In last ten years U.K.R. number increased due to diffusion of M.I.S. concepts, new indications/tecniques and durable prosthetic models. Also the amount of revisions, performed for different reasons, has increased. Failures relate to planning and surgical errors, aseptic loosening, non treated or femoro patellar compartment degeneration, ligaments instability, P.E. wear, components ruptures, infections.

In our division in 1990–2003 we performed 136 U.K.R. revisions on 13 different implants with a prevalence of “fixed bearing” (79,40%) on “meniscal bearing” (20,60%). A classification withprevalence of failure causes, different from T.K.R.’s, is proposed. Revision procedure strongly depends on causes: “Uni”, “BiUni” or “Total” approach is possible. We present our experience and derived indications.

Aseptic loosening were treated differently depending on bone stock and on failure risk factors (ligament laxity, surgical osteotomic or axial errors, fixation defects) with a “Uni” revision or with a “Total”. Unicompartimental degeneration with a previous medial or lateral U.K.R. in good conditions may undergoes “BiUni” instead of “Total” only in absence of ligament laxity and femo-ropatellar symptomatic degeneration. Femoro-patellar degeneration needs a T.K.R. implant. We managed cases with macroscopic surgical errors (ostheotomy or component alignment) by using T.K.R. (stemmed and with auto-graft if needed) and U.K.R. revision. Failures due to varus-valgus instability were normally treated with T.K.R. (standard or stemmed) and with constrained T.K.R. (1 Reumatoid Arthritis case). We resolve P.E. debris failures in fixed bearing implants simply with a component change as we do in stress fractures (femur or “full poly” tibia). We treat infections with a 2 step procedure; for 2°step we used T.K.R. (standard or stemmed).

In conclusion U.K.R. revision is technically easier than TKR’s, bone stock defect may be fighted with auto graft and/or stems and in a selected amount of cases it’s possible to use U.K.R. orstandard T.K.R. with very similar long term results of first implants.

Aim of the study was to evaluate the recovery and short term results of simultaneous bilateral unicompartmental knee replacement in front of unilateral procedure.

Materials and methods: At the “Istituto Ortopedico Galeazzi”, in Milan, we performed 244 UKR in a 12 months period. Forty were sequential bilateral procedure. We compared two groups of patients: one bilateral sequential procedure (BPS), the other unilateral procedure (UP). Student t test has been used for statistical analysis.

Results: Blood transfusion: BSP 8 cases, and UP 5 cases. 90° active flexion: BSP 4,7 (2–6) days, and UP 3,5 (1–6) days. Stairs climbing: BSP 5,6 (4–8) days, and UP 4,9 (4–9) days. Hospital stay: BSP 12,4 (10–17) days, and UP 11,4 (5–19) days; p=0,045. Complications during the first month after surgery: BSP none, and UP 3 (1 wound redness, 2 urinary infection). From 6 to 18 months, KSS and function: BSP 53 (28–80) points, 61 (20–100) points; UP 51 (25–85) points, 66 (20–100) points; p=0,325 e p=0,133. Oxford self assessment were: BPS 26,57 and UP 23,54. No statistically significant differences were among groups.

Conclusions: This study shows bilateral procedure is safe, and allows recovery comparable to single knee procedure. Bilateral sequential unicompartmental procedure should be considered for bilateral arthritis of the knee.

Background: Unicompartmental knee arthroplasty was developed as an alternative to the finality of tricompartmental, total knee arthroplasty. Recent short-term and intermediate-term results show favorable results when compared to the first generation results reported in the 1970’s and early 1980’s. The purpose of this study was to report the long-term, single surgeon use of the Allegretto unicondylar knee prosthesis.

Methods: We evaluated 115 medial unicompartmental knee arthroplasties that were implanted by a single surgeon using the Allegretto prosthesis. The average age of the patients at the time of surgery was sixty-eight years. No patients were lost to follow-up. Nineteeen patients were unable to continue long-term office follow-up and were contacted by telephone. Thirty-four patients (thirtyfive knees, 30%) died from unrelated causes. None of the patients that died underwent revision of the index UKA. Thus there were sixty-one patients available for prospective clinical and radiographic evaluation beyond ten-years.

Results: The average time to follow-up for those patients available prospectively was 11.1 years (0.8 years; range, ten years to thirteen years). Clinical evaluations revealed an average pre-operative HSS score of fifty-four points which improved at the most recent post-operative follow-up to an average of ninety-three points. At the most recent average time to follow-up, the post-operative range of motion was assessed at an average of 0.3 degrees of extension through 124.4 degrees of flexion. Radiographically, no component showed evidence of loosening as defined as change in position of the components on serial radiographs. Twenty-one knees demonstrated radiolucencies less than 2 mm of thickness and none were progressive. The Kaplan-Meier survival analysis was calculated and showed a probability of survival of all UKA implants of 97% at thirteen years follow-up (standard error 0.04) with an end-point of revision or radiographic failure.

