters of avascular bone at the subtalar joint; all thirty nonunions occurred in this group (p < 0.05). A nonunion occurred in three of the five feet that had been treated with structural allograft and in two of the six feet in which the subtalar arthrodesis had been performed adjacent to the site of a previous ankle arthrodesis. After elimination of the subgroups of feet in patients who smoked, those that had had a failure of a previous subtalar arthrodesis, those that had been treated with a structural graft, and those that had had the subtalar arthrodesis adjacent to the site of a previous ankle arthrodesis, the union rate improved to 96 percent (seventy-three of seventy-six). Complications other than nonunion included prominent hardware requiring screw removal (thirty-six of 184 feet; 20 percent), lateral impingement (fifteen of 148 feet; 10 percent), symptomatic valgus malalignment (five of 148 feet; 3 percent), symptomatic varus malalignment (four of 148 feet; 3 percent), and infection (five of 184 feet; 3 percent). CONCLUSIONS: To the best of our knowledge, the present study includes the largest reported series of isolated subtalar arthrodeses in adults. Our results suggest that the outcome following isolated subtalar arthrodesis is not as favorable as has been reported in previous studies. The rate of union was significantly diminished by smoking, the presence of more than two millimeters of avascular bone at the arthrodesis site, and the failure of a previous subtalar arthrodesis (p < 0.05 for all). Other factors that probably affect the union rate include the use of structural allograft and performance of the arthrodesis adjac     

小切口经皮空心螺钉内固定行距下关节融合术治疗距下关节炎

目的 探讨单纯小切口经皮空心螺钉内固定行距下关节融合术治疗距下关节炎的临床疗效.方法 2006年1月至2009年12月对26例(27足)保守治疗6个月以上无效的距下关节炎患者行距下关节融合治疗,男13例,女13例;平均年龄38.7岁(26～73岁);左侧11足,右侧16足.其中创伤性关节炎16例16足,类风湿关节炎6例7足,骨关节炎4例4足.术前平均病程8.3个月(6～25个月).手术采用外侧约4 cm切口,通过经皮穿针平行钻入2枚空心螺钉予以固定.术前和末次随访时采用视觉模拟法(VAS)疼痛评分和美国足踝外科协会(AOFAS)踝与后足评分分别对疼痛和功能进行评估.同时采用X线摄片和CT扫描进行影像学评估. 结果 26例患者术后获平均18 5个月(6～47个月)随访.术前与末次随访时VAS疼痛评分分别为(6.9±0.7)、(1.5±0.3)分,差异有统计学意义(t=17.000,P=0.000);AOFAS踝与后足评分分别为(54.3±12.1)、(82.6±11.3)分,差异有统计学意义(t=6.308,P=0.000).术后X线片或CT示26例患者全部获骨性融合,平均融合时间为10.8周(10～14周). 结论 小切口经皮穿针空心螺钉内固定行距下关节融合术治疗距下关节炎具有创伤小、恢复快、并发症少等优点,易于推广.     

Subtalar arthrodesis for late sequelae of calcaneal fractures: fusion in situ versus fusion with sliding corrective osteotomy

Primary subtalar arthritis is not common. In most cases, it is the late sequela of intra-articular calcaneal fracture. Subtalar arthrodesis is mostly used for the treatment of traumatic subtalar arthritis in our clinics. We have compared our early cases of in-situ subtalar fusion with our recent cases of fusion with sliding corrective osteotomy in this clinical report. From 1989 to 1992, 15 feet of 13 patients were treated with subtalar arthrodeses for subtalar arthritis caused by malunion of calcaneal fractures. Fusion in situ was done by Ollier's approach, and resection of bony protrusion was done if there was lateral entrapment syndrome. From 1992 to 1995, 13 feet of 12 patients also received subtalar arthrodeses to salvage their calcaneal fractures, but the subtalar fusion was done by wide lateral approach, calcaneal sliding corrective osteotomy, and sometimes (11 of 13 feet) with Achilles tendon lengthening to restore the calcaneal height and width. Patients of both groups experienced obvious clinical improvement in subtalar pain relief, but there was no difference with walking distance, running, or jumping. The group undergoing fusion with sliding corrective osteotomy was more satisfied with regard to cosmetic results and shoe wear. The overall satisfactory rate in the group who underwent fusion with sliding corrective osteotomy (92%) was superior to the group who underwent fusion in situ (77%). Though our method of sliding corrective osteotomy does not provide much improvement to the talus declination angle, it is suitable for those patients with a "banana"-shaped calcaneus malunion. If the patient has prominent anterior ankle pain caused by tibiotalar impingement, we believe that a distraction subtalar arthrodesis would be more appropriate.     

