Aims. The use of high tibial osteotomy (HTO) to delay total knee arthroplasty (TKA) in young patients with osteoarthritis (OA) and constitutional deformity remains debated. The aim of this study was to compare the long-term outcomes of TKA after HTO compared to TKA without HTO, using the time from the index OA surgery as reference (HTO for the study group, TKA for the control group). Methods. This was a case-control study of consecutive patients receiving a posterior-stabilized TKA for OA between 1996 and 2010 with previous HTO. A total of 73 TKAs after HTO with minimum ten years’ follow-up were included. Cases were matched with a TKA without previous HTO for age at the time of the HTO. All revisions were recorded. Kaplan-Meier survivorship analysis was performed using revision of metal component as the endpoint. The Knee Society Score, range of motion, and patient satisfaction were assessed. Results. Mean follow-up was 13 years (SD 3) after TKA in both groups. The 20-year Kaplan-Meier survival estimate was 98.6% in TKA post-HTO group (HTO as timing reference) and 81.4% in control group (TKA as timing reference) (p = 0.030). There was no significant difference in clinical outcomes, radiological outcomes, and complications at the last follow-up. Conclusion. At the same delay from index surgery (HTO or TKA), a strategy of HTO followed by TKA had superior knee survivorship compared to early TKA at long term in young patients. Level of evidence: III. Cite this article: Bone Jt Open 2023;4(2):62–71

The aim of this study was to determine the long term 20 year survival and outcomes of high tibial osteotomy (HTO). 100 consecutive subjects underwent HTO under the care of a single surgeon between 2000 and 2002, consented to participation in a prospective study and completed preoperative WOMAC scores. Subjects were reviewed at 10 years, and again at a minimum of 20 years after surgery. PROMS included further surgery, WOMAC scores, Oxford Knee Score (OHS), KOOS, and EQ-5D, and satisfaction with surgery. 20 year survival was assessed with Kaplan-Meir analysis, and failure defined as proceeding to subsequent knee arthroplasty. The mean age at HTO was 50 years (range 26-66), and 72% were males. The 5, 10, and 20 year survival of the HTO was 88%, 76%, 43% respectively. On multiple regression analysis HTO failure was associated with poor preoperative WOMAC score of 45 or less (HR 3.2, 95% CI 1.7-6.0, p=0.001), age at surgery of 55 or more (HR 2.3, 95% CI 1.3-4.0, p=0.004), and obesity (HR 1.9, 95% CI 1.1-3.4, p=0.023). In patients who met all criteria of preoperative WOMAC score of 45 or less, age <55 years and body mass index of <30 HTO survival was 100%, 94%, and 59% at 5, 10 and 20 years respectively. Of those who had not proceeded to TKA the mean Oxford Score was 40, KOOS Pain score was 91 and KOOS function score was 97. 97% reported they were satisfied with the surgery and 88% would have the same surgery again under the same circumstances. At 20 years after HTO 43% had not proceeded to knee arthroplasty, and were continuing to demonstrate high subjective scores and satisfaction with surgery. HTO survival was higher in those under 55 years, with BMI <30 and baseline WOMAC score of >45 at 59% HTO survival over 20 years. HTO may be considered a viable procedure to delay premature knee arthroplasty in carefully selected subjects

High tibial osteotomy is an efficient treatment for medial compartment osteoarthritis of the knee; its used for middle aged patients with high activity levels and can delay the need for total arthroplasty. The results of total knee arthroplasty after failed high tibial osteotomy are controversies; several authors reported inferior outcomes, but others have concluded that tibial osteotomy doesn't bias following total arthroplasty. The aim of this study was to evaluate the results of failed high tibial osteotomy subsequently converted to total knee arthroplasty and compare the results to group of patients underwere primary arthroplasty; the authors evaluate some of technical problems that a previous high tibial osteotomy can generate, like scar tissue, patellar tendon shortening and changes of proximal tibial anatomy. Methods. 50 total knee arthroplasty performed after a previous closed wedge osteotomy were matched with 50 patients operated with a primary knee prosthesis for osteoarthritis. The time from a proximal tibial osteotomy to a prosthesis operation was in mean eight years. Results. the Knee Society clinical and radiographic score system and W.O.M.A.C. evaluation were used to evaluate knees before surgery and at each follow up (average 5 years). At an average of five years follow up, the clinical results of total knee arthroplasty after high tibial osteotomy were similar to those of primary knee prosthesis. Discussion. in our study revision of failed proximal tibial osteotomy appears to have more technical difficulties but with overall outcomes that remain comparable at results after primary total knee arthroplasty, so tibial osteotomy is considered a valid option in younger and very active patients with unicompartmental arthritis