Conclusions: Provided correct patient selection and technical expertise, the Allegretto UKA system allows for the expected relief of pain, restoration of function and component survival in those patients with medial compartmental knee arthrosis through ten-years.

Aim: Endpoints that are more common than revision would be more valuable in survival analysis. Assessment of unicompartmental knee replacement (UKR) by patientñs own evaluation may be sensitive as for total knee replacement (TKR). Cohort of patients treated by UKR has been studied for satisfaction and pain as endpoints and related to TKR. Materials: At the Centro di Chirurgia Protesica, Istituto Ortopedico ÒGaleazziÒ, Milano (I), more than 600 hip and knee replacements are performed per year. Among these, from February to April 2001, 109 patients have been treated for primary unilateral arthritis of the knee by the same surgeon, same OR team, and environmental conditions. 53 patients received unicompartmental knee replacement (Allegretto TM, Centerpulse) because of unicompartmental knee degeneration. 56 patients received total knee replacement (Innex TM, Centerpulse) for tri-compartmental arthritis. Patients have been preoperative evaluated for age, ASA score, KSS and Function. Postoperative recovery and physio funtions. At 18 months follow-up, cohort of UKR has been evaluated for satisfaction and pain as endpoints by telephone interview. The same has been for TKR group. Results: No differences were between the UKR and TKR cohorts for age at surgery (UKR: 68yrs, 86-45; TKR: 69yrs, 83-51); ASA score, KKS (UKR: 54,2pts, 76-25; TKR: 43,3pts, 75-10); function (UKR: 67,5pts, 95-20; TKR: 60,6pts, 95-10). No differences were for recovery period and rehabilitation program. Within the TKR group had 1 died for post op cardiopulmonary complication. At follow-up patients was judged by the author not eligible for any revision, on clinical and radiological examination. None was lost at follow-up, none revised. At 18 months follow-up, UKR cohort, 52 on 53 patients were satisþed by their knee, event rate 98% (89–100). 18 on 52 were in mild pain and drug use, event rate 34% (28–39), 4 of those in trouble with stairs. 1 patient was not satisþed. For TKR cohort, 49 on 55 patients were satisþed, event rate 89% (81–97). 24 on 49 reported pain and drug use, event rate 49% (42–56), 7 of those in stairs climb limits. 6 patients were not satisþed. Conclusion: Because of long time is needed to produce adequate number in joint replacement groups, statistical method relies on survivorship analysis for studying adverse events. However confounding factors, lost of follow-up, and revision as endpoint may mislead results (Murray DW. et al. JBJS 1993). Meanwhile, randomised clinical trial provides a cornerstone not only for evidence-based medicine but also for evidence public health, evidence based hospital administration, evidence based purchasing, and evidence based consumerism (Sackett DL et al. BMJ 1994).

Our TKR cohort pain endpoint survival rate is comparable with others in literature (Murray DW, Frost SJD. JBJS 1998). Comparing TKR with UKR groups has limitation and EBM is not eligible for such groups. However, cohort study for joint replacement, performed within a short period of time, and less confounding factors, increases assessment reliability and endpoints deþ nition. Overall, our result shows lower pain and higher satisfaction events rate for UKR than TKR.

A good primary mechanical stability is a prerequisite for secondary cementless stem fixation by osseointegration. The construction, basic shapes and their development, as well as the nature of the surface in the CLS system are thus directed towards this goal.

The biomechanical concept of the CLS stem is characterised by the three-dimensional V-form, the strongly accentuated ribs in the proximal region and the all-round conical form of the distal part of the stem. The construction uses the adaptable trabeculum for the primary fixation. The features that characterise the CLS stem are found both in the classical version and the varus version.

The fixation of the stem in the proximal area should guarantee that transmission of force is retained within this area. The interposition of the cancellous structures reduces the danger of the bond between the bone and prosthesis becoming stiff. On introduction, the axial ribs exercise a cutting action and promote stability. In order to avoid tension peaks, the surfaces of the distal part of the stem are well rounded. The shape of the distal part of the stem is kept relatively slender, thus direct contact with the cortex is avoided. This means reduced incidence of pain for the patient, plus the new trabecular structures can form between the cortex and the implant, which eventually result in osseointegration.

