Seventy-six patients with septic arthritis (78 affected joints) were treated with a combination of arthroscopic irrigation, debridement, and antibiotic therapy according to the tested bacterial sensitivity. There were 62 knee, 10 shoulder, 5 ankle joints, and 1 hip joint. No antibiotics were added to the irrigating solution. The arthroscopic and radiological stage of infection, treatment, and outcome in these patients was analyzed. The patients were classified into three groups according to initial stage of joint infection (stage I: 21 patients, 22 joints; stage II: 43 patients, 44 joints; stage III: 12 patients, 12 joints). Causes of infection were: hematogenous dissemination in 54%, postoperative wound infection in 28% (17% after open, 11% after arthroscopic procedures). Other causes were: 10% intra-articular steroid injections, 3% diagnostic punctures, and 3% open traumatic injury of the joint. In 78% of the infected joints the causative organism could be identified: Staphylococcus aureus was the most common organism found (42%), followed by streptococci (15%), pneumococci (6%), Escherichia coli (4%), Staphylococcus epidermidis (3%), Borrelia burgdorferi (3%), and others in 5%. In the stage I group only one patient needed repeated arthroscopic irrigation, in the stage II group 52%, and in the stage III group 75%. Open revision for eradication of the infection was necessary in one joint with stage II and in two joints with stage III infection (3%). Two joints of the stage III group needed additional surgery after successful treatment of the infection. The combination of arthroscopic irrigation and systemic antibiotic therapy was able to cure 91% of the affected joints. Open revision was necessary in 4% of joints. The number of arthroscopic procedures and the efficacy of treatment depended on the initial stage of the infection. It is concluded that an arthroscopic staging of the initial joint infection has prognostic and therapeutic consequences.

The Core Outcome Measures Index (COMI) is a short, multidimensional outcome instrument, with excellent psychometric properties, that has been recommended for use in monitoring the outcome of spinal surgery from the patient's perspective. This study examined the feasibility of implementation of COMI and its performance in clinical practice within a large Spine Centre. Beginning in March 2004, all patients undergoing spine surgery in our Spine Centre (1,000-1,200 patients/year) were asked to complete the COMI before and 3, 12 and 24 months after surgery. The COMI has one question each on back (neck) pain intensity, leg/buttock (arm/shoulder) pain intensity, function, symptom-specific well being, general quality of life, work disability and social disability, scored as a 0-10 index. At follow-up, patients also rated the global effectiveness of surgery, and their satisfaction with their treatment in the hospital, on a five-point Likert scale. After some fine-tuning of the method of administration, completion rates for the pre-op COMI improved from 78% in the first year of operation to 92% in subsequent years (non-response was mainly due to emergencies or language or age issues). Effective completion rates at 3, 12 and 24-month follow-up were 94, 92 and 88%, respectively. The 12-month global outcomes (from N = 3,056 patients) were operation helped a lot, 1,417 (46.4%); helped, 860 (28.1%); helped only little, 454 (14.9%); did not help, 272 (8.9%); made things worse, 53 (1.7%). The mean reductions in COMI score for each of these categories were 5.4 (SD2.5); 3.1 (SD2.2); 1.3 (SD1.7); 0.5 (SD2.2) and -0.7 (SD2.2), respectively, yielding respective standardised response mean values ("effect sizes") for each outcome category of 2.2, 1.4, 0.8, 0.2 and 0.3, respectively. The questionnaire was feasible to implement on a prospective basis in routine practice, and was as responsive as many longer spine outcome questionnaires. The shortness of the COMI and its multidimensional nature make it an attractive option to comprehensively assess all patients within a given Spine Centre and hence avoid selection bias in reporting outcomes.

The Core Outcome Measures Index (COMI) is a reliable and valid instrument for assessing multidimensional outcome in spine surgery. The minimal clinically important score-difference (MCID) for improvement (MCID imp ) was determined in one of the original research studies validating the instrument, but has never been confirmed in routine clinical practice. Further, the MCID for deterioration (MCID det ) has never been investigated; indeed, this needs very large sample sizes to obtain sufficient cases with worsening. This study examined the MCIDs of the COMI in routine clinical practice. All patients undergoing surgery in our Spine Center since February 2004 were asked to complete the COMI before and 12 months after surgery. The COMI has one question each on back (neck) pain intensity, leg/buttock (arm/shoulder) pain intensity, function, symptom-specific well-being, general quality of life, work disability, and social disability, scored as a 0-10 index. At follow-up, patients also rated the global effectiveness of surgery, on a 5-point Likert scale. This was used as the external criterion (''anchor'') in receiver operating characteristics (ROC) analyses to derive cut-off scores for individual improvement and deterioration. Twelve-month follow-up questionnaires were returned by 3,056 (92%) patients. The group mean COMI score change for patients declaring that the ''operation helped'' was a reduction of 3.1 points; the corresponding value for those whom it ''did not help'' was a reduction of 0.5 points. The group MCID imp was hence 2.6 points reduction; the corresponding group MCID det was 1.2 points increase (0.5 minus -0.7). The area under the ROC curve was 0.88 for MCID imp and 0.89 for MCID det (both P \ 0.0001), indicating that the COMI had good discriminative ability. The cut-offs for individual improvement and deterioration, respectively, were C2.2 points decrease (sensitivity 81%, specificity 83%) and C0.3 points increase (sensitivity 83%, specificity 88%). The MCID imp score of 2.2 points was similar to that reported in the original study (2-3 points, depending on external criterion used). The MCID det suggested that the COMI is less responsive to deterioration than to improvement, a phenomenon also reported for other spine outcome instruments. This needs further investigation in even larger patient groups. The MCIDs provide essential information for both the planning (sample size) and interpretation of the results (clinical relevance) of future clinical studies using the COMI.

Overall, greater back pain relative to LP at baseline was associated with a significantly worse outcome after decompression. This finding seems intuitive, but has rarely been quantified in the many predictor studies conducted to date. Consideration of relative LBP and LP scores may assist in clinical decision-making and in establishing realistic patient expectations.