Anterior knee pain continues to be a major problem following total knee arthroplasty (TKA). Patellofemoral joint is closely associated to the occurrence of the anterior knee pain, so it is also called patellofemoral joint pain. Overstuff of patellofemoral joint and patella maltracking are the main factors for anterior part of the post-operative pain. They are resulted from the change of native morphology and Q angle of patellofemoral joint after operation. Instead of non-modifiable patients' congenital and genetic factors, they are mainly related to the improper surgical techniques and the mismatch between prostheses and native patellofemoral morphology. The reason of the mismatch is that the prosthesis is unable to cover all kinds of differences of the patellofemoral morphology among races and genders. In addition, some surgical techniques, including patellar replacement, circumpatellar denervation, femoral and patellar prostheses location, and the selection of the type of prosthesis, also affect the occurrence of anterior knee pain. The above mentioned factors may eventually lead to excessive and uneven distribution of the patella-femoral loads, which would compress and simulate the peripheral nerves around the joint. Ultimately, they result in the anterior knee pain. Therefore, the following effective strategies could lead to relief anterior knee pain and improve patients overall satisfaction after TKA, including improvements of prostheses design, patellar resurfacing, circumpatellar denervation, infrapatellar fat padpreservation or using mobile-bearing rotating-platform.

Objective:To explore the clinical effects of a single stage reconstruction and revascularization using a free Flow-through chimeric anterolateral thigh perforator (ALTP) flap in Gustillo III C limb injuries.Methods:From January, 2010 to December, 2017, 17 patients with Gustillo III C injury of extremities were repaired with Flow-through chimeric ALTP in emergency surgeries. The patients were 16 males and 1 female with mean age of 32.4 (19-55) years. The size of wounds ranged from 16 cm×8 cm-45 cm×30 cm. The injured arteries were Flow-through anastomosed with the descending branch of the lateral circumflex femoral artery to regain blood flow. The deep dead space was filled with vastus lateralis flap, and the skin flap and fascia flap were used for superficial covering. The donor site was closed directly in 6 patients, simultaneous skin grafts were applied in 11 patients.Results:The followed-up time ranged 5 to 60 (average 21.8) months, and conducted by clinic visits and by telephone or WeChat interviews. Fifteen flaps survived, and 2 flaps failed with limb amputated. Six patients were repaired with skin and fascia flaps and 11 patients received flaps comprising the skin, fascia and vastus lateralis muscle. Four flaps healed in stage I. Partial necrosis were observed in 11 flaps. Of which, 1 healed by change of dressing and 10 healed by skin grafting. No complications occurred in donor site in all patients.Conclusion:The Flow-through chimeric ALTP flap can be used in stage I reconstruction of the blood supply of limbs and meanwhile achieve the 3-D repair of defects. It is one of the reliable methods in the reconstruction of Gustillo III C injuries in the extremities.