High tibial osteotomy is an efficient treatment for medial compartment osteoarthritis of the knee; its used for middle aged patients with high activity levels and can delay the need for total arthroplasty. The results of total knee arthroplasty after failed high tibial osteotomy are controversies; several authors reported inferior outcomes, but others have concluded that tibial osteotomy doesn’t bias following total arthroplasty. The aim of this study was to evaluate the results of failed high tibial osteotomy subsequently converted to total knee arthroplasty and compare the results to group of patients underwere primary arthroplasty; the authors evaluate some of technical problems that a previous high tibial osteotomy can generate, like scar tissue, patellar tendon shortening and changes of proximal tibial anatomy. Methods: 50 total knee arthroplasty performed after a previous closed wedge osteotomy were matched with 50 patients operated with a primary knee prosthesis for osteoarthritis. The time from a proximal tibial osteotomy to a prosthesis operation was in mean eight years. Results: the Knee Society clinical and radiographic score system and W.O.M.A.C. evaluation were used to evaluate knees before surgery and at each follow up (average 5 years). At an average of five years follow up, the clinical results of total knee arthroplasty after high tibial osteotomy were similar to those of primary knee prosthesis. Discussion: in our study revision of failed proximal tibial osteotomy appears to have more technical difficulties but with overall outcomes that remain comparable at results after primary total knee arthroplasty, so tibial osteotomy is considered a valid option in younger and very active patients with unicompartmental arthritis

High tibial osteotomy is an efficient treatment for medial compartment osteoarthritis of the knee; its used for middle aged patients with high activity levels and can delay the need for total arthroplasty. The results of total knee arthroplasty after failed high tibial osteotomy are controversies; several authors reported inferior outcomes, but others have concluded that tibial osteotomy doesn’t bias following total arthroplasty. The aim of this study was to evaluate the results of failed high tibial osteotomy subsequently converted to total knee arthroplasty and compare the results to group of patients underwere primary arthroplasty; the authors evaluate some of technical problems that a previous high tibial osteotomy can generate, like scar tissue, patellar tendon shortening and changes of proximal tibial anatomy. Methods: 50 total knee arthroplasty performed after a previous closed wedge osteotomy were matched with 50 patients operated with a primary knee prosthesis for osteoarthritis. The time from a proximal tibial osteotomy to a prosthesis operation was in mean eight years. Results: the Knee Society clinical and radiographic score system and W.O.M.A.C. evaluation were used to evaluate knees before surgery and at each follow up (average 5 years). At an average of five years follow up, the clinical results of total knee arthroplasty after high tibial osteotomy were similar to those of primary knee prosthesis. Discussion: in our study revision of failed proximal tibial osteotomy appears to have more technical difficulties but with overall outcomes that remain comparable at results after primary total knee arthroplasty, so tibial osteotomy is considered a valid option in younger and very active patients with unicompartmental arthritis

