| Objective To explore the early outcome of unicompartmental knee arthroplasty for anteromedial osteoarthritis of the knee, and assess the radiological difference before and after operation. Explore possible ways to improve the surgical skills.Methods We conducted a retrospective study of 34 medial UKAs in 33 patients between march,2014 and October,2015, with a mean follow-up of 12.3 (5.0-24.0)months, during which time there was only one patient lost to follow-up. The patients consisted of 15 males and 17 females with a mean age of 62.1 years (47-83 years), along with a mean BM1 of 26.74 kg/m2 at surgery. We recorded the following radiographic parameters:femorotibial angle (FTA), varus angle of knee joint, the joint line convergence angle (JLCA), slope of the tibial implant or tibial plateau. The American Knee Society Knee Score (KSS) and range of knee motion were used to assess clinical outcome.Results During the follow-up, the midpoint of which is 11 months (5-24months), all the surgical sites got healed well, and none of the patients had complications such as infection, deep vein thrombosis, mal-position of prosthesis and loosening except that only one dislocation of Polyethylene tibial insert occurred, which was replaced by a thicker one.1. The average clinical Knee Society score increased from 58.5 before surgery to 91.9 and function score from 49.1 to 90. The difference of clinical score between pre-operation and post-operation was significant(P<0.05), so was the function score. The excellent and good rates of clinical score and function score were 100% and 97%, respectively; 2. The mean range of motion improved from 100.0°pre to 120.0° postoperatively, the difference of which is statistically significant(P<0.05); 3. The mean femorotibial angle improved from-0.6°to 3.4°, obviously the corrected angle being 4.0°, which was also significantly different(P<0.05); 4. The mean varus angle of knee joint decreased an average of 4.9° from a mean value of 7.6°before UKA, with statistically significance(P<0.05), making the varus angle of knee be 2.5°; 5. the joint line convergence angle:dropped from a mean angle of 1.9°before surgery to 1.5 °after surgery, which showed statiscally significance; 6. Posterior slope angle of the tibial implant or tibial plateau:the value before UKA was 5.6°in the endomarrow way, and 8.6° in the ectomarrow way. Similarly, the value after UKA was 8.1°and 11.7°, respectively. There was significant difference between these two methods(P<0.05), and so is the difference between pre-operation and post-operation in both methods(P<0.05).Conclusion Oxford phrase Ⅱ unicompartmental knee arthroplasty can correct the line of force to some extent. And the short-term result is excellent, whereas the long-term outcome needs further follow-up. Proper patient selection and suitable implant designs are critical to the success of UKA. Morever, use bony marks for double check of component position, correct deformity in a moderate and balanced way, individually restore the physiological state of line of force and soft tissue balance as much as possible, all these further contributing to a better outcome of UKA. Finally the keenly insightful understanding of the official surgical steps, along with the flexible grasp of UKA operating skills is the key to successful operation. |
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