Mechanical Tibiofemoral Angle Research Articles

Outcomes After Osteochondral Allograft Transplantation of the Medial Femoral Condyle in Patients With Varus and Nonvarus Alignment

Background: Fresh osteochondral allograft (OCA) transplantation is an effective technique for the treatment of focal chondral and osteochondral defects in the knee. Coronal-plane malalignment leads to increased contact forces within a compartment and subsequently the cartilage repair site and may lead to higher failure rates. However, the magnitude of the effect of coronal-plane malalignment on graft survivorship and clinical outcomes has not been well characterized. Purpose: To evaluate how varus malalignment affects graft survival and patient-reported outcomes after isolated OCA transplantation of the medial femoral condyle (MFC). Study Design: Cohort study; Level of evidence, 3. Methods: A total of 70 patients (74 knees) who underwent primary OCA transplantation of the MFC between 2005 and 2019 were identified from a prospectively collected single-surgeon cartilage registry with a minimum 2-year follow-up. Coronal-plane alignment was evaluated utilizing standing hip-to-ankle radiographs. OCA failure, defined as removal of the graft or conversion to arthroplasty, and reoperations were recorded. Patient-reported outcomes were obtained preoperatively and postoperatively using the International Knee Documentation Committee score, Knee injury and Osteoarthritis Outcome Score, modified Merle d’Aubigné–Postel score, and overall patient satisfaction score. Results: The mean mechanical tibiofemoral angle for patients with varus alignment was 3.9° of varus (range, 1.1° to 8.9°) and for patients with nonvarus alignment it was 0.02° of valgus (range, 3.6° varus to 4.6° valgus). Graft survivorship was 95.3% in the varus group and 95.8% in the nonvarus group (P = .918) at 5 years postoperatively. Reoperations after OCA transplantation occurred in 14.0% of the varus group and 22.6% of the nonvarus group (P = .336). The mean International Knee Documentation Committee total score improved from 45.2 preoperatively to 74.8 at latest follow-up in the varus group and from 40.5 preoperatively to 72.3 at latest follow-up in the nonvarus group. Patient satisfaction was >85%. Conclusion: Patients undergoing isolated OCA transplantation of the MFC had high rates (>90%) of graft survivorship and significant improvements in pain and function. Patients with mild preexisting varus malalignment were found to have no difference in the failure rate or clinical outcomes compared with patients with nonvarus alignment.

Medial open wedge high tibial osteotomy is a viable option in young patients with advanced arthritis in a long-term follow-up.

This study aimed to evaluate the long-term outcomes of medial open wedge high tibial osteotomy (MOWHTO) as a treatment option for advanced medial compartment knee osteoarthritis (OA) Kellgren-Lawrence (K-L) III and IV. Patients with severe medial compartment arthritis, who underwent MOWHTO with locking plate between 2003 and 2015, were retrospectively reviewed. A locking plate for the osteotomy was utilized. Preoperative and postoperative patients' evaluation was performed using the International Knee Documentation Committee Score (IKDC), the Oxford Knee Score (OKS), the Knee Injury Osteoarthritis Outcome Score (KOOS) and the Short Form-12 Score (SF-12). Standardized standing whole-limb X-rays were taken to evaluate the mechanical tibiofemoral angle (mTFA) and proximal medial tibial angle (PMTA), and the severity of OA. A total of 32 patients, 35 knees (27 males, five females) of which 21 were classified as K-L Grade III and 14 as K-L Grade IV, and mean age 47.1 ± 9.17 years old, who were followed for 13.6 years (range 7-20 years), were included in the study. During the follow-up period, three knees required conversion to total knee replacement (91.5% survival rate). All clinical outcome scores (KOOS, OKS, IKDC and SF-12) showed a significant improvement compared to preoperative status (p < 0.05). Preoperative mTFA and PMTA were significantly corrected immediately after surgery and retained this improvement at the last follow-up. MOWHTO with a locking plate is an effective method to treat severe medial compartments. Clinical and radiological results are satisfactory and the survival rate is 91.5%, at a mean follow-up of 13.6 years after the procedure. Level IV.

Medial opening wedge high tibial osteotomy performs similarly irrespective of body mass index.