High tibial osteotomy is an efficient treatment for medial compartment osteoarthritis of the knee; its used for middle aged patients with high activity levels and can delay the need for total arthroplasty. The results of total knee arthroplasty after failed high tibial osteotomy are controversies; several authors reported inferior outcomes, but others have concluded that tibial osteotomy doesn’t bias following total arthroplasty. The aim of this study was to evaluate the results of failed high tibial osteotomy subsequently converted to total knee arthroplasty and compare the results to group of patients underwere primary arthroplasty; the authors evaluate some of technical problems that a previous high tibial osteotomy can generate, like scar tissue, patellar tendon shortening and changes of proximal tibial anatomy. Methods: 50 total knee arthroplasty performed after a previous closed wedge osteotomy were matched with 50 patients operated with a primary knee prosthesis for osteoarthritis. The time from a proximal tibial osteotomy to a prosthesis operation was in mean eight years. Results: the Knee Society clinical and radiographic score system and W.O.M.A.C. evaluation were used to evaluate knees before surgery and at each follow up (average 5 years). At an average of five years follow up, the clinical results of total knee arthroplasty after high tibial osteotomy were similar to those of primary knee prosthesis. Discussion: in our study revision of failed proximal tibial osteotomy appears to have more technical difficulties but with overall outcomes that remain comparable at results after primary total knee arthroplasty, so tibial osteotomy is considered a valid option in younger and very active patients with unicompartmental arthritis

Abstract. High tibial osteotomy (HTO) is a well-recognised procedure to address medial compartment osteoarthritis (OA). There remains dispute on the impact of pre-operative patient factors on patient related outcome measures (PROMS). Does BMI and age affect > 2 year and > 5 year oxford knee scores (OKS) and Knee injury and osteoarthritis outcome scores (KOOS). A retrospective review of a prospectively collected database was performed. Timeframe was 26/6/2014 and 25/8/2022. BMI and age were recorded. OKS and KOOS were collected at > 2 years and > 5 years. There were 81 procedures included, of these 50 had OKS and KOOS scores at > 2 years and 35 at > 5 years. Median BMI was 28.5kg/m. 2. , range was 18.6–40.8kg/m. 2. Spearman's rank for >2 year OKS was p(df)=−0.210 p=0.157, > 5 year OKS p(df)=−0.215 p=0.230. For > 2 year and > 5 year KOOS subscales there were no statistically significant associations on Spearman's rank. For age, median age was 52.5, range 26–71 years old. OKS at >2 year p(df)=0.068 p=0.664, OKS >5 years p(df)=0.065 p= 0.709. For >2 year and > 5 year KOOS subscales there were no statistically significant associations on Spearman's rank. There were no adverse outcome in patients up-to the age of 71. There were no statistically significant Spearman's rank correlations between PROMS and OKS/KOOS scores. This supports recent KOG consensus statement highlighting physiological age importance vs chronological age. Of note there were more negative associations in the BMI group compared with age

This study aimed to examine the effect of high tibial osteotomy (HTO) on the ankle and subtalar joints via analysis of static radiographic alignment. We hypothesised that surgical alteration of the alignment of the proximal tibia would result in compensatory distal changes. 35 patients recruited as part of the wider Biomechanics and Bioengineering Centre Versus Arthritis HTO study between 2011 and 2018 had pre- and postoperative full-length weightbearing radiographs taken of their lower limbs. In addition to standard alignment measures of the limb and knee (mechanical tibiofemoral angle, Mikulicz point, medial proximal tibial angle), additional measures were taken of the ankle/subtalar joints (lateral distal tibial angle, ground-talus angle, joint line convergence angle of the ankle) as well as a novel measure of stance width. Results were compared using a paired T-test and Pearson's correlation coefficient. Following HTO, there was a significant (5.4°) change in subtalar alignment. Ground-talus angle appeared related both to the level of malalignment preoperatively and the magnitude of the alignment change caused by the HTO surgery; suggesting subtalar positioning as a key adaptive mechanism. In addition to compensatory changes within the subtalar joints, the patients on average had a 31% wider stance following HTO. These two mechanisms do not appear to be correlated but the morphology of the tibial plafond may influence which compensatory mechanisms are employed by different subgroups of HTO patients. These findings are of vital importance in clinical practice both to anticipate potential changes to the ankle and subtalar joints following HTO but it could also open up wider indications for HTO in the treatment of ankle malalignment and osteoarthritis

