| Objective:To explore the indication and observe short-term and mid-term clinical outcome of the medial Oxford III mobile bearing unicompartmental knee arthroplasty through a minimal invasive approach for the patients with osteoarthritis of the knee. To explore the early and midterm clinical outcomes of combined Oxford unicompartmental knee arthroplasty(UKA) and anterior cruciate ligament(ACL) reconstruction for the patients presenting ACL deficiency and isolated osteoarthritis(OA) of the medial compartment. Methods:1.A retrospective observational study of the clinical outcomes from May 2006 to May 2008 has been done on 30 knees in 21 patients after receiving the UKR with the mobile bearing Oxford III prosthesis. All patients were evaluated pre and post-operatively using X-ray image, the Knee Society Score(KSS) and the WOMAC osteoarthritis index and examined the ROM and the varus deformity of the knee with osteoarthritis. Paired t test was performed(using the SPSS12.0 software).2. From January 2006 to June 2010, 442 patients(485 knees) were included into the study. All patients were treated by MIA-UKR with the mobile bearing Oxford phrase III prosthesis. Plain radiographs in the antero-posterior and lateral view were routinely performed pre and post-operation. Stress radiographs in valgus were additionally available in order to verify the well-preserved lateral compartment. The varus deformity of the knee prior to surgery and the valgus degree after surgery were measured and recorded. Clinical evaluations include Knee Society Score(KSS-clinical score; KSS-function score), WOMAC osteoarthritis index and VAS.3. From Feberery 2006 to Feberery 2014, thirty-two patients with knee OA and deficient ACL were included into the study. All the patients who complained of pain at the medial compartment of knee and felt unstable of the knee were treated by combined Oxford UKA and ACL reconstruction. The mean age of the patients was 50 years old(41-63 years old).There were 12 males and 20 females, 17 left knees and 15 right knees in the group. There were 27 patients with the primary ACL old injury and secondary OA, 5 patients with primary OA and acute ACL injury. The main causes of the ACL injury were sports injury and traffic injury. The leg alignment showed 3.1±0.6°of varus deformity prior to surgery by the plain radiographs in the antero-posterior view. Results:In the short-term study of UKA, the average follow-up time was(17±3.6)months. The mean operation time was(83±12.9)minutes and the mean hospital stay was(9.3±2.0)days. No patient had the complication of infection, thrombosis, mobile bearing dislocation and so on. The loss of ROM and flexion of the operated knee was not significant. The average femorotibial angle(FTA) decreased from(182.2 ± 4.3)° preoperatively to(177.2 ± 3.5)° postoperatively in the anterioposterior view of X-ray, and the mean rectified varus deformity angle was(5.0 ± 2.6)°. The KSS Clinical Score and Function Score were improved from average 44.3 ± 3.7 and 54.1 ± 5.1 to 93.6 ± 3.4 and 92.4 ± 2.5 respectively. The WOMAC Score was average 48.2 ± 4.2 preoperatively, 13.2 ± 2.4 at the last evaluation. Statistically significant differences were found pre and post-operatively from the aforementioned evaluation criterions(P<0.05).While in the mid-term group, four hundreds and two patients completed the whole follow-up, 40 patients(45 knees) were lost. The average follow-up time was(73±1.9)months. The mean length of the incisions of the patients fulfilled the follow-up was(5.0±0.2)cm. No patient had the complication of fracture during operation, and there was no patient with the complications such as collapse of tibial plateau, infection, thrombosis, and aseptic loose. There were 4 patients with the complication of mobile bearing dislocation, 3 of them got the operation of changing mobile bearing and one patient had the operation of revision to TKR. Another 1 patient had the side injury of MCL when doing the operation of UKR. Besides, 2 patients had to get the arthroscopic operation 1 month post-operation as a result of leaving bone cement in the joint cavity when doing UKR. There were another 2 patients who still had moderate pain in the operated knee after operation. The average femorotibial angle(FTA) decreased from(183.6 ± 5.1)° preoperatively to(174.3 ± 4.2)° postoperatively in the coronal view of X-ray, and the mean rectified varus deformity angle was(9.3 ± 1.2)°. The KSS Clinical Score and Function Score were improved from average 42.4 ± 2.9 and 53.5 ± 3.8 to 92.9 ± 3.8 and 93.5 ± 4.0 respectively. The WOMAC Score was average 47.5 ± 3.1 preoperatively, 12.3 ± 1.5 at the last evaluation. The VAS dropped from 7.78±1.85 preoperatively to 1.56±0.23 postoperatively. Statistically significant differences were found pre and post-operatively from the aforementioned evaluation criterions(P<0.05).As for the combination group, all cuts healed by first intention. All the patients were followed up for 55±8 months. There were 2 patients with the complication of mobile bearing dislocation which happened at about 2 years after the first operations, both of them got the operation of replacing much thicker mobile bearings and satisfied with the results. The leg alignment showed 4.0±0.7°of valgus at the last follow up after surgery. There was no patient with the incidence of loosening of the prosthesis. Physiological radiolucent lines around the tibial component of less than 1 mm were seen in 10 patients. The Oxford Knee Score(OKS), Knee Society Score(KSS-clinical score; KSS-function score) and Tegner activity score at the last follow up improved significantly after surgery(P<0.01). The mean ROM of the operated knee was 123.5±2.8°at the last follow-up. The posterior slope of the tibial component was 3.9±1.2° when measured at the last follow up. A significant correlation was found between them according to the Pearson’s correlation(r=0.392, P=0.031). Conclusion:The short-term and mid-term clinical outcomes of medial Oxford III mobile bearing UKR through a minimally invasive approach are ideal, and it is a good therapy choice for the patients with medial osteoarthritis of the knee. The early and midterm clinical data have shown that combined surgery of UKA and ACL reconstruction has revealed promising results. However, long-term follow-up studies should be done in these patients.
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