Objective. To analyze the short-term outcome after medial open-wedge high tibial osteotomy with a 3D-printing technology in early medial keen osteoarthritis and varus malalignment. Design and Method. 32 knees(28 cases) of mOWHTO (fixation with an angular-stable TomoFix implant(Synthes)) with a 3D-printing technology combined with arhtroscopy were prospectively surveyed with regard to functional outcome(Hospital for special knee score [HSS] score). Pre- and postoperative tibial bone varus angle (TBVA), mechanical medial proximal tibial angle (MPTA), and alignment were analyzed with regard to the result. Results. 32 knees were included (28 patients; mean age 46.5±9.3 years). The follow-up rate was 100% at 1.7±0.6 years (range, 1.2–3.2 years). Pre- and postoperative mechanical tibiofemoral axis were 6.8°±2°of varus and 1.2°± 3.4° of valgus, respectively. HSS score significantly improved from 46.0±18.3 preoperatively to 84±12 at one, 80±7 at two years (P<0.01). Conclusions. Medial open-wedge high tibial osteotomy with a 3D-printing technology combined with arthroscopy in medial keen osteoarthritis and varus malalignment is an accurate and good treatment option. High preoperative TBVA and appropriate corrected angle(0–3° of valgus)) was associated with better functional outcome at final follow-up

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 a joint preserving alternative to knee replacement for medial tibiofemoral osteoarthritis in younger, more active patients. The procedure is technically challenging and limited also by ‘one size fits all’ plates which can result in patient discomfort necessitating plate removal. This clinical trial evaluated A novel custom-made HTO system – TOKA (3D Metal Printing LTD, Bath, UK) for accuracy of osteotomy correction and improvements in clinical outcome scores. The investigation was a single-arm single-centre prospective clinical trial (IRCCS Istituto Ortopedico Rizzoli; ClinicalTrials.gov NCT04574570), with recruitment of 25 patients (19M/6F; average age: 54.4 years; average BMI: 26.8), all of whom received the TOKA HTO 3D planning and surgery. All patients were predominantly diagnosed with isolated medial knee osteoarthritis and with a varus deformity under 20°. Patients were CT scanned pre- and post-operatively for 3D virtual planning and correctional assessment. All surgeries were performed by the lead clinical investigator – a consultant knee surgeon with a specialist interest in and clinical experience of HTO. On average, Knee Society Scores (KSS) improved significantly (p<0.001) by 27.6, 31.2 and 37.2 percentage points respectively by 3-, 6- and 12-months post-surgery respectively. Other measures assessed during the study (KOOS, EQ5D) produced similar increases. Our early experience using custom implants is extremely promising. We believe the reduced profile of the plate, as well as the reduced invasiveness and ease of surgery contributed to faster patient recovery, and improved outcome scores compared to conventional techniques. These clinical outcome results compare very favourably other case-series with published KOOS scores using different devices

Background. Since 2011, the knee service at the Nuffield Orthopaedic Centre has been offering a neutralising medial opening wedge high tibial osteotomy (HTO) to a group of patients presenting with early medial osteoarthritis of the knee, varus alignment and symptoms for more than 2 years. During development of this practice an association was observed between this phenotype of osteoarthritis and the presence of CAM deformity at the hip. Methods. A retrospective cohort study. All patients who underwent HTO since 2011 were identified (n=30). Comparator groups were used in order to establish whether meaningful observations were being made: Control group: The spouses of a high-risk osteoarthritis cohort recruited for a different study at our unit (n=20) Pre-arthroplasty group: Patients who have undergone uni-compartmental arthroplasty (UKA) for antero-medial osteoarthritis (n=20)All patients had standing bilateral full-length radiographs available for analysis using in house developed Matlab-based software for hip measurements and MediCAD for lower limb alignment measurements. Results. A total of 140 limbs from 70 gender-matched subjects were studied. The HTO group had a significantly higher prevalence of CAM lesions defined by an Alpha angle >650. They also had a significantly greater mean alpha angle than both the pre-arthroplasty and control groups [HTO (Avg. 68.3 (±16.1)) vs Pre-arthroplasty (Avg. 59.5 (±15.5)) P=0.01; HTO vs Control (Avg. 58.2 (±13.9)) P=0.007]. Conclusions. The results of this study confirm that our HTO group have a significantly greater prevalence of CAM lesions. A feature not seen in either pre-arthroplasty or control subjects. This group demonstrate independent predictors for progression of OA in both the hip and the knee. To our knowledge this is a novel observation. Level of evidence. Observational cohort study (III)