This study investigates the effect of the body mass index (BMI) on the early (2 years) to midterm (5 years) results of medial opening wedge high tibial osteotomy (MOWHTO). A prospectively maintained single-centre database of 1138 knee osteotomies, between 2002 and2022, was retrospectively reviewed. Adult patients who underwent MOWHTO for symptomatic unicompartmental medial knee osteoarthritis (OA), with varus knee malalignment, having failed conservative management, were included. Patients were categorized into threegroups according to their BMI as per the classification from the National Institute for Health and Care Excellence (NICE): the healthy weight (HW) group (BMI of 18.5-24.9 kg/m2), the overweight (OW) (BMI of 25-29.9 kg/m2), and the obesity (OB) group (BMI ≥ 30 kg/m2). Multiple patient-reported outcome measures (n = 6) were recorded preoperatively and at 2 and 5 years postoperatively. Deformity analysis was undertaken preoperatively and postoperatively. The relative risk (RR) of the complications between the HW, OWand OB groups was calculated. The rate of conversion to arthroplasty, and 5and 10 years survivorship were recorded, as well as the hazard ratio (HR) of BMI on survivorship. A total of 574 cases were included in the study: the HW group (n = 96), the OW group (n = 233)and the OB group (n = 245), with a mean BMI of 23 ± 1.5 kg/m2, 27.4 ± 1.4 kg/m2 and 34.4 ± 3.8 kg/m2, respectively. The mean follow-up was 13.3 years (4.8-20.3). The mean mechanical tibiofemoral angle corrections were in the HW group: 7.1 ± 3°, OW group: 6.6 ± 3.5°and OB group: 7.1 ± 3.8°, with no intergroup significant difference (p = n.s.). Clinically, despite lower preoperative scores in the OW and OB groups, no difference was observed postoperatively amongst the three groups. The overall complication rate was 12.5% in the HW group, 6.8% in the OW group, and 9.8% in the OB group. There was no significant difference in the RR of complications between the HW and OW groups (RR = 0.6, 95% confidence interval [CI] = 0.3-1.3)(p = 0.2), and the HW and OB groups (RR = 0.8; 95% CI = 0.3-2.2)(p = 0.7). There was no overall significant difference in survival outcomes based on the BMI between the threegroups (p = 0.4). The HR of conversion to arthroplasty between the HW and OW groups was 1.4 [95% CI = 0.6-3.5](p = 0.5)and between the HW and OB groups was 1.8 [95% CI = 0.8-4.4] (p = 0.2). BMI has no significant effect on either the radiological corrections, clinical outcomes, complicationsor survivorship of MOWHTO at short- to medium-term follow-up. No specific cutoff point for BMI can be recommended as a contraindication to MOWHTO. Level IV, Retrospective cohort study.

Surgical Technique and Preliminary Outcomes of Double-Level Osteotomy for Valgus Deformity.

Data are limited regarding the surgical technique or outcomes of double-level osteotomy (DLO) combining medial closing-wedge distal femoral osteotomy and medial closing-wedge high tibial osteotomy in patients with moderate-to-severe valgus deformity. To describe the surgical technique and assess the short-term outcomes and surgical accuracy of DLO in patients with a moderate or severe valgus deformity. It was hypothesized that this technique would result in good clinical outcomes with precise deformity correction. Case series; Level of evidence, 4. Eight patients (mean age, 44.2 ± 10.9 years) with a moderate or severe valgus knee treated with DLO (9 knees; mechanical tibiofemoral angle [mTFA], 10.3°± 3.5°) were included. The mean follow-up was 25.1 ± 11.1 months. Preoperative to postoperative changes in radiographic parameters (mTFA, mechanical lateral distal femoral angle, mechanical medial proximal tibial angle, joint line convergence angle) and clinical scores (Hospital for Special Surgery score, Oxford Knee Score, Lysholm score) were assessed. Surgical accuracy was calculated by subtracting the achieved postoperative correction from the preoperatively planned targeted correction. The mTFA changed significantly from 10.3°± 3.5° preoperatively to -1.8°± 3.4° postoperatively (P < .001); the mechanical lateral distal femoral angle and mechanical medial proximal tibial angle changed significantly by 5.1°± 2.7° and 5.9°± 2.2°, respectively (P < .001 for both); and the posterior distal femoral angle decreased significantly from 85.9°± 3.1° to 84.2°± 2.4° (P < .01). There was no significant difference between pre- and postoperative joint line convergence angles (3.3°± 2.3° to 2.6°± 2.1°). The accuracy of the correction was high: the mTFA achieved postoperatively differed from the mTFA planned preoperatively by a mean of 2.7°± 1.9° (range, 0.6°-6.6°). Significant pre- to postoperative improvement was seen for all outcome scores (Hospital for Special Surgery, from 67 ± 11 to 93 ± 4; Oxford Knee Score, from 29 ± 7 to 43 ± 3; Lysholm, from 41 ± 24 to 89 ± 8; P < .001 for all). High surgical accuracy was achieved, and patients who underwent varus DLO for valgus knees showed improved knee function at short-term follow-up. Varus DLO can be a surgical option to restore the optimal alignment and joint line obliquity in patients with moderate or severe valgus malalignment.

Neutral to slightly undercorrected mechanical leg alignment provides superior long-term results in patients undergoing matrix-associated autologous chondrocyte implantation.

