Assessment of the Initial Result of Screw Fixation for Proximal Crescentic Metatarsal Osteotomy with Distal Soft Tissue Reconstruction in Severe Hallux Valgus Treatment.

INTRODUCTION: Proximal crescentic metatarsal osteotomy and distal soft tissue reconstruction have been introduced to correct severe HV. The intrinsically unstable proximal first crescentic osteotomy depends on enough force fixation for stability. It is necessary to judge the number of fixation screws for osteotomy. METHOD: Fifty-two feet of 50 adult patients with severe HV were included in this study. The treatment was proximal crescentic metatarsal osteotomy with a single screw and distal soft tissue reconstruction in Group 1 and the fixation with two screws with distal soft tissue reconstruction in Group 2. Clinical and radiological follow-ups were assessed after 4 and 12 months of operation. In Group 1, HVA decreased from 46.4 ±3.28 to 19.9 ±4.70 after 12 months of operation and from 45.1 ±3.45 to 19.1 ±4.70 in Group 2. Regarding the intermetatarsal angle (IMA) in Group 1, it was changed from 18.5 ±1.98 to 9.25 ±1.11 after 12 months of operation. For group 2, it decreased from 18.3 ±1.81 to 9.53 ±1.70. Meanwhile, the AOFAS score improved from 63.1 to 83.9 after 12 months of operation in Group 1 and improved from 64.3 to 82.8 in Group 2. RESULTS: Furthermore, the VAS score reduced from 4.5±1.01 to 1.7± 0.43 in Group 1 and from 4.7±0.92 to 1.7±0.55 in Group 2 after 12 months of operation. There were no significant differences identified between Group 1 and Group 2 in terms of VAS and AOFAS scores and HVA and IMA measurements. CONCLUSION: There is less complication in two-screw fixation for crescentic osteotomy compared to a single-screw fixation.

Comparison of a minimally invasive osteosynthesis technique with conventional open surgery for transverse patellar fractures.

PURPOSE: The study aims to compare the efficacy and safety of a new minimally invasive osteosynthesis technique with those of conventional open surgery for transverse patellar fractures. METHODS: It was a retrospective study. Adult patients with closed transverse patellar fracture were included, and with open comminuted patellar fracture were excluded. These patients were divided into minimally invasive osteosynthesis technique (MIOT) group and open reduction and internal fixation (ORIF) group. Surgical time, frequency of intraoperative fluoroscopy, visual analogue scale score, flexion, extension, Lysholm knee score, infection, malreduction, implant migration and implant irritation in two groups were recorded and compared. Statistical analysis was performed by the SPSS software package (version 19). A p < 0.05 indicated statistical significance. RESULTS: A total of 55 patients with transverse patellar fractures enrolled in this study, the minimally invasive technique was performed in 27 cases, and open reduction was performed in 28 cases. The surgical time in the ORIF group was shorter than that in the MIOT group (p = 0.033). The visual analogue scale scores in the MIOT group were significantly lower than those in the ORIF group only in the first month after surgery (p = 0.015). Flexion was restored faster in the MIOT group than that in the ORIF group at one month (p = 0.001) and three months (p = 0.015). Extension was recovered faster in the MIOT group than that in the ORIF group at one month (p = 0.031) and three months (p = 0.023). The recorded Lysholm knee scores in the MIOT group were always greater than those in the ORIF group. Complications, such as infection, malreduction, implant migration, and implant irritation, occurred more frequently in the ORIF group. CONCLUSION: Compared with the ORIF group, the MIOT group reduced postoperative pain and had less complications and better exercise rehabilitation. Although it requires a long operation time, MIOT may be a wise choice for transverse patellar fractures.

Per- and polyfluoroalkyl substances exposure and bone mineral density in the U.S. population from NHANES 2005-2014.

