Purpose: To compare the site of lesions in medial and lateral unicompartmental osteoarthritis (OA) of the knee.

Methods: Patients with medial (n=35) and lateral (n=15) OA, having unicompartmental knee arthroplasty, were recruited. Intra-operatively, the distance between the anterior, posterior, medial and lateral margins of the full-thickness lesion and reference lines dividing the condyles was measured. The midpoints of lesions were calculated and groups were compared. Lateral radiographs were used to determine the relationship between the lesion site and knee flexion angle (KFA).

Results: Femoral lesion: In lateral OA, the midpoint of lesions was 25.0mm (SD:8.8) posterior to the reference line passing transversely through the apex of the inter-condylar notch. This was significantly different (p< 0.001) from midpoint in medial OA, which was 10.7mm (SD:9.4) posterior to the reference line.

Tibial lesion: In lateral OA, the midpoint of lesions was 2.0mm (SD:6.5) posterior to the reference line passing through the mid-coronal plane of the resected tibia. This was located significantly more posterior (p=0.038) than midpoint in medial OA, which was 2.2mm (SD:5.7) anterior to the reference line.

Knee Flexion Angle: In lateral OA, the midpoint of lesions was on average at 40° flexion and sites of smaller lesions were very variable. The lesion expanded both anteriorly and posteriorly. In medial OA, smaller femoral lesions occurred in full extension and extended further posteriorly with disease progression.

No significant difference was demonstrated in medial and lateral localisation of the lesions.

Conclusion: Medial OA begins near full extension, progresses in a predictable manner and is perhaps initiated by events occurring at heel strike. Lateral OA begins in flexion in a less predictable manner, at KFA above that seen during the gait cycle. The different sites of lesions in medial and lateral OA suggest different aetiology and pathophysiology. Therefore, prevention and treatment strategies should be different.

Aim: To measure contact pressures in vivo in patients with unicompartmental arthritis fitted with osteoarthrosis (OA) braces to see if the arthritic side of the joint is unloaded.

Method: A thin flexible sensor (TekScan) was manoeuvered arthroscopically into the medial compartment of the knee joint under local anaesthesia in patients with unicompartmental OA of the knee undergoing either therapeutic or diagnostic arthroscopy. All 15 patients had been fitted with a brace before the arthroscopy. Measurements were made within the compartment of double leg stance and single leg stance. Ground reaction force using a load cell was measured for 14 patients and the knee sensor data were normalised relative to this. Recordings were then repeated with the patients with different commercially available braces.

Results: The first two groups of patients showed significant reductions in pressures. Normalised knee sensor forces were reduced to 68%(Sd 22%) and 61%(Sd31%). In the last group of patients, reductions in pressure recordings were less between no-brace and brace. Three patients produced low signals suggesting incorrect sensor replacement.

Conclusions:

Significant unloading of the osteoarthritic compartment could be observed by applying manually a valgus force to the knee.

Background. Medial open wedge high tibial osteotomy (MOWHTO) has been accepted as a highly effective option for the treatment of medial unicompartmental osteoarthritis of the knee. Although pain in the medial joint line is significantly relieved after MOWHTO, some patients complain of pain over pes anserinus after the osteotomy, necessitating implant removal for pain relief. Purpose. The purpose of this study is to define the implant removal rate after MOWHTO due to patient complaints. Methods. 103 knees of 72 patients who underwent MOWHTO for medial unicompartmental osteoarthritis between 2010 and 2018 with a follow-up of at least 24 months were enrolled in the study. Patients were evaluated with the Knee Injury and Osteoarthritis Outcome Score (KOOS), Oxford Knee Score (OKS) and Visual Analogue Score (VAS) for pain in the medial knee joint (VAS-MJ). All tests were performed before the surgery, at 12 months after surgery. VAS value for pain over pes anserinus (VAS-PA) was recorded at 12 months after MOWHTO and at 3 months after implant removal. Results. Mean follow-up was 31±5.4 months. TomoFix® medial high tibia plate (DePuy Synthes, Raynham, MA, USA) was used for the fixation of osteotomy in all cases. Significant improvement in KOOS, OKS and VAS-MJ were observed 12 months after MOWHTO. Average values of VAS-MJ and VAS-PA were 21.7±7.1 and 34±8.4, respectively. Implant removal was needed for 65 (63.1%) knees. There were no significant differences in regard of postoperative KOOS (p=0.134), OKS (p=0.287) and VAS-MJ (p=0.416) scores between patients for which implant removal was needed or not. VAS-PA value decreased significantly at 3 months after implant removal (p<0.001). Conclusion. A large portion of patients needed implant removal after MOWHTO to relieve pain over pes anserinus even if knee function was significantly improved. Lower profile plates may be preferred to avoid secondary implant removal surgery after MOWHTO

