Summary. This study shows a significant reduction in knee adduction moment in patients with medial compartment osteoarthritis, in both the symptomatic and asymptomatic knees. Long-term follow-up studies are required to confirm the effect of treating the asymptomatic side on disease progression. Background. The knee is the commonest joint to be affected by osteoarthritis, with the medial compartment commonly affected. Knee osteoarthritis is commonly bilateral, yet symptoms may initially present unilaterally. Higher knee adduction moment has been associated with the development and progression of medial compartment knee osteoarthritis. The aim of this study was to assess the effect of lateral wedge insoles on the asymptomatic knee of patients with unilateral symptoms of medial compartment knee osteoarthritis. Methods. Twenty patients were assessed using a 3D optoelectronic tracking system, with 16 infrared camera, passive markers and four force platforms. Three different insoles were tested; a standard control shoe, the Boston lateral wedge insole (inclined at 5° throughout the full length of the insole) and the Salford insole (inclined at 5° throughout the full length of the insole, with medial arch support). A minimum of 5 trials per each insole were used. Kinetic and kinematic data were collected and processed using Qualysis Track Manager ® and Visual 3D™. Results. There was a significant reduction in knee adduction moment for both the Salford and Boston insoles as compared to the control shoe. This was 9.5–14.2% for the asymptomatic side, and 5.8–10.7% for the symptomatic side for the Salford and Boston insoles respectively. Although the reduction was larger on the asymptomatic side, this was not statistically significant. Patients reported significant reduction in pain with both Salford and Boston insoles as compared to the control shoe, and found the Salford insole to be the most comfortable. Stride length and walking speed was significantly higher with the Salford insole. Conclusions. This study confirms the effect of lateral wedge insoles on reducing knee adduction moment in patients with medial compartment osteoarthritis, in both the symptomatic and asymptomatic knees. Long-term follow-up studies are required to confirm the effect of treating the asymptomatic side on disease progression

The medial opening-wedge high tibial osteotomy (OW-HTO) is an accepted option to treat the isolated medial compartment osteoarthritis (OA) in varus knee. Despite satisfactory outcomes were described in literature, consistent complication rate has been reported and the provided accuracy of coronal alignment correction using conventional HTO techniques falls short. Patient specific instrumentations has been introduced with the aim to reduce complications and to improve the intra-operative accuracy according to the pre-operative plan, which is responsible for the clinical result of the surgery. In this talk, an overview of the clinical results of HTO patient specific instrumentation available in literature will be performed. Moreover, preliminary intra-operative and clinical results of a new customised 3-D printed cutting guide and fixation plate for OW-HTO will be presented

Summary Statement. This project proves that Patellofemoral (PF) joint degeneration is not a contraindication to medial unicompartmental knee replacement. Introduction. Unicompartmental knee arthroplasty (UKA) is a recognised procedure for treatment of medial compartment osteoarthritis. Patellofemoral (PF) joint degeneration is widely considered to be a contraindication to medial unicompartmental knee replacement. We examined the validity of this preconception using information gathered prospectively on consecutive patients who underwent UKA using the Repicci II® UKA prosthesis for medial compartment osteoarthritis. Methods. We prospectively collected data on 147 consecutive patients who underwent the Repicci II® UKA for medial compartment osteoarthritis. All operations were performed between July 1999 and September 2000 by the same surgeon. The status of the PF joint was assessed intra-operatively in all patients, and accordingly patients were divided into two groups, one group with a normal PF joint, and the second group with degenerative changes of the PF joint. Variables measured for outcome included the International Knee Society (IKS) score, limb alignment, and range of motion. Radiographs were assessed for progression of disease or failure of implant. The mean follow-up was 9.4 years (range: 5–10.7 years). Patients were reviewed initially at 2 weeks, and then at 6 months post-operatively. They were subsequently reviewed on an annual basis.. All patients completed an IKS score preoperatively and at last follow-up. Age, gender, BMI, length of hospital stay, perioperative complications, all subsequent surgery, including revision of the prosthesis, and survivorship at 10 years was recorded, and results of the 2 groups compared. Results. A total of 147 patients were included in the study. None were lost to follow-up. Sixty nine had associated PF osteoarthritis (group A) while 78 patients had a normal PF compartment when assessed intra-operatively (group B). Post-operative outcomes of the two groups were compared using the ANCOVA analysis with adjustment for pre-operation values firstly, and adjusting also for gender, age, BMI and follow-up secondly. There were no significant differences in terms of IKS, alignment, and flexion between the two groups. However, patients in group B had significantly better extension post-operatively than patients in group A (p<0.05). Conclusion. We concluded that damage to the articular cartilage of the patellofemoral joint to the extent of full-thickness cartilage loss is not a contraindication to the Repicci II® unicondylar knee arthroplasty for medial compartment osteoarthritis. However, extension is significantly improved post-operatively in those patients with minimal or no PF joint degenerative disease