BACKGROUND: Environmental exposures such as perfluoroalkyl substances (PFASs) were considered potential risks for bone mineral density (BMD). OBJECTIVE: To examine the associations between PFASs and BMD among the U.S. population. METHODS: This study included a total of 6416 participants from the National Health and Nutrition Examination Survey (NHANES 2005-2014). Multiple linear regression models were used to analyze the associations between serum PFASs and BMD and the coefficient ß with 95% confidence intervals (95% CI) was calculated as the effect estimate. Covariates such as age, race, BMI, smoking, alcohol intake, milk intake, and physical activity were adjusted in these models. Additionally, gender and menopausal period were considered in further subgroup analyses. RESULTS: Based on the combined data of NHANES 2005-2014, the effects from exposure to PFASs on BMD were found with gender and menopausal status differences. Positive associations were found in PFOA (ß = 0.010; 95% CI: 0.003, 0.016), PFHxS (ß = 0.007; 95% CI: 0.003, 0.012), and PFNA (ß = 0.001; 95% CI: 0.001, 0.017) in total population. Negative associations for PFOA (ß = -0.020; 95% CI: -0.029, -0.012), PFOS (ß = -0.011; 95% CI: -0.028, -0.011), PFHxS (ß = -0.019; 95% CI: -0.025, -0.013), PFDE (ß = -0.010; 95% CI: -0.016, -0.005), and PFNA (ß = -0.011; 95% CI: -0.021, -0.002) were found in women, while no significant association was found in men. In further subgroup analyses, women in pre-menopause status showed consistent negative associations. SIGNIFICANCE: PFASs exposure may be associated with BMD and gender and menopausal status confound the associations.

Ultrasound-guided interscalene block versus intravenous analgesia and sedation for reduction of first anterior shoulder dislocation.

PURPOSE: This study aims to compare the efficacy of ultrasound-guided interscalene block (US-ISB) with that of intravenous analgesia and sedation (IVAS) in reducing first shoulder dislocation. MATERIAL AND METHODS: A prospective study was performed in 66 patients with first anterior shoulder dislocation in emergency department. The patients were divided into a US-ISB (n = 32) group and an IVAS (IVAS n = 34) group. The procedure time (anesthesia, reduction, and hospital times), pain score (before, during, and after reduction), reduction attempts, complications, and patient satisfaction were recorded and compared between the two groups. RESULTS: The anesthesia time (P < 0.01) and reduction time (P < 0.01) were shorter and the hospital time (P < 0.01) was longer in the IVAS group than in the US-ISB group. No significant differences in preoperative (P = 0.18) and postoperative (P = 0.27) pain scores were found between the two groups, but the intraoperative score of the US-ISB group was significantly higher than that of the IVAS group. More reduction attempts (P < 0.01) were recorded in the US-ISB group than that in the IVAS group. Complications (P < 0.01) such as nausea, vomiting, headache, and hypoxia occurred more frequently in the IVAS group than in the US-ISB group. No significant difference in patient satisfaction was observed between two groups (P = 0.96). CONCLUSION: Compared with IVAS group, US-ISB group reduces the time to discharge and achieves lesser complication. The pain score and reduction attempt are lower in the IVAS group than in the US-ISB group.

[Minimally-invasive internal fixation for mid-lateral 1/3 clavicle fracture with distal clavicular anatomic locking plate].

OBJECTIVE: To investigate clinical effects of minimally-invasive internal fixation for mid-lateral 1/3 clavicle fracture with distal clavicular anatomic locking plate. METHODS: From February 2016 to March 2017, 32 patients with mid-lateral 1/3 clavicle fractures treated by minimally-invasive internal fixation with distal clavicular anatomic locking plate, including 24 males and 8 females with an average of (42.3±12.7) years old (ranged from 22 to 68 years old). According to Robinson classification, 6 patients were type 2A2, 18 patients were type 2B1 and 8 patients were type 2B2. No vessel and nerve injury occurred before operation. The time from injury to operation ranged from 0 to 6 days with an average of (3.1±1.4) days. Length of bilateral clavicule were compared before and after operation to evaluate fracture reduction. Constant score at 6 months after operation was applied to assess recovery of shoulder function. RESULTS: Thirty patients were followed up from 11 to 18 months with an average of (13.3±2.2 ) months. No vessel and nerve injury, implant failure, nonunion or delayed union occurred after operation, and facture wound healed at stage I, the time ranged from 8 to 12 weeks with an average of(10.2±1.1) weeks. Shortened length of clavicle decreased from(11.2±3.6) % before operation to (0.4±0.3)% after operation at 2 days. Ten patients removed internal fixation at 8 months after operation without re-fracture occurred after remove plate. Constant score increased from 23.53±5.21 before operation to 94.30±5.60 after operation at 6 months, and 26 patients got excellent results, and 4 good. Patients were satisfied aesthetic degree of scar and shoulder joint function. CONCLUSIONS: Minimally-invasive internal fixation for mid-lateral 1/3 clavicle fracture with distal clavicular anatomic locking plate, which has advantages of less trauma, rapid recover, less scar, could receive good clinical effects and not effect beauty.

[Descending branch of anterior lateral malleolar artery based anterograde island flaps for reconstruction of foot and ankle defects].

