Despite good long-term results of primary total knee arthroplasty, it is a commonly accepted aim to stave off joint replacement as long as possible, particularly in younger patients. In this situation the surgeon has to make a careful decision whether an arthroscopic procedure will be promising, a corrective osteotomy may be sensible or a joint replacement due to the patient's age is acceptable. High tibial osteotomy had become increasingly popular by use of the opened wedge technique combined with locking compression plates fixation in the past decades while it has been replaced step by step by total knee arthroplasty. In spite of this fact the German national agency of quality management (BQS) showed that the number of total knee replacements in Germany increased from 90 000 in 2003 to 146 000 in 2008. The share of unicompartmental knee replacements in this period doubled from 5.3 % to almost 10 %. The aim of the present study was to inquire current data regarding particular surgical treatment concepts of unicompartmental knee arthritis in Germany.
In a nationwide anonymous survey in May 2009 220 departments of orthopaedics and 230 departments of trauma surgery were asked about their treatment strategies in unicompartmental knee arthritis in middle-aged patients (30 to 60 years) with unilateral Outerbridge grade III-IV lesions. Overall 46 questions in 6 subject areas (structure of the department, number of treated patients, surgical methods, anaesthesiological procedures, perioperative management, postoperative treatment) were posed. With regard to the item "operative treatment" we asked for the importance of arthroscopic procedures, corrective osteotomies and different procedures of joint replacement. The interpretation was done with invariant data analysis by indication of numerical frequency and percentage distribution of selected options.
Questionnaires were returned by 51.1 % of the surveyed departments. This represents a total number of 76,028 procedures in unicompartmental knee arthritis in middle-aged patients. First of all, arthroscopic procedures were applied (50.4 %), followed by knee replacements (43.4 %, of which 87.3 % were total knee replacements, 12.3 % unicompartmental knee replacements and 0.4 % tibial hemiarthroplasties) and corrective osteotomies (6.1 %). In 59.8 % of the 38,376 arthroscopic procedures a microfracturing and in 28.2 % an abrasion arthroplasty was done. Most of the corrective osteotomies were performed at the proximal tibia (90.9 %) using an open wedge technique (73 %) and internal fixation with locking compression plates (72 %). 75.2 % of the responders performed cemented unicompartmental arthroplasties (97.8 %) with an average number of 23.2 per year. 43.4 % believe that bicompartmental arthroplasty in case of additional affection of the femoropatellar joint is an option and 22.6 % believe in the expected advantages of patient-specific unicompartmental implants. Total knee arthroplasties are performed with an average of 197.4 per year, most frequently using the free-hand technique (85.5 %) and medial-parapatellar approach (82 %). Interpositional knee devices were only used in 9.1 % of responding departments with an average number of 6.6 per year. Only procedures with low difficulty level such as arthroscopies were done by residents in a higher number (16.9 %). Procedures with higher difficulty level were mainly done by consultants, senior or chief surgeons.
In total, arthroscopic procedures still play an essential role in the treatment of unicompartmental knee arthritis prior to joint replacement. Total knee arthroplasty was preferred even though the number of unicompartmental knee replacements was only slightly increasing. Periarticular corrective osteotomies have gained in importance since the introduction of locking compression plates. Interpositional knee devices play a minor role in the treatment of unilateral knee arthritis in Germany.