Purpose: The aim of this study is the evaluation of the results of the treatment of knee osteoarthritis in varus knee with high tibial osteotomy. Method: Between 1985 – 1991, 54 patients (62 cases) were treated with high tibial osteotomy, which was fixed with A. Renieri technique. The patients were divided in three groups:. - patients who were further treated with TKR. - patients who died without any further surgical treatment. - patients who are still alive and were treated only with high tibial osteotomy. Our study showed that 15 patients (19 cases) needed TKR within mean time 7 years from the osteotomy, 14 patients(15 cases) died without any further surgical treatment in mean time 9 years from the osteotomy and 25 patients (28 cases) who are still alive were treated only with high tibial osteotomy and twelve years later the results are good in 66% and poor in 34%. Results: As shown from our study high tibial osteotomy with correction of the knee axis and changes of the weight bearing helped in the treatment of pain and delayed the development of knee osteoarthritis in 39 patients (43 cases), who are still alive or died without any further operation after the osteotomy. 15 patients (19 cases) needed TKR after 7 years mean time. Conclusions: Despite the satisfactory results of TKR, osteoarthritis of knee can be treated with high tibial osteotomy mainly in younger patients, so that TKR if needed, can be performed later. The operation is relatively easy with less complication rate and does not impend the possible TKR later

Introduction: The knee arthritis is a very common seen chronic disease in an orthopaedic practice. It is mostly seen in patients after 6 decade of life and connected with a severe knee pain. In most of the cases the surgical intervention is indicated because of unicondylar arthritis changes. Because of the costs of the hemiarthroplasty we choose a high tibial osteotomy for tibial axis correction to prevent further gonarthrosis. The aim of this study was to evaluate the late results after high tibial osteotomy in patients with unicondylar gonarthrosis. Material and Methods: In our Institution during last 20 years 94 high tibial osteotomy were performed because of unicondylar, medial gonarthrosis. The mean age of the patient at the time of surgery was 56 years (from 19 to 72 years). The mean follow-up was 16 years. Only patients with arthritic changes on the medial compartment of the knee with a “good” lateral part of the knee were scheduled for this type of surgery. In every case the dome type of osteotomy was performed followed by 1cm resection of fibula. After surgery the limb was stabilized with plate in 16 cases, K-wires in 4 cases, Ilizarov frame in 43 cases, orthofix device in 8 cases and other type of external fixator in remaining 23 cases. In patients where external fixator was used the full weight bearing was recommended as soon as patient tolerated the pain. The external fixator was removed after an average period of 6 weeks when bone callus was diagnosed. To assess of the clinical results based on HSS score and radiological results were evaluated using the modified Dihlmann classification. Results: In 88,8% of all cases the final result was graded as excellent and good, in 1,9% the final results was satisfactory and in 7.8% the final results was poor. From analyzed patients 46% was scheduled for TKR at an average time of 12 years after initial surgical procedure. In 28% after average 16 years after high tibial osteotomy the good shape of the knee joint was observed with good clinical function and radiographic appearance. Pain was reduced in 82% of all cases, increased range of the knee motion was observed in 65% and improved walking ability in 64% of all cases. The poor results were connected with not adequate patients selection for this type of surgery (patients after 7 decade of life) and with advanced arthritic knee changes before the surgery. Conclusions : The high tibial osteotomy is a good method for preventing gonarthrosis. When early performed gives good long-lasting result. In our opinion is recommended for unicondylar gonarthrosis as an alternative to the knee hemiarthroplasty

High tibial osteotomies are commonly performed for varus/valgus malalignment of the knee. In the past we have been well aware that a high tibial osteotomy corrects the coronal plane but we did not consider changes of the tibial slope. Altering the slope has an impact on the in situ forces of the cruciate ligaments and influences the stability of the knee. The purpose of this study was to investigate the amount of alteration of the tibial slope by a closed wedge osteotomy. From January 2001 to September 2001 we reviewed retrospectively all Xrays of patients that underwent a high tibial osteotomy or were admitted for removal of hardware. 80 patients were included. 67 patients could be followed up. The slope on the preoperative xrays was 6,1 degrees (0–12). A closed wedge osteotomy decreased the slope by a mean of 4,88 degrees. A high tibial osteotomy of six degrees in the coronal plane decreased the slope by 4.29 degrees, a HTO of eight degrees decreased the slope by 7 degrees, a HTO of ten degrees by altered the slope by 4.75 and of twelve degrees by decreased the slope by 6.5 degrees. A closed wedge osteotomy decreases the tibial slope. It is the preferred technique when a combined procedure (HTO and ACL reconstruction) is planned. There is no correlation between the degree of correction of the coronal plane by a closed wedge high tibial osteotomy and changes of the tibial slope

