ABSTRACT
Objective To perform finite element analysis on a novel motion mode hinged knee prosthesis, and investigate the method of wear simulation on hinged prosthesis and the influence of motion mode on wear of the prosthesis. Methods Based on the finite element model of contact stress on spherical axis prosthesis, the finite element model of wear was established according to Archard wear theory. The kinematics data during different motions were input as loading condition to simulate mechanical environment of the knee arthroplasty in physiological activities. The wear results of spherical axis prosthesis were studied. Results For tibial insert, the average and maximum contact stresses during upstairs and downstairs climbing were higher than those during walking, and the cumulative wear volume during upstairs climbing was larger than that during downstairs climbing and walking. The wear mainly occurred on lower surface of tibial insert during all 3 motions. For rotating bushing, there was only a short period of contact and wear during walking, and the cumulative wear was 0. 19 mm3. Conclusions The spherical axis motion of hinged knee prosthesis can improve the mechanical environment of knee, reduce the wear of rotating bushing, and prolong the prosthesis survival. The finite element simulation can predict the wear of hinged prosthesis effectively, and provide the theoretical basis for design and improvement of the prosthesis.
ABSTRACT
BACKGROUND:The treatment method of tibial avulsion fractures of anterior cruciate ligament is varied;each has its advantages. OBJECTIVE:To investigate the methods and clinical effects of the treatment of avulsion fractures of tibial insertion of anterior cruciate ligament by the means of making two decussate lines and four strands of non-absorbable Arthrex sutures passing through two bone tunnels combined with pushlock free knotting anchor under arthroscopy. METHODS:From December 2014 to November 2015, 23 cases of avulsion fractures of tibial insertion of anterior cruciate ligament were treated in the Second Hospital of Inner Mongolia Medical University. Under the arthroscopy, avulsed fracture was fixed in tibial intercondylar eminence by the means of making two decussate lines of Arthrex sutures passing through. At the same time, pushlock free knotting anchor beside tibial tubercle provided a tightening of tension for Arthrex sutures, which could strengthen the fixation of avulsion fracture blocks. Knee joint Lysholm and Tegner scores were fol owed up. Knee stability was evaluated by anterior drawer test and Lachman test. Postoperative reset and healing were evaluated with X-ray films. RESULTS AND CONCLUSION:(1) Al 23 patients were fol owed up for 6 months to 1 year. (2) Lysholm scale of the knee function was (47.31±6.16) preoperatively and (94.69±1.28) postoperatively (P<0.05). Tegner score was (3.14±1.58) preoperatively and (7.74±1.69) postoperatively (P<0.05). (3) Lachman test of al cases was negative. X-ray films demonstrated that fracture healing was good. There was no repeated swel ing or cross locking of the joint. The knee was not limited by flexion or extension. No infection or deep venous thrombosis of lower extremity occurred. (4) The method of Arthrex sutures passing through two bone tunnels combined with pushlock free knotting anchor under arthroscopy has the advantages of minimal y invasive, simple operation, reliable fixation, no metal implants and satisfactory result to treat the tibial intercondylar eminence fracture of anterior cruciate ligament.
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BACKGROUND:Alogeneic tendon has been frequently used to reconstruct the anterior cruciate ligament. However, there is a lack of middle- and long-term clinical evaluation. OBJECTIVE:To evaluate the middle- and long-term curative effect of alogeneic tendon reconstruction of the anterior cruciate ligament under arthroscopy. METHODS:Twenty-five patients with anterior cruciate ligament injury under alogeneic tendon transplantation were reviewed retrospectively. They were al folowed up for 3 years or more. The clinical outcomes were evaluated and compared using Lyshlom score scale, IKDC2000 and Tegner score scale. RESULTS AND CONCLUSION:Al the patients were folowed up. Lysholm scale scores on the knee function, Tegner scores and IKDC scores were significantly increased after transplantation (P < 0.05). No complications of infection and compartment syndrome occurred. Symptoms were relieved and the function of knee joint was improved. There was one case weakly positive for anterior drawer test. Both Lachman test and pivot shift test showed negative signs. Overal, the reconstruction of anterior cruciate ligament with alogeneic tendon has less trauma and complications, with good middle-term efficacy.
ABSTRACT
BACKGROUND:Autologous hamstring tendon reconstruction of the medial patel ofemoral ligament is now more popular surgical procedure. OBJECTIVE:To study the clinical mid-term outcomes of isolated medial patel ofemoral ligament reconstruction for recurrent lateral patel ar dislocation. METHODS:The clinical data of 24 patients (25 knees) undergoing medial patel ofemoral ligament reconstruction for recurrent patel ar dislocation from September 2006 to September 2009 were retrospectively studied. Clinical, functional, and CT outcomes were assessed at an average of 3.1 years after surgery (range, 2-5 years), using recurrent instability as the primary end point. RESULTS AND CONCLUSION:The success rate of medial patel ofemoral ligament reconstruction for preventing recurrent dislocations was 92%. Two patients (8%) experienced a recurrent lateral patel ar dislocation, and required a reoperation. At final fol ow-up, the mean IKDC, Tenger and Lycholm scores were significantly higher than those before operation (P<0.01). Reconstruction of the medial patel ofemoral ligament for recurrent patel ar instability is a minimal y invasive operation and has a number of benefits. The mid-term clinical outcome was satisfactory.