Bone defects,a challenge in orthopedics,are mostly caused by severe trauma,bone tumor and bone infection.Their chief treatments include bone graft,distraction osteogenesis and Masquelet technique.Compared with other treatments,Masquelet technique is simpler and causes fewer complications,especially for infectious defects.In the first stage of Masquelet technique,a bone defect is filled with bone cement.The spacer most commonly used is polymethylmethacrylate(PMMA).PMMA can form induced membrane rich in blood vessels and bioactive components promoting osteogenesis,but it is not biodegradable,lacks bone conductibility,has an obvious thermal effect during operation,and is hard to remove in the second phase of Masquelet technique.Calcium sulfate and calcium phosphate bone cement are biodegradable materials which overcome the defects of PMMA due to their biological absorbability,bone conduction and bone inducement.It is possible for them to replace PMMA in Masquelet technique,but their poor mechanical strength limits their application.There is clinical evidence showing that calcium sulfate bone cement can form obvious induced membrane.As calcium silicate cement can also form a layer of fibrous tissue around the shell,it may be applied in orthopaedic surgery after improvement as a potential filling agent.A structure like induced membrane can form around a silicone prosthesis,and it functions similarly as induced membrane around PMMA and is more resistant to a radiation environment.Silicone has obvious advantages over PMMA after resection of bone tumor.Spacers used in the first stage of Masquelet technique have important effects on formation process and quality of induced membranes.By comparing membranes induced by different types of spacer,we can know more about the effects of spacers on induced membranes in the first stage of Masquelet technique and thus discover the most suitable spacers good for fracture healing and membrane formation.

Objective To evaluate the induced membrane technique (Masquelet technique) used for restoration of long bone defects of infected tibia.Methods This retrospective study evaluated 44 patients with long bone defect of infected tibia who had been treated at Department of Orthopedics,The Second Affiliated Hospital by the induced membrane technique between January 2004 and January 2017.They were 31 males and 13 females,aged from 18 to 71 years (mean,43.7 years).Of them,17 were complicated with diabetes,13 with primary hypertension,and 12 with more than two basic diseases.Their bone defects ranged from 6 to 17 cm (average,11 cm).Their postoperative fracture healing and complications were observed.Results This cohort received from 2 to 5 operations on average (average,3.7 operations).All the patents obtained bony union after 9 to 13 months (average,11.3 months).Their follow-ups ranged from 16 months to 11 years (average,3.1 years).Nineteen complications related to the surgery occurred in 15 cases.Skin healing problem after implantation of bone cement was found in 5 cases which called for operative intervention,infection relapsed in 8 patients after the first phase of cement implantation which necessitated further surgical debridement for successful management,local haematoma appeared after bone grafting in one case of 17 cm bone defect,implant failure occurred in one case,leg length discrepancy larger than 2 cm was observed in 3 cases,and a discharging sinus developed in one case 2 years after successful healing of a tibial defect.Conclusions The induced membrane technique appears to be a good alternative management for large tibial defects secondary to infection.The technique should be considered in the surgeon's armamentarium and patients conditions as it is effective and associated with a low rate of complications.