Foot and ankle fusions in Charcot-Marie-Tooth disease

Summary We reviewed 15 patients with Charcot-Marie-Tooth disease who were treated with foot or ankle fusions. Altogether, 26 feet were treated with fusions and the average follow-up time was 14 years. In half of the patients the principal symptom leading to fusion operation was instability of the ankle. In four patients, in two of them bilaterally, soft tissue corrections were performed before the fusion. In 21 cases, a subtalar triple arthrodesis was performed and each time correction to neutral position was the aim. In six feet, the triple arthrodesis was complemented by soft tissue plasties, e.g., plantar release, Achilles elongation, or transposition of tibial or peroneal tendons in order to achieve proper balance. Other primary fusions were a Grice-type fusion in one case, pantalar arthrodesis in one case, talocrural fusion in one case, and interphalangeal fusions in both feet in one patient with extreme claw foot. In four cases the triple arthrodesis failed to fuse (three nonunions and one delayed union), and new fusions were successful in three of them. The one pantalar fusion in the series was done for a 58-year-old man with late onset of the disease who had a very severe cavovarus deformity at the time of the operation, and this fusion failed to unite. In 17 of 26 feet, other operations than the primary fusion were performed, and five feet were operated on three or four times. In four feet the result was judged as excellent, in 15 good, in four fair, and in three poor. There were not more poor results in patients followed up for more than 15 years than in those whose follow-up was shorter. Evaluation of the surgical results in the present series suggests that triple arthrodesis can preserve acceptable function in the majority of patients with foot deformities and instabilities which are caused by Charcot-Marie-Tooth disease.     

Primary subtalar arthrodesis for the treatment of comminuted intra-articular calcaneal fractures

We report the short- and mid-term results in six patients (seven feet) affected by markedly comminuted intra-articular calcaneal fractures (Sanders type IV), treated by primary subtalar arthrodesis. The average age at surgery was 40 years. In all patients, arthrodesis of the subtalar joint was performed using a limited lateral approach to the calcaneus; it was stabilised with two or three cannulated screws. No patient had a preliminary reduction and internal fixation of the fracture. The time from injury to surgery averaged 20 days because all of the patients had associated visceral and/or other skeletal injuries. All of the patients were followed up clinically and radiographically 2 times, at an average of 12 months and 53 months after surgery. At the short-term follow-up, the mean AOFAS score was 70 points; the X-rays showed a complete fusion of the subtalar joint in all seven feet, without any sign of osteoarthritis of the calcaneo-cuboid and the talo-navicular joints. In all cases, an altered shape of the calcaneus was present. At the mid-term follow-up, the mean AOFAS score increased to 85 points; in one patient, radiographic signs of osteoarthritis of the calcaneo-cuboid and the talo-navicular joints were present and, in another patient, only talo-navicular joint was present, although both patients were free from pain. The difference between the two AOFAS scores was statistically significant. We believe that primary subtalar arthrodesis performed for markedly comminuted Sanders type IV calcaneal fractures yielded good mid-term results, and it is especially indicated when surgical treatment is delayed for whatever reason. A preliminary open reduction and internal fixation to restore the normal height of the calcaneus before performing the subtalar arthrodesis, as suggested by several authors, does not seem indispensable to obtain good clinical results.     

