[Treatment of avulsion fracture of inferior pole of patella with improved angle of anchor and double pulley technique].

OBJECTIVE: To evaluate the angle of modified anchor nail placement and the curative effect of double pulley technology for the treatment of extreme avulsion fracture of lower patella. METHODS: From December 2015 to December 2018, a total of 22 patients(10 males and 12 females) with avulsion fracture of the inferior pole of patella were retrospectively analyzed. The average age was (44.00±15.24) years old(range, 19 to 70 years). All patients were treated with modified anchor angle and double pulley technique. The range of motion(ROM) and Bostman score system were used to evaluate the functional recovery of knee joint. RESULTS: All 22 cases were followed up with an average of (30.86±8.00) weeks (18 to 46 weeks). At the last follow-up, ROM of the affected knee was (130.82±4.69) °, and the contralateral knee was (133.23 ± 3.15) °, there was no significant difference between two groups (P>0.05). The average Bostman score was (28.45±1.41) scores, 18 cases were excellent results, 4 cases were good. CONCLUSION: Improved anchor placement angle and double pulley technique for treatment of extreme avulsion fracture of lower patella is easy to operate, with satisfactory curative effect and good recovery of knee joint function.

Weak link of tendon-bone healing and a control experiment to promote healing.

OBJECTIVE: This study aims to observe the mechanical weak point and histological features of tendon-bone interface after anterior cruciate ligament reconstructive surgery and to explore the tendon-bone healing effects of the platelet-rich gel (PRG) + deproteinized bone (DPB) compound. METHODS: A total of 48 New Zealand white rabbits were randomly divided into normal group, model (without embedding), experimental (embedded with the PRG + DPB compound), and control (embedded with DPB) groups. The rabbits were executed at 2, 4, 8, and 12 weeks after the operation. Then, micro-computed tomography scan and uniaxial tensile test were conducted. The fractured specimens were subjected to histological observation. RESULTS: At 4, 8, and 12 weeks after the operation, the bone density of the tendon-bone bound section of the experimental group was higher than that of the other groups (P < 0.05). At 4 and 8 weeks, the maximum tensile load of the experimental group was obviously higher than that of the control and model groups (P < 0.05). Histological observation indicated that the tendon-bone interface in the experimental group had more cartilage and bone tissue growing toward the internal tendon, but the fracture layer mainly occurred in the non-ankylosed part. CONCLUSION: The mechanical weak point of the early tendon-bone interface was in the immature fibrous tissue. The PRG + DPB compound can effectively trigger tendon-bone healing by promoting the maturation and ossification of the tendon-bone tissue. This compound improved the tensile strength of the healing interface and reduced bone tunnel enlargement.