Abstract. OBJECTIVES. Valgus high tibial osteotomy (HTO) represents an effective treatment for patients with medial compartment osteoarthritis (OA) in a varus knee. However, the mechanisms which cause this clinical improvement are unclear. Previous studies suggest a wider stance gait can reduce medial compartment loading via reduction in the external knee adduction moment (KAM); a measure implicated in progression of medial compartment OA. This study aimed to measure whether valgus HTO is associated with a postoperative increase in static stance width. METHODS. 32 patients, recruited in the Biomechanics and Bioengineering Centre Versus Arthritis HTO study, underwent valgus (medial opening wedge) HTO. Weightbearing pre- and post- operative radiographs were taken showing both lower limbs. The horizontal distance, measured from a fixed point on the right talus to the corresponding point on the left, was divided by the talus width to give a standardised “stance width” for each radiograph. The difference between pre- and post- operative stance width was compared for each patient using a paired sample t-test. RESULTS. Preoperatively, mean stance was 4.00 talar-widths but postoperatively this increased to 5.41. This mean increase of 1.42 talar-widths was statistically significant (p=0.001) and represents a mean proportional increase in stance width of 35.5% following HTO. Of the 32 patients, 23 showed increased stance width and 9 decreased (range −4.64 to 6.00 talar-widths). CONCLUSIONS. These findings indicate an association of frontal plane surgical realignment at the proximal tibia via a medial opening wedge HTO with an increased stance width on postoperative radiographs. Considering both wider stance gait and HTO have been shown to affect the progression of medial compartment OA, these results may explain one mechanism contributing to the efficacy of HTO surgery. However, the range of changes in stance width suggests significant variability in how patients adapt at a whole-limb and whole-body level following HTO. Declaration of Interest. (b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project

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

Objectives. This study reports on a secondary exploratory analysis of the early clinical outcomes of a randomised clinical trial comparing robotic arm-assisted unicompartmental knee arthroplasty (UKA) for medial compartment osteoarthritis of the knee with manual UKA performed using traditional surgical jigs. This follows reporting of the primary outcomes of implant accuracy and gait analysis that showed significant advantages in the robotic arm-assisted group. Methods. A total of 139 patients were recruited from a single centre. Patients were randomised to receive either a manual UKA implanted with the aid of traditional surgical jigs, or a UKA implanted with the aid of a tactile guided robotic arm-assisted system. Outcome measures included the American Knee Society Score (AKSS), Oxford Knee Score (OKS), Forgotten Joint Score, Hospital Anxiety Depression Scale, University of California at Los Angeles (UCLA) activity scale, Short Form-12, Pain Catastrophising Scale, somatic disease (Primary Care Evaluation of Mental Disorders Score), Pain visual analogue scale, analgesic use, patient satisfaction, complications relating to surgery, 90-day pain diaries and the requirement for revision surgery. Results. From the first post-operative day through to week 8 post-operatively, the median pain scores for the robotic arm-assisted group were 55.4% lower than those observed in the manual surgery group (p = 0.040). At three months post-operatively, the robotic arm-assisted group had better AKSS (robotic median 164, interquartile range (IQR) 131 to 178, manual median 143, IQR 132 to 166), although no difference was noted with the OKS. At one year post-operatively, the observed differences with the AKSS had narrowed from a median of 21 points to a median of seven points (p = 0.106) (robotic median 171, IQR 153 to 179; manual median 164, IQR 144 to 182). No difference was observed with the OKS, and almost half of each group reached the ceiling limit of the score (OKS > 43). A greater proportion of patients receiving robotic arm-assisted surgery improved their UCLA activity score. Binary logistic regression modelling for dichotomised outcome scores predicted the key factors associated with achieving excellent outcome on the AKSS: a pre-operative activity level > 5 on the UCLA activity score and use of robotic-arm surgery. For the same regression modelling, factors associated with a poor outcome were manual surgery and pre-operative depression. Conclusion. Robotic arm-assisted surgery results in improved early pain scores and early function scores in some patient-reported outcomes measures, but no difference was observed at one year post-operatively. Although improved results favoured the robotic arm-assisted group in active patients (i.e. UCLA ⩾ 5), these do not withstand adjustment for multiple comparisons. Cite this article: M. J. G. Blyth, I. Anthony, P. Rowe, M. S. Banger, A. MacLean, B. Jones. Robotic arm-assisted versus conventional unicompartmental knee arthroplasty: Exploratory secondary analysis of a randomised controlled trial. Bone Joint Res 2017;6:631–639. DOI: 10.1302/2046-3758.611.BJR-2017-0060.R1