Primary stability of shoulder arthrodesis using cannulated cancellous screws

There are no biomechanical studies available concerned with the primary stability of shoulder arthrodesis. The aim of our biomechanical investigations was to ascertain a minimal material combination with high primary stability for shoulder arthrodesis. For that purpose, the primary stability of 6 different forms of screw arthrodesis was investigated under the stress of abduction, adduction, anteversion, and retroversion. The mean values of the screw arthrodeses were compared with those of a 16-hole plate arthrodesis. All tests were carried out on 24 human specimens without destruction by use of a materials testing machine. The most stable form of screw arthrodesis for the load directions of abduction, adduction, anteversion, and retroversion results from a specific configuration of screws comprising 3 horizontal humeroglenoid screws and 3 vertical acromiohumeral screws (318.5 +/- 99.0 N). For three forms of arthrodesis, each with 3 humerus-glenoid screws (299.9 +/- 95.4 N), no significant difference (P = .530) was found compared with a 16-hole plate arthrodesis (293.4 +/- 89.3 N). The plate arthrodeses only achieved higher power values on abduction and adduction stress in comparison with screw arthrodesis with 3 humerus-glenoid screws. The difference was insignificant. Because arthrodesis with 3 humerus-glenoid screws was significantly more stable on stress of anteversion and retroversion, this particular screw arthrodesis is considered superior to plate arthrodeses. The use of the most stable form of screw arthrodesis may reduce nonunion.     

Talocrural arthrodesis with absorbable screws, 12 cases followed for 1 year.

In 11 patients, 12 arthrodeses of the ankle joint were performed by using absorbable self-reinforced poly-l-lactide (SR-PLLA) or polyglycolide (SR-PGA) screws. 8 patients had posttraumatic arthrosis, 3 rheumatoid arthritis, and 1 rigid flexion contracture of the ankle due to neuropathy. The average follow-up time was 14 (7-22) months. Solid fusion was achieved in 11 of 12 cases in 9(6-16) weeks.     

Posterior Arthroscopic Subtalar Arthrodesis: Clinical and Radiologic Review of 19 Cases

Arthroscopic subtalar arthrodesis has recently gained popularity in the treatment of primary subtalar or post-traumatic arthritis, coalition, or inflammatory diseases with subtalar arthritis. The present study reports the clinical and radiologic results of 19 patients (19 feet) who underwent posterior arthroscopic subtalar arthrodesis using 2 posterior portals. A total of 19 posterior arthroscopic subtalar arthrodeses (minimum follow-up of 24 months) performed without a bone graft and with 2 parallel screws were prospectively evaluated. The fusion rate was 94% (mean time to fusion 9.8 weeks). Modified American Orthopaedic Foot and Ankle Society ankle-hindfoot scale score (maximum 94 points) improved significantly from 43 to 80 points and the visual analog scale for pain score improved from 7.6 to 1.2. The 12-item short-form physical and mental scores at the last follow-up point were 52.5 and 56.4, respectively. One (5.3%) patient underwent open repeat fusion for nonunion, 2 (10.5%) patients required a second procedure for implant removal, and 1 (5.3%) experienced reversible neuropraxia. In conclusion, posterior arthroscopic subtalar arthrodesis is a safe technique with a good union rate and a small number of complications in patients with no or very little hindfoot deformity.     

Biomechanical Evaluation of Subtalar Fusion: The Influence of Screw Configuration and Placement

Common surgical procedures for subtalar fusion include joint resection, autologous bone grafting, and osteosynthesis with screws in a parallel screw configuration. Although fusion is a routine procedure, the reported rates of nonunion have been high. The present study assessed different screw configurations in terms of their rotational and bending stability in an artificial bone model and cadaver bone. Arthrodesis was always performed with 2 screws. Three different screw configurations were tested: parallel, counter-parallel, and a delta configuration. Two different screw designs were used: a cannulated, partially threaded screw (6.5-mm and 8.0-mm diameter) and a solid screw with a different thread design. Eight experimental groups were investigated as pilot studies in artificial bones and then 3 groups in cadaver bones. The parameters were the primary stiffness and deflection of the construct for loads simulating the internal–external rotation and supination–pronation. Delta positioning of the screws resulted in the greatest biomechanical stiffness and the lowest degrees of deflection of the arthrodesis in the artificial bones and cadaver bones. Increasing the screw diameter from 6.5 to 8.0 mm resulted in no additional stability of the arthrodesis in the artificial bones. The results of the present study have indicated that the delta configuration for arthrodesis results in the greatest construct stiffness and lower relative deflection between the talus and calcaneus in the positions tested.     