OBJECTIVE: To explore surgical method and clinical effects of descending branch of the anterior lateral malleolar artery based anterograde island flap for repairing foot and ankle wounds. METHODS: Nine patients with skin defects of foot and ankle repaired by descending branch of the anterior lateral malleolar artery based anterograde island flap were studied from June 2015 to January 2017, including 6 males and 3 females aged from 32 to 63 years old. The wound were located on foot and ankle and associated with exposure of bone, tendon, blood vessels or nerves. The surface of wound located on foot in 6 patients, and 3 patients in ankle joint. The area of defect ranged from 1.5 cm×2.0 cm to 6.0 cm×13.0 cm, and the area of flap ranged from 2.0 cm×3.0 cm to 7.0 cm×15.0 cm. The donor site was skin grafted with split-thickness skin from abdomen. Appearance, texture, condition of donor site of island flaps after operation were observed, satisfied degree of clinical effects were evaluated by ZHANG Hao's evaluation, and AOFAS score were used to evaluate function. RESULTS: Circulations of flaps in 9 cases were stable without blockage, and healed well at 2 weeks after operation. All patients were followed up from 2 to 18 months with an average of(8.0±2.3) months. All flap were survived at stage I, pedicles looked smooth and tidy, no cat-ear formed, the texture of flap was soft with satisfied appearance, the color was near to surrounding skin. The surface of wound were tidy after skin graft of donor sites without scar hypertrophy. Nine patients got satisfied results according to ZHANG Hao's evaluation, and AOFAS score was excellent. CONCLUSIONS: Descending branch of the anterior lateral malleolar artery based anterograde island flap for repairing foot and ankle wounds, which has advantages of protect main vessel, thin flap, is a simple and effective method.

Anatomical feasibility study of flexor hallucis longus transfer in treatment of Achilles tendon and posteromedial portal of ankle arthroscopy.

PURPOSE: The aim of this study was to evaluate the occurrence of anatomical variations of the musculotendinous junction of the flexor hallucis longus (FHL) muscle, the relationship between FHL tendon or muscle and the tibial neurovascular bundle at the level of the posterior ankle joint in human cadavers. METHODS: Seventy embalmed feet from 20 male and 15 female cadavers, the cadavers' mean age was 65.4 (range from 14 to 82) years, were dissected and anatomically classified to observe FHL muscle morphology define the relationship between FHL tendon or muscle and the tibial neurovascular bundle. The distance between the musculotendinous junction and the relationship between FHL tendon or muscle and the tibial neurovascular bundle was determined. RESULTS: Three morphology types of FHL muscle were identified: a long lateral and shorter medial muscle belly, which was observed in 63 specimens (90%); equal length medial and lateral muscle bellies, this variant was only observed in five specimens (7.1%); one lateral and no medial muscle belly, which was observed in two specimens (2.9%). No statistically significant difference was observed according to gender or side (p > 0.05). Two patterns were identified and described between FHL tendon or muscle and the tibial neurovascular bundle. Pattern 1, the distance between the neurovascular bundle and FHL tendon was 3.46 mm (range 2.34-8.84, SD = 2.12) which was observed in 66 specimens (94.3%); Pattern 2, there was no distance which was observed in four specimens (5.7%). CONCLUSION: Knowing FHL muscle morphology, variations provide new important insights into secure planning and execution of a FHL transfer for Achilles tendon defect as well as for the interpretation of ultrasound and magnetic resonance images. With posterior arthroscopic for the treatment of various ankle pathologies, posteromedial portal may be introduced into the posterior aspect of the ankle without gross injury to the tibial neurovascular structures because of the gap between the neurovascular bundle and FHL tendon.

Anatomical Study of the Neurovascular in Flexor Hallucis Longus Tendon Transfers.

The transfer of the flexor hallucis longus tendon or flexor digitorum longus tendon is frequently used for the treatment of posterior tibial tendon insufficiency or chronic Achilles tendinopathy. According to several anatomical studies, harvesting the flexor hallucis longus (FHL) tendon may cause nerve injury. Sixty-eight embalmed feet were dissected and anatomically classified to define the relationship between Henry's knot and the plantar nerves. Two different configurations were identified. In Pattern 1, which was observed in 64 specimens (94.1%), the distance between the medial plantar nerve and Henry's knot was 5.96 mm (range, 3.34 to 7.84, SD = 1.12). In Pattern 2, which was observed in 4 specimens (5.9%), there was no distance between the medial plantar nerve (MPN) and Henry's knot. No statistically significant difference was observed according to gender or side (p > 0.05). A retraction was performed to harvest the FHL through the posteromedial hindfoot incision using a single minimally invasive technique, and the medial and lateral plantar nerve lesions were scrupulously assessed. In conclusion, medial and lateral plantar nerve injuries did not occur more frequently, even after performing a single minimally invasive incision to harvest the FHL tendon, due to the large distance between the FHL tendon and the medial and lateral plantar nerves.