High Tibial Osteotomy (HTO) is an established treatment for unicompartmental osteoarthritis of the knee with malalignment. The classic procedure for correcting varus deformity is the lateral closed wedge osteotomy of the tibia with osteotomy of the fibula. The disadvantages of this technique are well known. Open wedge osteotomy from the medial sideeliminates the risk of compartment syndrome and peroneal nerve injuries. A new fixation device (TomoFix(tm)) with an adapted surgical technique allows stable fixation of the osteotomy without the need to fill the osteotomy gap with bone grafts. In a prospective study, 92 consecutive cases were treated with this procedure. Bony healing with remodelling of the medial and posterior cortical bone was observed. Full weight-bearing was possible ten weeks after surgery. There were no implant failures. Complications included one delayed union, two revarisations and one deep infection. Keywords: High Tibial Osteotomy (HTO), openwedge osteotomy, TomoFix(tm) plate, medial osteoarthritis, varus knee

Introduction. Over the past several decades, numerous surgical procedures have been perfected in the inpatient hospital setting and then evolved into outpatient procedures. This has been shown to be a safe and economical transition for many orthopedic procedures. A prime example is ACL reconstruction. We report here our early experience with our initial consecutive series of outpatient UKA's done in a free standing ASC (ambulatory surgery center). Materials and Methods. From 8/26/2008 to 5/20/12 there were 60 UKA's performed as outpatient procedures at a free standing ASC. Average patient age was 57.7 years (range of 46–69). Medical comorbidities included 22 patients with HTN and 7 with diabetes. All patients had general anesthesia with periarticular injection of the involved knee (25 cc's of Marcaine with epinephrine 1:100,000) and an intraarticular injection after closure of the capsule with 25 cc of Marcaine with epinephrine mixed with 5 cc of morphine sulfate. Patients without allergy to sulfa were given 200mg of Celebrex bid for three days and hydrocodone/acetaminophin 10/325 1–2 tabs q4 hours prn pain. Patients were discharged home when stable, ambulating with aids as needed, with length of stay ranging from 60–180 minutes (average of 85 minutes). Results. No patients required admission to the hospital for any reason. There was one hemarthrosis in a medial UKA which developed on postoperative day 4. There was uneventful resolution of this event with conservative management and an excellent result was achieved. The vast majority of patients were ambulating well and without walking aids at the 2 week postoperative evaluation. The total number of UKAs performed by the author in the ASC since 8/26/2008 is now 282, still without any complications requiring admission to the hospital. Conclusion. Outpatient UKA performed in an ambulatory surgery center was found to be a safe, efficient, and effective method for the management of unicompartmental osteoarthritis of the knee in this relatively healthy cohort of patients. It is now our routine approach for patients undergoing UKA, with inpatient hospitalization being reserved for those patients who are at higher postoperative risk due to multiple medical comorbidities

Introduction: High tibial osteotomy is an established procedure for the mid-term treatment of unicompartmental osteoarthritis of the knee, especially in young patients. Nevertheless, its performance at the proximal end of the tibia, close to the site of insertion of the extensor mechanism of the knee, might produce anatomic alterations of the latter, which, in turn, could influence the final result. Aim: The purpose of the present retrospective study is the radiologic evaluation of the anatomic changes of the extensor mechanism of the knee, caused by high tibial valgus osteotomy (closed-wedge step osteotomy, with internal fixation). Material – Method: For this purpose we studied the X-rays of 44 kness (pre-op, p-op and 1 year p-op) that had undergone the above procedure. The assessed variables were the horizontal and vertical shift of tibial tubercle as well as the position of the patella (patellar vertical height, Linclau, Caton). Results: We didn’t find any statistically significant difference of the postoperative position of the patella with respect to the preoperative one (p=0.88), whereas there was definite proximal and anterior shift of the tibial tubercle in a statistically significant degree (p< 0.01) with respect to the preoperative situation. Conclusions: The certain type of high tibial osteotomy seems to impart an unloading effect on the patellofemoral joint (due to the anterior shift of the tibial tubercle). On the contrary, the vertical shift of the tibial tubercle seems to have no effect to the postoperative position of the patella