下颈椎经关节螺钉联合侧块或椎弓根螺钉固定的效果

目的 探讨在下颈椎经颈后正中入路应用经关节螺钉联合侧块螺钉或椎弓根螺钉行内固定治疗的固定效果.方法 2003年2月至2007年10月,对22例患者通过后路应用经关节螺钉联合侧块螺钉或椎弓根螺钉行内固定治疗,男14例,女8例;年龄24～73岁,平均43岁.其中下颈椎创伤性骨折脱位13例,颈椎后纵韧带骨化症4例,颈椎管狭窄伴Ⅱ型齿突骨折1例,颈椎间盘突出伴椎管狭窄4例.结果 共置入经关节螺钉45枚,其中C4,5 2枚,C5,639枚,C6,74枚;共置入侧块螺钉12枚,C3、C4各6枚;共置入椎弓根螺钉41枚,其中C24枚,C32枚,C46枚,C721枚,T18枚.术中所有螺钉均成功置入,未出现椎动脉、神经根和脊髓损伤等置钉相关并发症.22例患者均获随访,随访时间10个月～3年8个月,平均17个月.植骨融合时间3～5个月,平均3.5个月.术后发现1例患者的2枚经关节螺钉松动,部分脱出.经加强颈托制动,术后4个月获得融合.结论 通过后路固定下颈椎时,采用经关节螺钉联合侧块螺钉或椎弓根螺钉固定,均可取得较好的固定效果.     

Ankle arthrodesis for failed total ankle replacement

Between 1999 and 2005, 23 failed total ankle replacements were converted to arthrodeses. Three surgical techniques were used: tibiotalar arthrodesis with screw fixation, tibiotalocalcaneal arthrodesis with screw fixation, and tibiotalocalcaneal arthrodesis with an intramedullary nail. As experience was gained, the benefits and problems became apparent. Successful bony union was seen in 17 of the 23 ankles. The complication rate was higher in ankles where the loosening had caused extensive destruction of the body of the talus, usually in rheumatoid arthritis. In this situation we recommend tibiotalocalcaneal arthrodesis with an intramedullary nail. This technique can also be used when there is severe arthritic change in the subtalar joint. Arthrodesis of the tibiotalar joint alone using compression screws was generally possible in osteoarthritis because the destruction of the body of the talus was less extensive. Tibiotalocalcaneal arthrodesis fusion with compression screws has not been successful in our experience.     

Technique and early experience with posterior arthroscopic subtalar arthrodesis

BACKGROUND: Subtalar arthrodesis is a reliable procedure for pain relief and improved function in patients with isolated subtalar arthritis. Arthroscopic subtalar arthrodesis (ASTA) was designed to improve upon traditional methods by using a minimally invasive technique. However, posterior arthroscopic subtalar arthrodesis (PASTA) has not been described. The purpose of the present study was to investigate the early results of PASTA. METHODS: A retrospective review of 11 feet in 10 patients (one bilateral) that had PASTA was conducted. Inclusion criteria were isolated subtalar arthritis with no or minimal deformity and no significant bone loss. Exclusion criteria included patients requiring adjunctive open procedures or who had significant deformity. The technique involved prone positioning, two posterolateral portals and one posteromedial portal, posterior talocalcaneal facet debridement, percutaneous cancellous allografting and internal screw fixation. Outcome measures included patient satisfaction, the modified American Orthopaedic Foot and Ankle Society (AOFAS) score, union rate, time to union, and postoperative complications. RESULTS: All patients were discharged the day of surgery or stayed one night in the hospital. Eight patients were very satisfied, one satisfied, and one patient not satisfied with the results of their surgery. The average modified AOFAS score (maximum 94 points) improved from 36 points preoperatively to 86 points postoperatively. Ten joints fused by 10 weeks postoperatively, and one patient developed a nonunion. No other postoperative complications occurred. CONCLUSIONS: For surgeons familiar with posterior ankle or subtalar arthroscopy, PASTA offers superior exposure of the posterior talocalcaneal facet, high patient satisfaction, an excellent fusion rate, and less postoperative morbidity for patients with subtalar arthritis.     