Efficacy and safety of bisphosphonates in management of low bone density in inflammatory bowel disease: A meta-analysis.

This study aims to determine whether bisphosphonates are safe, as well as effective against bone mineral loss in inflammatory bowel disease (IBD). A computerized search of electronic databases from 1966 to 2016 was performed. Randomized controlled trials (RCTs) were included in this review to evaluate the role of bisphosphonates in the management of osteoporosis in IBD patients. A revised 7-point Jadad scale was used to evaluate the quality of each study. Overall, 13 RCTs and 923 patients met the inclusion criteria of this meta-analysis. The result showed that bisphosphonates decreased bone mass density (BMD) loss at the lumbar spine (P = 0.0002), reduced the risk of new fractures (P = 0.01), and retained the similar adverse events (P = 0.86). Bisphosphonates may provide protection and safety against bone mineral loss in IBD patients.

Identification of CHD1L as an Important Regulator for Spermatogonial Stem Cell Survival and Self-Renewal.

Chromodomain helicase/ATPase DNA binding protein 1-like gene (Chd1l) participates in chromatin-dependent processes, including transcriptional activation and DNA repair. In this study, we have found for the first time that Chd1l is mainly expressed in the testicular tissues of prepubertal and adult mice and colocalized with PLZF, OCT4, and GFRα1 in the neonatal mouse testis and THY1+ undifferentiated spermatogonia or spermatogonial stem cells (SSCs). Knockdown of endogenous Chd1l in cultured mouse undifferentiated SSCs inhibited the expression levels of Oct4, Plzf, Gfrα1, and Pcna genes, suppressed SSC colony formation, and reduced BrdU incorporation, while increasing SSC apoptosis. Moreover, the Chd1l gene expression is activated by GDNF in the cultured mouse SSCs, and the GDNF signaling pathway was modulated by endogenous levels of Chd1l; as demonstrated by the gene expression levels of GDNF, inducible transcripts Etv5, Bcl6b, Pou3f, and Lhx1, but not that of GDNF-independent gene, Taf4b, were significantly downregulated by Chd1l knockdown in mouse SSCs. Taken together, this study provides the first evidence to support the notion that Chd1l is an intrinsic and novel regulator for SSC survival and self-renewal, and it exerts such regulation at least partially through a GDNF signaling pathway.

Indirect reduction technique using a distraction support in minimally invasive percutaneous plate osteosynthesis of tibial shaft fractures.

PURPOSE: To describe an indirect reduction technique during minimally invasive percutaneous plate osteosynthesis (MIPPO) of tibial shaft fractures with the use of a distraction support. METHODS: Between March 2011 and October 2014, 52 patients with a mean age of 48 years (16-72 years) sustaining tibial shaft fractures were included. All the patients underwent MIPPO for the fractures using a distraction support prior to insertion of the plate. Fracture angular deformity was assessed by goni- ometer measurement on preoperative and postoperative images. RESULTS: Preoperative radiographs revealed a mean of 7.6°(1.2°-28°) angulation in coronal plane and a mean of 6.8°(0.5°-19°) angulation in sagittal plane. Postoperative anteroposterior and lateral radio- graphs showed a mean of 0.8°(0°-4.0°) and 0.6°(0°-3.6°) of varus/valgus and apex anterior/posterior angulation, respectively. No intraoperative or postoperative complications were noted. CONCLUSIONS: This study suggests that the distraction support during MIPPO of tibial shaft fractures is an effective and safe method with no associated complications.

[Treatment of complete acromioclavicular joint dislocation with transfer of the medial half of the coracoacromial ligament to reconstruct the coracoclavicular ligament].