Introduction: High tibial osteotomy is an established procedure for the mid-term treatment of unicompartmental osteoarthritis of the knee. Nevertheless, it produces anatomic alterations of the proximal part of tibia, which might affect the later performance of TKR. These anatomic changes are basically patella infera and medialization of the tibial medullary canal with respect to the tibial plateau (tibial condilar offset). Material and Method: The purpose of the present retrospective study is the evaluation of the above mentioned anatomic changes, caused by high tibial valgus osteotomy (Mittelmeier’s technique). For this purpose we studied the X-rays of 44 kness (pre-op, p-op and 1 year p-op) that had under gone the above procedure. Results: We didn’t find any statistically significant difference of the postoperative position of the patella with respect to the preoperative one, whereas there was definite medialization of the tibial anatomic axis with respect to the preoperative situation. The latter change was directly correlated with the degree of valgus correction. The mean change of the tibial anatomic axis (as estimated by the value of the tibial condylar offset ratio) was 15%. Conclusions: Although Mittelmeier’s high tibial valgus osteotomy does not cause any significant alteration of the position of the patella, it does alter the relationship of the tibial medullary canal with respect to the tibial plateau in direct correlation with the degree of valgus correction. Thus, the performance of TKR after proximal tibial osteotomy necessitates a thorough preoperative plan and the selection of the appropriate implant

Introduction: The aim of this study was to determine the outcome of Tomofix plate fixation, in joint retaining surgery, for Medial compartment Osteoarthritis of the knee in young patients. Methods: We report on 33 patients (36 knees) who underwent High tibial osteotomy for unicompartmental osteoarthritis of the knee. The mean age was 39.5 (30–49). There were 20 males and 13 female. All the patients had Medial opening-wedge type Osteotomy using the Tomofix device. The mean duration of follow-up was 48 months (44–60 months). The patients were assessed on the basis of pre and post-operative oxford knee score, knee range of motion, radiological evidence of healing of the osteotomy site and alignment of the knee. Results: There were no nonunions at the osteotomy site and the medial open-wedge filled-in without any need for bone graft or its substitutes. The mean preoperative oxford knee score was 48 (S.D 4.7 Range 38–54). This improved to a mean score of 22 (S.D 5.9 Range 17–31) after 1 year follow-up. The improvement was significant (pvalue= 0.07). The preoperative average knee flexion was 103.1 (S.D 25.2 Range 10–125) which improved after 1 year follow up to 112 (S.D 15.9 Range 0–140). The mean preoperative Femorotibial angle was 10 degrees varus (range 9–15). The mean postoperative Femorotibial angle was 8 deg valgus (range 6–12). Radiologically, there was no loss of correction during our follow-up. One patient had post-operative DVT. Conclusion: Our study shows that Tomofix plate fixation in High Tibial osteotomy gives immediate stability, good deformity correction and allows early rehabilitation. The osteotomy gap does not require bone grafting and the correction is maintained. The Short term functional results are encouraging. Longer-term follow-up is however needed to establish its effectiveness in deferring joint replacement surgery in young patients

Purpose of the study: The aim of this study was to report outcome after more than six years follow-up of a series of 122 unicompartmental prostheses. Material and methods: Cemented HLS® unicompart-mental surface-coated prostheses were implanted in 111 patients (122 knees, 88% medial and 12% lateral) between January 1995 and November 1997 by the same surgeon. These knees presented unicompartmen-tal osteoarthritis (91%) or unicondylar necrosis (9%). An independent senior surgeon reviewed 94 prostheses. Seventeen patients died and ten institutionalized patients free of complaints about their knee could not be fully assessed. Only three patients (2.7%) were lost to follow-up). Clinical data were assessed with the IKS criteria. A complete radiological work-up was available to compare preoperative images with the last follow-up results. Mean follow-up was 88 months (range 72–108 months). Results: After the implantation, 96% of patients were satisfied or very satisfied; 84% had no or little pain. Mean flexion was 133° (range 90–150°). The mean knee score at follow-up was 86/100 (40/100 preoperatively), mean function score 77/100 (61/100 preoperatively). Mean residual misalignment was 6° (7° varus for medial prostheses and 4° valgus for lateral prostheses). Tibial or femoral lucent lines were observed for 22% of the prostheses but with no change and no clinical expression. There was one case of tibial polyethylene wear (1mm). There were eight failures (all before 24 months) with revision with a total knee arthroplasty (two infections, one overlarge component, two tibial loosenings, 3 unexplained pain). The Kaplan-Meier survival at maximum follow-up of 108 months was 93.67%. Discussion: The prostheses implanted in this series were correct indications according to the preceding symposiums. We analyzed the clinical and radiological outcome (overall axial correction, tibial and femoral correction), failures, and reasons for incomplete results. Conclusion: Outcome at more than six years in this series of resurfaced knee prostheses with a polyethylene plateau was good, supporting the correct choice of implant and technique. These results also enabled validation of the principle that unicompartmental arthroplasty is a valid alternative for the treatment of unicompartmental osteoarthritis of the knee joint. Analysis of the failures and the incomplete results discloses interesting avenues for optimizing the surgical technique and improving future clinical and radiological results