UKA with mobile bearing is a one of the treatment of medial osteoarthritis. However, some reports refer to the risk of dislocation of the mobile bearing. Past reports pointed out that medial gap might be enlarged in deep flexion position (over 120 degrees), and says that it will lead to instability of the mobile bearing. The purpose of this study is to research the risk factors of enlargement of medial gap in deep flexion position. We performed 81 UKAs with mobile bearing system from November 2013 to December 2015, and could evaluate 41 knees. This study of 41 knees included 9 males and 32 females, with average operation age of 75.4years(63–89years). The diagnosis was osteoarthritis in 39 knees and osteonecrosis in 2 knees. The UKA(Oxford partial knee microplasty, Biomet, Warsaw, IN) was used in all cases. We performed distal femur and proximal tibia osteotomy using CT-Free navigation system(Stryker Navigation System II/precision Knee Navigation ver4.0). And we inserted femoral and tibial trial component, then we placed an UKA tensioner on the medial component of the knee. Using tensioner under 30 lbs, we measured joint medial gap at 0,20,45,90,130(deep flexion) degrees. When we compared medial gap at 90 degrees position with at 130 degrees, we defined it as ‘instability group’ if there was gap enlargement more than 1mm, and defined it as ‘stability group’ if there wasn't. We compared this two groups with regard to age, BMI, femoro-tibial angle (FTA), the diameter of anterior cruciate ligament (ACL), tibial angle and tibial posterior slope angle of the implant. We evaluated preoperative and postoperative FTA by weightbearing long leg antero-posterior alignment view X-rays. We measured ACL diameter at its condyle level in coronal view of MRI. Also we evaluated tibial component implantation angle by postoperative CT using 3D template system. These measurement were analyzed statistically using t test. The stability group contained 26 knees, and the instability group contained 15 knees. Compared with the stability group, the instability group indicated higher FTA (p=0.001). Between 20 and 90 degrees flexion position, there was no change of medial gap. Dislocation of the mobile bearing is one of the complications of UKA and it will need re-operation. It is said to be caused by impingement of the bearing and osteophyte of femur. However, some reports said that dislocation was happened when the knee was flexed deeply or twisted, and there was no impingement. We think it may means that dislocation could be caused by medial gap enlargement. This study indicates that higher FTA could be risk factor of dislocation of mobile bearing. It is important to evaluate preoperatively FTA by X-ray

Great interest in unicompartmental knee arthroplasty (UKA) for medial osteoarthritis has rapidly increased following the introduction of minimally invasive UKA (MI-UKA). This approach preserves the normal anatomy of knee, causes less damage to extensor mechanism and results in a more rapid post-operative recovery. However, experience with this approach is limited in China. The aim of this report was to determine the short-term clinical and radiographic outcomes of MI-UKA in the Chinese, and to identify any features that are unique to this population. Fifty two knees, in forty-eight patients, with medial compartmental osteoarthritis treated by MI-UKA via C-arm intensifier guide (CAIG) from May 2005 to January 2009 were reviewed. Pain and range of motion (ROM) was assessed using the HSS scoring system before and after surgery. Pre- and postoperative alignment of the lower limbs was measured and compared. The mean follow up time was 24 months (12-42 months). In all cases the pain over medial compartment of the knees was relieved or subsided. The post-operative ROM was 0-136 degree (mean 122degree), and the mean alignment was 2degree varus (0- 7degree varus). The HSS score increased from 72(61-82) to 92(72-95). 93% of the postoperative scores were good or excellent. Interestingly, the distribution of femoral component sizes of these patients was XS 2%, Small 83%, Medium 15%, Large 0%, XL 0%; whereas tibial component size was AA 27%, A 55%, B 15%, C 3%, D 0%, E 0%, and F 0%. The optimal fitted match between tibial and femoral size was: tibia AA and A with XS and small femur, tibia B and C with medium femur. The estimated match was: tibia D and E with large femur, tibia F with XL femur. In contrast to the Oxford report, the sizes of these components are smaller and not in correlation with the height, weight and BMI of the patients. We conclude that MI-UKA is an effective method for treating medial compartmental osteoarthritis of the knee in the Chinese population. CAIG is a feasibly intraoperative measure to predict femoral component sizes. However, component sizes and combinations are different from the Oxford guideline