OBJECTIVE: To explore the operation methods and clinical effects of transfer of the medial half of the coracoacromial ligament to reconstruct the coracoclavicular ligament in treating complete acromioclavicular joint dislocation. METHODS: From January 2006 to June 2012,26 patients with acute complete acromioclavicular joint dislocation underwent surgery. Transfer of the medial half of the coracoacromial ligament to reconstruct the coracoclavicular ligament, additional clavical hoot plate and Kirschner wires fixation, were performed in all the patients. Among the patients, 18 patients were male and 8 patients were female, with an average age of 36.7 years old (ranged from 25 to 51 years). The duration from injury to operation was from 3 to 12 days with an average of 5 days. According to the Rockwood classification, 4 cases were grade III and 22 cases were grade V . Clinical manifestation included local swelling, tenderness with snapping, limitation of shoulder joint motion. In preoperative bilateral shoulder joint X-rays, the injured coracoclavicular distance was (16.2 ± 5.0) mm which was significantly wider than that of uninjured sides (7.6 ± 1.0) mm. Clinical results were evaluated according to X-rays and Constant-Murley score. RESULTS: All incisions obtained primary healing after operation without complication of infection, internal fixation breakage, redislocation. All the patients were followed up from 12 to 30 months with an average of 18 months. Kirschner wires and internal fixation plate were removed at 1 month and 8-10 months after operation, respectively. At final follow-up, the motion of shoulder joint recovered to normal and a no pain joint was obtained. According to Constant-Murley score, 24 cases got excellent results and 2 cases good. There was no significant difference after operation between the injured coracoclavicular distance and the uninjured contralateral side [(7.7 ± 1.2) mm vs (7.6 ± 1.0) mm), P > 0.05]. CONCLUSION: Transfer of the medial half of the coracoacromial ligament to reconstruct the coracoclavicular ligament, additional fixation using hook plate and Kirschner wires is the effective surgical method in treating complete acute acromioclavicular joint dislocation.

[The proximal crescentic osteotomy of the first metatarsal bone combined distal soft tissue reconstruction to treat severe hallux valgus].

OBJECTIVE: To explore the method of the treatment for hallux valgus with the proximal crescentic osteotomy of the first metatarsal bone, combining with distal lateral soft tissue release. METHODS: From January 2008 to December 2012, 21 cases 21 hallux valgus feet were treated by operative procedure, included 1 male (1 foot) and 20 females (20 feet), with the mean age of 52 years (range, 36-68 years). Among all patients were followed up for 12 to 26 months, with the mean 16 months. The preoperative, post-operative and final follow-up X-ray films of all patients were collected. The hallux valgus angle, intermetatarsal angle and distal metatarsal articular angle were measured and analyzed. The surgical outcome was evaluated combined with the AOFAS score. RESULTS: The average hallux valgus angle decreased from 42.3° ± 1.8° preoperatively to 14.5° ± 1.8 postoperatively, the average intermetatarsal angle did from 21.9° ± 1.7 to 9.1° ± 1.8°, and the average distal metatarsal articular angle did from 14.9° ± 1.8 to 7.2° ± 1.5, respectively. There were significant differences between the preoperative and postoperative roentgenographic index. AOFAS score was improved from 44.0 ± 1.8 preoperatively to 83.9 ± 2.2 at the final follow-up. CONCLUSIONS: The proximal crescentic osteotomy of the first metatarsal bone combined distal soft tissue reconstruction obtained satisfactory results in severe hallux valgus patients with big intermetatarsal angle.

Anatomical study for flexor hallucis longus tendon transfer in treatment of Achilles tendinopathy.

PURPOSE: The purpose of the study was to describe the anatomical variations of the connection between the flexor hallucis longus (FHL) and flexor digitorum longus (FDL) tendons in the knot of Henry in Asians, and quantify the length of FHL tendon graft with different incisions. METHODS: Sixty-four embalmed feet of 32 cadavers were analyzed anatomically with respect to the individual cross-links in the planta pedis. Single incision technique graft length was measured from the musculotendinous junction of FHL and the point at sustentaculum tali. Double incision technique was measured from musculotendinous junction of FHL and the level of the master knot of Henry. Additionally, minimally invasive incision technique was measured from musculotendinous junction of FHL to the first interphalangeal joint. These three techniques were then combined to determine the total potential tendon graft length obtainable using different approach. RESULTS: Only two different configurations were found. Type 1, a tendinous slip branched from the FHL to the FDL (62 of 64 feet). Type 2, a slip branched from the FHL to the FDL and another slip from the FDL to FHL (2 of 64). The average length of the FHL graft available from a single incision measured 5.08 cm (range 3.32-10.35, SD = 1.09), double incision technique measured 6.72 cm (range 4.69-12.09, SD = 1.03), and minimally invasive incision measured 17.49 cm (range 13.51-20.52, SD = 1.80). The difference between the lengths obtained from these three techniques was statistically significant (p < 0.001). CONCLUSION: The absence of no attachment and FDL tendon to the FHL between the two tendons in the foot may be more frequent than previously reported. Only two configurations of the anatomical relationship were found in this study. In over 96 % of the feet, a proximal to distal connection from the FHL to the FDL was found, which might contribute to the residual function of the lesser toes after FDL transfer.