Unicompartmental knee arthroplasty (UKA) and high tibial osteotomy (HTO) are well-established operative interventions in the treatment of knee osteoarthritis (KOA). However, which of these interventions is more beneficial, to patients with KOA, is not known and remains a topic of much debate. Aims: (i) To determine whether UKA or HTO is more beneficial in the treatment of isolated medial compartment KOA, via an assessment of patient-reported outcome measures (PROMs). (ii) To investigate the relationship between PROMs and radiographic parameters of knee joint orientation/alignment. This longitudinal observational study assessed a total of 42 patients that had undergone UKA (n=23) or HTO (n=19) to treat isolated medial compartment KOA. The PROMs assessed, pre-operatively and 1-year post-operatively, consisted of the: self-administered comorbidity questionnaire; short form-12; oxford knee score; knee injury and osteoarthritis outcome score; and the EQ-5D-5L. The radiographic parameters of knee joint alignment/orientation assessed, pre-operatively and 8-weeks post-operatively, included the: hip-knee-ankle angle; mechanical axis deviation; and the angle of the Mikulicz line. Statistical analysis demonstrated an overall significant (p<0.001), pre-operative to post-operative, improvement in the PROM scores of both groups. There were no significant differences in the post-operative PROM scores of the UKA and HTO group. Correlation analyses revealed that pre-operatively, a more distolaterally angled Mikulicz line was associated with worse knee function (p<0.05) and overall health (p<0.05); a relationship that, until now, has not been investigated nor commented upon within the literature. UKAs and HTOs are both efficacious operations that provide a comparable degree of clinical benefit to patients with isolated medial compartment KOA. To further the scientific/medical community's understanding of the factors that impact upon health-outcomes in KOA, future research should seek to investigate the mechanism underlying the relationship, between Mikulicz line and PROMs, observed within the current study

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

Tibial osteotomy is a time-honored procedure in the treatment of medial femorotibial osteoarthritis. However new points need to be discussed in a modern approach of this technique. What factors have a bearing on the decision and the technique ? During this symposium will be discussed: the advantages of the tibial opening versus closing wedge; the possibility to avoid bone grafts by using bone ceramics for opening wedge osteotomies; the importance of reliable fixation technique; the importance of decreasing the posterior slope of the tibia if the osteotomy is done on a knee with an anterior cruciate deficiency. How long is tibial osteotomy effective and what are the outcome of postosteotomy procedures after failure of the osteotomy: most of the data indicate that tibial osteotomy is very often effective and, that achieving a moderate degree of valgus is a decisive factor in the long term osteotomy survival. However since the patients are young at the tissue of the osteotomy and since the results deteriorate over the time, the subsequent procedures should be discussed. Can a second osteotomy be done after failure of the first osteotomy ? Is it possible to perform a unicompartmental arthroplasty after a high tibial osteotomy ? What are the technical problems of a total knee arthroplasty after a high tibial osteotomy ?