Objective To explore the treatment methods and prognosis of early infection and delayed infection after intramedullary nail fixation.Methods Data of 22 cases of postoperative infections after intramedullary nail from January 2013 to August 2017 were retrospectively analyzed.There were 18 males and 4 females aged from 20 to 72 years old,with an average age of 46.8 years.14 cases were tibias and 8 cases were femurs.In the early infection group,6 cases showed swelling,heat and pain in the affected area with drainage and pus.In the late infection group,12 cases showed sinus formation and 4 cases showed no sinus tract.According to whether the infection occurred within six weeks,it was divided into early infection and delayed infection groups.Of 6 patients in early infection group,there was 1 case of septic shock which underwent removal of intramedullary nails,debridement and antibiotic bone cement stick implantation.5 cases were retained intramedullary nail and underwent local debridement treatment.Late infection occurred in 16 patients.One patient with tibia infection was given partial dressing to heal the fracture.Then the intramedullary nail was removed and intramedullary debridement was performed.Two patients with poor general condition,the intramedullary nails were removed and debridement was performed.Calcium sulphate cement was implanted and fixed with external fixation.The remaining 13 cases were treated with debridement and antibiotic cement stick implantation.We compared the differences between early and late infections of internal fixation,infection control,fracture healing,and secondary fracture fixation.Results Of the 6 patients with early infection,1 patient with septic shock removed intramedullary nails to control infection.After infection controlled,the fracture was treated with intramedullary nailing.Of the 5 patients with retained intramedullary nails,2 patients' infection were controlled and 3 were uncontrolled.After removal of the intramedullary nails the infection was control.The success rate of retaining intramedullary nails was 33.3％ (2/6).Late infection occurred in 16 cases and infection was all controlled.The fractures healed in 22 patients.The fracture healing time of 6 patients with early infection was 2-6 months,with an average of 3.67±2.08 months.The fracture healing time of 16 patients with late infection was 2-4 months (average 3.2±0.79) months.Conclusion Patients with early bone infections after femoral and tibial intramedullary nail surgery may attempt debridement therapy with retained intramedullary nails,but the failure rate is high.If the intramedullary nail fails to remain,follow the treatment of patients with delayed bone infection.For patients with delayed bone infection,because the fracture has not yet healed,thorough debridement is used after the removal of internal fixation,then calcium sulfate or antibiotic bone cement stick should be implanted and fixed with external fixation.For the second phase,we may choose plate,intramedullary nail or external fixation to fix the fractures according to the soft tissue condition.All of the fixation methods could provide good fracture healing.

Objective:To investigate the efficacy of internal fixation maintenance after fracture-related infection (FRI).Methods:Retrospectively analyzed were the data of 81 patients with deep FRI after 6 weeks of internal fixation who had been treated with hardware maintenance at Department of Orthopedics, The Second Hospital Affiliated to School of Medicine, Zhejiang University between 2013 and 2021. They were 61 males and 20 females, aged from 11 to 73 years (average, 11 years). After admission, the patients received bacterial culture, thorough debridement, negative pressure suction, soft tissue repair, and local and intravenous antibiotics. If a joint was affected by FRI, its cavity was cleaned and drained. Infection control and fracture healing were regularly observed in all patients. A treatment was considered successful when the internal fixation was maintained until fracture union, and considered as unsuccessful when the internal fixation was removed before fracture union. Risk factors associated with treatment failure were identified from gender, age, smoking, diabetes, fracture type, methicillin-resistant Staphylococcus aureus (MRSA) infection, methicillin-susceptible staphylococcus (MSSA) infection, Pseudomonas aeruginosa infection, Escherichia coli infection, infection by two kinds of bacteria, negative bacterial culture, early infection (within 2 weeks) and local use of antibiotics.Results:All patients were followed up for an average of 30 months (from 6 to 84 months). Fracture union was achieved in 62 (76.5%) patients with infection control and internal fixation retained. Masquelet technique was used to treat bone defects in 2 patients; a muscle flap or skin flap was used to reconstruct soft tissue coverage in 11 cases; fracture union was achieved by antibiotics and dressing changes in 2 patients with sinus tract. Amputation was performed in one unsuccessful case due to uncontrollable infection, and internal fixation was changed to external fixation in the other 18 unsuccessful cases, of which 3 achieved final bone union after application of Masquelet technique, 7 achieved final bone union after application of bone transfer technique, and 3 achieved soft tissue coverage after reconstruction with flap technique. Pseudomonas aeruginosa infection, open fractures and FRI for more than 2 weeks were high risk factors for failure in internal fixation maintenance ( P<0.05). Conclusions:If internal fixation is still stable and effective, hardware maintenance should be tried first in the patients with FRI within 6 weeks after fracture internal fixation. Muscle flap or skin flap surgery should be performed as soon as possible to effectively control infection and promote fracture union in the patients with soft tissue defects after thorough and effective debridement. History of open fracture, Pseudomonas aeruginosa infection, and FRI for over 2 weeks may be risk factors for failure in internal fixation maintenance.