The results of a primary and staged pantalar arthrodesis and tibiotalocalcaneal arthrodesis in adult patients

Twenty-three patients (twenty-seven feet) with either a primary or staged pantalar arthrodesis or a tibiotalocalcaneal arthrodesis were evaluated to determine their clinical status. The main indication for the operation was the presence of severe pain unresponsive to non-operative treatment. Fourteen feet (twelve patients) had a pantalar arthrodesis; a fusion of the ankle, subtalar, talonavicular and calcaneocuboid joints. Half the feet in this group had either a triple arthrodesis or an ankle fusion performed at an earlier time. The remaining seven feet had all joints fused during the same operation. Thirteen feet (eleven patients) had a tibiotalocalcaneal arthrodesis. Two of these feet had an ankle arthrodesis performed four and six years previously. The other eleven had the ankle and subtalar joints fused during the same operation. All patients were followed for a mean of fifty-five months (14 to 159 months) from the time of their final arthrodesis procedure. Overall, twenty-three of the twenty-seven feet achieved a solid arthrodesis of all joints operated upon. Four feet had a failure of fusion of only a single joint and all were in the pantalar group. The mean time to radiographic fusion was twenty-three weeks and resulted in a plantigrade foot with an average tibia-floor angle of 87 degrees. Complications occurred in ten feet (37%); of which there were three deep infections; two ankles and one subtalar joint. These arthrodeses procedures resulted in marked relief of the patients' preoperative pain, the main indication for performing the surgery. Postoperatively there was no pain in eleven feet, mild occasional pain in thirteen feet, and moderate pain in only three feet. However, when all parameters of our clinical rating scale were evaluated, only five patients had an excellent clinical result, nine were rated good, three were rated fair and six patients had a poor result. These operations must be considered to be salvage procedures. They are technically difficult to perform and major complications may occur. Pain relief appears to be the main indication for performing these operations, and may account for whatever improvement occurs in the patient's function.     

微创距下关节融合术治疗距下关节创伤性关节炎的实验研究

目的 探讨应用阶梯钻微创距下关节融合治疗距下关节创伤性关节炎的可行性,以及不同阶梯钻角度获得的距下关节融合面积及所占后关节面百分比对疗效的影响.方法 选取成人足标本22具,随机分为A、B两组(每组11具).C型臂X线机透视下向距下关节方向打入1枚导针,A组用空心钻沿导针向距下关节钻取隧道,再以动力髋螺钉阶梯钻扩大隧道;B组在A组基础上将阶梯钻于内、外侧各倾斜20°～25°钻入,以增加融合面积.取髂骨松质骨并剪成碎骨块向隧道内打压植骨,空心螺钉固定距下关节.比较两组中距骨、跟骨相对关节面的轴向融合面积及其占后关节面面积的百分比.结果 距下关节融合隧道内关节软骨完全清除,未伤及内外侧关节囊韧带等软组织.植骨块充分填充于融合隧道,未遗留空腔.A组距骨侧轴向融合面积为(293±34)mm2,跟骨侧轴向融合面积为(321±56)mm2,占后关节面面积的百分比分别为43.3%和47.4%,B组中距骨侧轴向融合面积为(433±19)mm2,跟骨侧轴向融合面积为(515±37)mm2,占后关节面面积的比例分别为64.3%和76.1%.两组距骨、跟骨轴向融合面积差异均有统计学意义(P＜0.05).结论 阶梯钻微创距下关节融合术操作安全、方便,对周围软组织影响小,适当调整阶梯钻角度后再次钻入可获得满意的距下关节融合面积,从而提高融合率.