Medial opening wedge high tibial osteotomy (MOWHTO) is the workhorse procedure for correcting varus malalignment of the knee. There have been recent developments in the synthetic options to fill the osteotomy gap. The current gold standard for filling this osteotomy gap is autologous bone graft which is associated with donor site morbidity. We would like to introduce and describe the process of utilizing the novel Osteopore® 3D printed, honeycomb structured, Polycaprolactone and β-Tricalcium Phosphate wedge for filling the gap in MOWHTO. In the advent of additive manufacturing and the quest for more biocompatible materials, the usage of the Osteopore® bone wedge in MOWHTO is a promising technique that may improve the biomechanical stability as well the healing of the osteotomy gap

Purpose: This study documents the short term follow-up of a group of patients with unicompartmental osteoarthritis with associated collateral ligament laxity. there are currently few studies documenting the indication and results of open wedge high tibial osteotomy. Methods: A retrospective assessment of 52 cases of open wedge high tibial osteotomy ws carried out of cases performed between 1999–2003. The average follow-up was 4.5 years and the mean age was 38 years. We selected cases with varus alignment and laxity of the medial collateral ligament. Clinical evaluation was carried out using the HSS knee rating score. Clinical laxity pre and post-op was noted, as well as range of motion, quads bulk and swelling. Pre and post-op 3 foot standing x-rays were carried out to assess alignment.|The Puddu open wedge osteotomy was used in all cases with autogenous bone from the iliac crest. Supplemental fixation of the opposite side of the tibia was used if there was any tendency to open. Results: Open wedge high tibial osteotomy for unicompartmental osteoarthritis with ligament laxity treats both problems. The change in alignment deals with the arthritic symptoms and the opening wedge tensions the collateral ligament.|Of the 52 cases, 44 are good to excellent with 2 non-unions and 3 cases converted to total knee replacement. Conclusions: Open wedge high tibial osteotomy can deal effectively with selected cases of unicompartmental osteoarthritis with secondary collateral ligament laxity

Introduction. In contrast to knee arthroplasty, there is no national register on high tibial osteotomy (HTO) in Sweden. The knowledge of the outcome of HTO as a treatment alternative for knee osteoarthritis (OA) is insufficient. The rate of revision to knee arthroplasty after HTO at 10 years has been reported to vary between 8 and 49%. The aim of the study was to evaluate the outcome of HTO performed in Sweden 1998–2007, expressed by rate of revision to knee arthroplasty. Patienter och Material: 3 196 HTO (69% men) 30 years or older operated on for knee OA in Sweden 1998–2007 were identified through the in- and out-patient care registers from the Swedish National Board of Health and Welfare. Side, left/right, that was operated, diagnosis and indication for surgery were verified through surgical records. Conversions of HTO to knee arthroplasty before 2010 were identified through the Swedish Knee Arthroplasty Register (SKAR). In about 10% of the cases it was unknown what side the HTO had been performed on and thus if the arthroplasty had been on the same knee. In these cases we assumed a worst case scenario of all having been on the same side as the HTO. A 10-year survival analysis was performed using revision to an arthroplasty as the end point. Result. The mean age was 52 years (range 30- 80) with 97% of the patients younger than 65 years. The cumulative revision rate (CRR) at 10 year was 29.4% (95% CI 27.2–32.9) after adjusting for age and gender. The risk of revision increased by increasing age and the risk of revision after adjusting for age was significantly higher in women than men RR 1.30 (95% CI 1.11–4.54). Most of the HTO's were performed by open wedge osteotomy using external fixation. The risk of revision was higher for closed wedge osteotomies when comparing the closed and open wedge methods RR1.29 (95% CI 1.08–1.55). Conclusion. 70% of the high tibial osteotomies performed in Sweden 1998–2007 had not been converted to a knee replacement, using the 10 year cumulative revision rate. If it is considering beneficial to have no implant in the knee, high tibial osteotomy may be considered as an alternative to TKA in the younger and physically active patients