The aim of this study was to evaluate the role of leg alignment on long-term clinical outcomeafter matrix-associated autologous chondrocyte implantation (M-ACI) and to define an individualized target range to optimize clinical outcome. The present study examined patients who underwent M-ACI of the femoral condyle. The Knee Injury and Osteoarthritis Outcome Score (KOOS) and Magnetic Resonance Observation of Cartilage Repair Tissue (MOCART) were used to assess the results. Clinical outcomes were related to Patient Acceptable Symptomatic State (PASS). For intra- and interobserver reliability of mechanical tibiofemoral angle, mechanical medial proximal tibial angleand mechanical lateral distal femoral angle, we calculated intraclass correlation coefficientsusing a two-way mixed model with absolute agreement. A regression model and receiver-operating characteristics curve were used to identify an individual range of alignment where a favourable clinical outcome could be expected in the long term. Additional osteotomy was performed in 50% of patients with similar clinical outcomes as physiologically aligned patients (p > 0.05). The curve-fitting regression model identified a target range of -2.5° valgus to 4.5° varus for ideal postoperative alignment (R2 = 0.12, p = 0.01). Patients within this range were more likely to achieve PASS (70% vs. 27%, p = 0.001). In medially treated defects, a refined range of -2.5° valgus to 4° varus alignment was found (R2 = 0.15, p = 0.01). These patients were more likely to achieve PASS (67% vs. 30%, p = 0.01) and showed favourable postoperative KOOS and MOCART scores (p = 0.02). Patients with lateral defects were more likely to achieve PASS within a range of -2° valgus and 0.5° varus (90% vs. 45%, p = 0.03) and showed favourable postoperative KOOS and MOCART scores (p = not significant). An individual range of leg alignment-whether achieved by osteotomy or physiologic alignment-should be respected in M-ACI treatment. A neutral to slightly undercorrected alignment favours the postoperative outcome after M-ACI. When planning surgery for patients with focal cartilage defects of the femoral condyle, these ranges should be recognized as critical factors. Level III.

Comparison of Side-to-Side Difference in Posterior Tibial Slope in Knees With Acute Versus Chronic Anterior Cruciate Ligament Deficiency.

The posterior tibial slope (PTS) is an important feature in knee joint biomechanics and indicates anterior-posterior knee stability. Increased PTS is a known risk factor for both primary anterior cruciate ligament (ACL) rupture and postreconstruction rerupture. To investigate the effect of long-term exposure to ACL deficiency on the PTS and the sagittal anatomy of the proximal tibia. Cross-sectional study; Level of evidence, 3. A total of 44 patients (38 men, 6 women) with a history of knee injury and ACL rupture confirmed by magnetic resonance imaging and physical examination were included in this study. Patients were divided into those with chronic ACL deficiency (group 1: injured ≥5 years prior; n = 22) and acute ACL deficiency (group 2: injured <1 year prior; n = 22). The medial and lateral tibial plateau PTS and anterior tibial translation were measured on monopodal weightbearing knee radiographs at 20° of flexion. The mechanical tibiofemoral angle (MTFA) and the medial proximal tibial angle (MPTA) were measured using an orthoroentgenogram. The side-to-side difference between the affected and unaffected knees was also calculated for all measurements. The mean duration of exposure to ACL deficiency was 7.6 years (range, 5-15 years) in group 1 and 4.4 months (range, 1-11 months) in group 2. Regarding the side-to-side differences in angular measurements, a higher medial PTS (affected vs unaffected: 12.4° vs 10.1°; P = .007), higher lateral PTS (11° vs 8.9°; P = .011), and increased varus alignment on both the MTFA (4.3° vs 2.4°; P = .036) and the MPTA (84.9° vs 86.3°; P = .033) were found in group 1, while no significant differences in angular measurements were found in group 2. Compared with group 2, patients in group 1 had a significantly higher side-to-side difference in the medial PTS (2.3° vs 0.1°; P = .0001), lateral PTS (2.1° vs 0.4°; P = .0001), and MPTA (1.4° vs 0.1°; P = .002). This study showed that the affected knees of patients with chronic ACL deficiency (≥5 years) had higher medial and lateral PTS compared with the unaffected contralateral knees. Therefore, when planning ACL reconstruction for patients with a history of long-term ACL deficiency, it is crucial to measure the preoperative PTS accurately.