Abstract：

Objective To evaluate feasibility of the minimally invasive subtalar arthrodesis for subtalar traumatic arthritis with a subland drill for dynamic hip screw (DHS),and effects of different fusion areas and their proportions to the posterior articular facet on the treatment. Methods Twenty-two frozen cadaveric specimens of adult feet were randomly assigned into 2 equal groups.In group A,after a guide pin was inserted into the subtalar joint,atunnel was made with a hollow drill along the guide pin.Next the tunnel was expanded with a DHS subland drill.In group B,the tunnel was enlarged to increase the fusion area by driving the DHS subland drill medially and laterally about 20° to 25° respectively,in addition to all the steps of group A.In both groups,morselized spongy bone of ilium was impacted into the tunnel before the subtalar joint was fixed with a hollow screw at last.The axial fusion areas of the talus and calcaneus and their proportions to the posterior articular facet were calculated respectively for both groups and compared. Results The articular cartilage in the tunnel was removed completely and the surrounding soft tissue was not disturbed.The grafted bone was impacted in the tunnel fully and no vacant space left.In group A,the axial talar and calcaneal fusion areas were 293 ± 34 mm2 and 321 ± 56 mm2,which accounted for 43.3％ and 47.4％ of the posterior articular facet respectively.In group B,the axial talar and calcaneal fusion areas were 433 ± 19 mm2 and 515 ±37 mm2,which accounted for 64.3％ and 76.1％ of the posterior articular facet respectively.The differences in the fusion areas were significant between the 2 groups ( P ＜ 0.05 ). Conclusions The procedure of minimally invasive subtalar arthrodesis with a DHS subland drill is safe because the damage to the surrounding soft tissue is minimal.Furthermore,this simple method has a benefit of achieving a broader fusion area,which can facilitate subtalar fusing and reduce complications theatrically.     

Fixation of osteotomies of the distal femur with absorbable, self-reinforced, poly-L-lactide plates

Osteotomies of the distal femur were fixed with two self-reinforced poly-L-lactic acid (SR-PLLA) plates and metallic screws placed through the plates on each side of the femur in 23 adult rabbits. They were followed-up after 3, 6, 12 and 24 weeks. After killing, radiological, histological, microradiographic and oxytetracycline fluorescence studies were performed. Except for one histologically confirmed fibrotic non-union at 24 weeks, the osteotomies healed, including one involving a rabbit which had suffered an ipsilateral femoral shaft fracture of unknown cause. No malformations were observed, and the macroscopically detected swelling was a normal postoperative reaction. This study showed that SR-PLLA plates implanted on both sides on the bone are suitable for the fixation of weight-bearing cancellous bone osteotomies in rabbits.     

Bioabsorbable interference screws for graft fixation in anterior cruciate ligament reconstruction.

The central one third of the patellar tendon autograft is popular because the bone-tendon-bone (BTB) construct provides several graft fixation options, robust graft incorporation, and a mechanically sufficient substitute. Interference screw fixation is one method used to secure the graft. Bioabsorbable interference screws may offer advantages over metal interference screws. Bioabsorbable screws are made from poly L-lactic acid (PLLA) and are absorbed by the body. This prospective, randomized study compared the safety and efficacy of the PLLA screw with that of the metal cannulated interference screw for anterior cruciate ligament reconstruction. There were 204 patients randomly assigned to the Bioscrew (Linvatec, Largo, FL) (n = 103) or the metal interference screw (n = 101) groups at four sites. The mean age was 30 years. There were 66 women and 138 men. Mean follow-up was 30 months for Bioscrews and 28 months for metal screws; the average follow-up interval was 2.4 years. The Lysholm mean scores at 4 years for the 32 patients seen at this interval were 95.0 and 97.2 for the Bioscrew and metal screw group, respectively. Ligament laxity comparisons made with an instrumented arthrometer at manual maximum force resulted in side-to-side mean score differences of B = 1.8mm and M = 1.6mm. The Tegner activity level score means were B = 6.1 and M = 5.8. Other variables examined included pain, thigh size, meniscal tests, Lachman's test, range of motion, anterior drawer, pivot shift, patellofemoral crepitus and tenderness, and joint effusion. None of these variables showed a statistically significant difference between groups. No radiographic evidence of osteolytic change or bone resorption around the Bioscrews was observed. There were no complications related to loss of fixation, toxicity, allergenicity, or other evidence of osteolytic or inflammatory reaction. In every assessment between groups there was no difference found. There were 12 PLLA screws that broke during insertion without any adverse effects. The PLLA headless cannulated interference fit screws produce equal results to similarly designed metal screws.