Objectives. Opening wedge high tibial osteotomy (HTO) is an established surgical procedure for the treatment of early-stage knee arthritis. Other than infection, the majority of complications are related to mechanical factors – in particular, stimulation of healing at the osteotomy site. This study used finite element (FE) analysis to investigate the effect of plate design and bridging span on interfragmentary movement (IFM) and the influence of fracture healing on plate stress and potential failure. Materials and Methods. A 10° opening wedge HTO was created in a composite tibia. Imaging and strain gauge data were used to create and validate FE models. Models of an intact tibia and a tibia implanted with a custom HTO plate using two different bridging spans were validated against experimental data. Physiological muscle forces and different stages of osteotomy gap healing simulating up to six weeks postoperatively were then incorporated. Predictions of plate stress and IFM for the custom plate were compared against predictions for an industry standard plate (TomoFix). Results. For both plate types, long spans increased IFM but did not substantially alter peak plate stress. The custom plate increased axial and shear IFM values by up to 24% and 47%, respectively, compared with the TomoFix. In all cases, a callus stiffness of 528 MPa was required to reduce plate stress below the fatigue strength of titanium alloy. Conclusion. We demonstrate that larger bridging spans in opening wedge HTO increase IFM without substantially increasing plate stress. The results indicate, however, that callus healing is required to prevent fatigue failure. Cite this article: A. R. MacLeod, G. Serrancoli, B. J. Fregly, A. D. Toms, H. S. Gill. The effect of plate design, bridging span, and fracture healing on the performance of high tibial osteotomy plates: An experimental and finite element study. Bone Joint Res 2018;7:639–649. DOI: 10.1302/2046-3758.712.BJR-2018-0035.R1

Introduction and Aims: High tibial osteotomy (HTO) is a corrective surgical procedure used to treat medial compartment osteoarthritis (OA). In HTO a bone wedge is resected from the upper tibia to realign the lower limb. In this study, we investigated the effect of HTO on patellofemoral joint motion using a validated new technique. Method: We assessed patellar tracking in four subjects before and after high tibial osteotomy surgery. A high-resolution MR image was acquired of each subject’s knee. Each subject then loaded his/her knee in a custom test rig in the MR scanner, while fast, low-resolution MRI scans were acquired. This was repeated at five flexion angles. Bone outlines were identified (image segmentation) and processed (meshed) to yield bone models. Knee kinematics were determined by matching (registering) the high-resolution bone models to the low-resolution bony outlines. We compared the pre- and post-operative tracking patterns using a two-way repeated measures ANOVA. Results: The resultant patellar tracking patterns were expressed as a function of knee flexion. Mean values for each quantity were calculated over the flexion range. High tibial osteotomy decreased patellar flexion by a mean of 5.06 degrees (p < 0.003), decreased internal patellar spin by a mean of 1.25 degrees (p < 0.001) and increased medial patellar tilt by a mean of 1.59 degrees (p < 0.001). High tibial osteotomy increased proximal patellar translation by a mean of 4.19mm (p < 0.008), but, for the number of specimens tested, we found no significant change in anterior or medial translation. Conclusion: Our finding that HTO translated the patella proximally is consistent with findings of elevated patellae in the literature. The significant changes in patellar movement caused by high tibial osteotomy surgery suggest that the post-operative anterior knee pain associated with these procedures is due to mechanical changes at the patellofemoral joint

Introduction: One of the problems of high tibial valgus osteotomy is the loss of achieved correction, which, in turn, is associated with the deterioration of the patient’s symptoms. Aim: The aim of the present retrospective study is the correlation of certain parameters of axial alignment of the knee joint with the possibility of varus recurrence, after high tibial osteotomy, with stable fixation. Material – Method: For this purpose we studied 33 patients (37 knees), that had undergone high tibial osteotomy between 1989 and 1997. All the above patients had a follow up of at least 2 years, with a mean of 35 months. The axial parameters that were studied were the femoral condyle-femoral shaft angle, the tibial plateau-tibial shaft angle, the post operative valgus correction and the post operative medial joint space widening. Results: Loss of femorotibial angle equal to or more than 3 degrees was regarded as recurrence. This was observed in 9 knees (24%). The possibility of recurrence was strongly associated (Logistic Regression Analysis), on the one hand, with a post operative valgus correction of less than 6 degrees, and, on the other hand, with a femoral condyle-femoral shaft angle of more than 84 degrees (varus orientation of the articular surface of femoral condyles). Conclusion: It seems that both undercorrection of the femorotibial angle and varus orientation of the femoral condyles in the frontal plane do not allow the shift of the weight bearing axis of the lower extremity towards the lateral compartment and, thus, constitute risk factors for recurrence of the varus deformity