To what extent and how quickly an implant becomes integrated is not just a question of primary stability. Important factors that have an influence also include the material and the surface structures of the prosthesis. It is generally the case that new bone grows preferentially on protruding parts such as prosthesis ribs or edges, and also on existing trabeculae, such as those altered by the surgery. The formation of new bone tissue in association with the CLS prosthesis was thoroughly investigated in many histological studies. The coarse-grained titanium alloy is, to a great extent, osteophilic. This is demonstrated by the fact that bone marrow or new bone can form directly on the surface of the CLS prosthesis.

The indications can be calculated on the basis of four key parameters: age, sex, the degree of osteoporosis, and the morphology of the femur. The morphological-cortical index (MCI) is used as an instrument to determine the shape of the femur. This provides a reliable method of classification of one of three basic morphological types: trumpet-shaped, cylindrical, and dysplastic.

The first 300 consecutive primary total hip arthroplasty (THA) procedures (299 patients), from Dec. 1983 to Apr. 1985, using a collarless, three-dimensional tapered, straight, titanium alloy stem with a grit-blasted surface, were evaluated clinically and radiographically in up to 16 years of follow-up. Radiographic evaluation assessed Engh’s implant-bone femoral fixation score, implant-bone demarcation, and periprosthesis osteolysis. The average duration of long-term radiographic follow- up was 12.6 years (10–16 years).

Patients were evaluated clinically by the HHS system. At last examination, five hips were lost to follow-up and 69 patients had died. The femoral revision rate was 7% (two aseptic loosening, five septic, 12 osteolysis). Femoral component survivorship was 95% at 10 years and 90% at 14 years. Femoral implant-bone fixation was stable, bone ingrowth in 97% stable, fibrous fixation in 1% and unstable, fibrous-fixation in 2% of the cases revised for acetabular mobilisation.

The grit-blasted, press-fit, collarless, tapered femoral component continued to perform well. While considering a “first-generation” cementless stem, CLS is still in use without virtually any design modifications.

Mini-invasive technique relies on mini skin incision: 5–8 cm long, no tourniquet, no Hoffa’s fat pad, and patellar tendon stress. The incision has to allow the inspection in flexion of the contralateral compartments and the inspection–treatment of the patella in extension (osteophyte removal). During the procedure it is mandatory to check the proper position of the prosthesis components. In case of varus or valgus degeneration, we can perform a parapatellar medial or lateral minimally invasive approach.

In my own experience, from 1984 to 1996, I performed 1067 unicondylar knee replacements (UKR) by the traditional approach. From 1997 to 2001, I operated using the mini-invasive technique on 1091 UKRs. The comparison between these two groups of patients has shown less postoperative pain, quicker recovery and shorter hospitalisation time in the mini-invasive group. There were no differences between groups for shortterm results. For long-term results, in March 2001 we evaluated 112 patients with a UKR (AllegrettoTM – Sulzer Medica) and a relative standard approach with 8–10 years follow-up.

These implants were performed between November 1990 and March 1993, in 105 cases in the medial compartment and in seven cases in the lateral. The preoperative indications were: 98 arthritis, four HTO sequelae, four condyle osteonecrosis, three post-traumatic sequelae, three UKR revision, in eight cases the ACL had degenerated. At follow-up, seven patients were dead, 0 were lost, three revised and two submitted to an arthroscopy (lateral meniscus degeneration). The cause of three revisions (2.5%) was one femoro-patellar degeneration and two aseptic loosening, no septic revision. We think that these survival rates cannot be modified by a minimally invasive technique.

Technically, the mini skin incision needs the observance of some basic rules. A preoperative plan is mandatory to address the thickness and slope of bone cuts as well as prosthesis size. Prosthesis instruments and hardware must be designed to be suitable for minimal bone exposure. With experience we can utilise free hand surgical technique; this technique reduces the operative time and invasiveness. Skin landmarks have to be easily recognised on the anatomical region to preserve the soft tissue around the approach. Skin incision is para-patellar medial or lateral. It starts proximally 1 cm below the superior margin of the patella. It ends distally within 1 cm below the joint line. To expose the femoral condyle it is not necessary to dislocate the patella, but it should be relatively subluxed. When the prosthesis is fitted, the mini-incision allows for a reliable check of stability, alignment, and prosthesis component relation.

The mini-invasive technique permits faster surgery and is particularly suitable for one-stage bilateral UKR procedures and patients with systemic heart and vascular disease. Concerns may arise: the learning curve. The mini para-patella skin incision, among the superior and inferior geniculata arteries, allows a safe and straight approach to the knee.