Reconstruction of great toe soft-tissue defect with the retrograde-flow medial pedis island flap.

BACKGROUND: Several investigators have reported their clinical experience with medial pedis flaps for reconstruction of soft-tissue defects of the distal forefoot. However, they had only a few reports where this flap was used to repair soft-tissue defects of the great toe. Thus, reconstruction of soft-tissue defects of the great toe remains a challenge in reconstructive surgery. The authors describe the use of the medial pedis island flap to cover this region. METHODS: This study was divided into two parts: an anatomic study and clinical application. In the anatomic study, 48 cadaveric feet were injected with latex, and then the main vessels distributed at the medial aspect of the foot were observed. Clinically, retrograde-flow medial pedis island flaps were harvested to cover the soft-tissue defects of the great toe in eight cases. RESULTS: An anatomic study revealed that the arterial circle under the first metatarsophalangeal joint and the arterial network on the surface of the abductor hallucis were responsible for the blood supply of the medial region of the foot. The diameter of the pedicle was great, and the pedicle was longer than previously reported. In terms of clinical application, all flaps were successful, without any significant complications. CONCLUSIONS: Using the arterial circle under the first metatarsophalangeal joint, the medial pedis island flap has a reliable retrograde blood supply. This flap should be considered as a preferential way of reconstructing soft-tissue defects of the great toe. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, V.

[Design and clinical application of surgical device for closed reduction of tibial fracture].

OBJECTIVE: To describe a surgical device for dosed reduction of tibial fracture and investigate its clinical effectiveness. METHODS: Between June 2010 and December 2012, 24 cases of tibial fractures were treated with intramedullary nailing using a surgical device for closed reduction. There were 18 males and 6 females with an average age of 40 years (range, 20-64 years). All fractures were closed. There were 3 proximal third fractures, 12 middle third fractures, and 9 distal third fractures. According to AO classification, 12 cases were classified as type A, 8 cases as type B, and 4 cases as type C. The mean time between injury and operation was 3 days (range, 1-12 days). The intraoperative fluoroscopy frequency to confirm closed reduction and guide wire passing the fracture site, and the duration between fracture reduction and nail insertion were recorded. The injured limb alignment and fracture angular deformity were measured as described by Freedman et al. The fuction of affected limb was estimated by Johner-Wruhs criteria. RESULTS: Closed reduction was successfully performed in 24 patients. The mean fluoroscopy frequency to confirm closed reduction was 3 (range, 2-5). The fluoroscopy frequency to confirm guide wire passing the fracture site was 2. The mean duration between fracture reduction and nail insertion was 30 minutes (range, 20-42 minutes). No intraoperative or postoperative complication occurred, such as infection, vessel and nerve injuries. All incisions healed by first intention. Seventeen patients were followed up 6-16 months (mean, 10 months). Radiographic evidence showed that bridging callous was observed at 2-4 months (mean, 2.5 months). The injured limb alignment was normal on anteroposterial and lateral radiographs at 5 months postoperatively, no malalignment and obvious angular deformity was observed. The internal fixator had good position. According to Johner-Wruhs criteria for evaluation of the affected limb function, the results were excellent in 12 cases and good in 5 cases with an excellent and good rate of 100%. CONCLUSION: The surgical device for closed reduction of tibial fracture is simple and easy to use, and has good effectiveness combined with intramedullary nailing.

[Cause of micromotion in distal femoral prosthesis].

OBJECTIVE: To investigate possible causes of micromotion in distal femoral prosthesis. METHODS: Based on the assumption that the femur and prosthesis were considered as concentric cylinders with completely bonded interface, a theoretical model simulating the interfacial stress transfer was established. The distributions of the interfacial shear and radial stresses with the changing of z were obtained through mathematics and mechanics deducing. RESULTS: The maximum interfacial shear stress occurred at the position of z=0, namely, the cross section of the femur neck. The interfacial shear stress sharply decreased with the increasing of z and came to nearly zero at the range of z> 0.1 m. While the interfacial radial stress increased with the increasing of z,at the range of z >0.05 m it was constant and reached the maximum. CONCLUSION: The micromotion in distal prosthesis is caused by the interfacial radial stress.