Automated analysis of knee joint alignment using detailed angular values in long leg radiographs based on deep learning

Malalignment in the lower limb structure occurs due to various causes. Accurately evaluating limb alignment in situations where malalignment needs correction is necessary. To create an automated support system to evaluate lower limb alignment by quantifying mechanical tibiofemoral angle (mTFA), mechanical lateral distal femoral angle (mLDFA), medial proximal tibial angle (MPTA), and joint line convergence angle (JLCA) on full-length weight-bearing radiographs of both lower extremities. In this retrospective study, we analysed 404 radiographs from one hospital for algorithm development and testing and 30 radiographs from another hospital for external validation. The performance of segmentation algorithm was compared to that of manual segmentation using the dice similarity coefficient (DSC). The agreement of alignment parameters was assessed using the intraclass correlation coefficient (ICC) for internal and external validation. The time taken to load the data and measure the four alignment parameters was recorded. The segmentation algorithm demonstrated excellent agreement with human-annotated segmentation for all anatomical regions (average similarity: 89–97%). Internal validation yielded good to very good agreement for all the alignment parameters (ICC ranges: 0.7213–0.9865). Interobserver correlations between manual and automatic measurements in external validation were good to very good (ICC scores: 0.7126–0.9695). The computer-aided measurement was 3.44 times faster than was the manual measurement. Our deep learning-based automated measurement algorithm accurately quantified lower limb alignment from radiographs and was faster than manual measurement.

The Effect of Valgus Deformity Degree of Knee Osteoarthritis Patients on Tibiofemoral Angle Mechanical Output and Knee Society Score After Total Knee Arthroplasty Non-Constrained at Prof. Dr. I.G.N.G Ngoerah Hospital

Background: Osteoarthritis (OA) is a progressive musculoskeletal problem causing a loss of articular cartilage and damage to cellular and biomechanical components. In Indonesia, the prevalence of OA is 36.5 million people, with 40% over 70 years old and 80% with limited movement. Malalignment in the knee joint, found in almost 10% of patients undergoing total knee arthroplasty (TKA) surgery, is a challenge for orthopedic surgeons. Factors such as body weight, high BMI, work history, malalignment, and synovitis are associated with the development of knee OA. Total Knee Arthroplasty (TKA) is a surgical procedure to overcome OA problems in the knee joint, but deformities affect the success of TKA surgery. Researchers aim to determine if there is an association between valgus deformity in knee OA patients and tibiofemoral angle correction and Knee Society Score 12 weeks after TKA. Methods: The study involved 42 patients with primary knee osteoarthritis and valgus deformity who underwent primary Total Knee Replacement (TKR) at Prof. Dr. Ngoerah Hospital. The study included patients with grade III-IV Kellgren-Lawrence knee osteoarthritis, underwent primary TKA, and had lower extremity scans before and 12 weeks postoperatively. Functional and clinical outcomes were measured using mechanical tibiofemoral angle and Knee Severity Score. Results: The study involved 21 female patients with OA Ranawat 2 and a 7:1 ratio of male and female participants. The most common OA was in the right knee. After TKR, there was no significant difference in MTFA and KSS scores between patients. However, after 12 weeks, the average MTFA score decreased to 8.57, with a significant change before and after the surgery. Keywords: Osteoarthritis, total knee arthroplasty (TKA), Kellgren-Lawrence.

High survivorship and low complication rate in a single-centre series of 651 medial opening wedge high tibial osteotomy cases with a mean follow-up of 13 years.

This study aimed to report the early to midterm results of medial opening wedge high tibial osteotomy (MOWHTO) from the largest single-centre osteotomy database. The primary outcomes were reporting the radiological corrections and the functional outcomes represented by multiple patient-reported outcome measures (PROMs). The secondary outcomes were to report the complications, revisionsand survivorship up to 10 years postoperatively. A prospectively maintained single-centre database of 1138 knee osteotomies was retrospectively reviewed. Patients who underwent MOWHTO and met the inclusion criteria were included. Those inclusion criteria were moderate to severe knee pain that failed conservative management;varus knee malalignment; and isolated medial osteoarthritis of the knee. A total of 651 cases, with a mean age of 46.7 ± 9 years and a mean body mass indexof 29.6 ± 5.2 kg/m2 , were included. This comprised 71% males (n = 462) and 29% females (n = 189). The mean follow-up was 158.1 ± 45.4 months. Multiple PROMs were recorded preoperatively and serially postoperatively. This included the Knee injury andOsteoarthritisOutcome Scores, the Oxford Knee Score, the Oxford Knee Score-Activity and Participation Questionnaire, the Western Ontario and McMaster University Scores, the Visual Analogue Scale for health and pain, and the EQ-5D, which is a standardised measure of health-related quality of life. All lower limb alignment measurements were recorded pre- and postoperatively. The rates of osteotomy revision, conversion to arthroplasty, complications, and 5- and 10-year survivorship were recorded. A total of 651 cases were followed up to a mean of 158.1 ± 45.4 months. The mean planned correction angle was 7.6° ± 2.9°. The mean planned opening wedge distance was 8.1 ± 3.1 mm. The mean intraoperative anterior and posterior osteotomy gaps opening were 7.7 ± 3.4and 8.9 ± 3.8 mm, respectively. Postoperatively, the mean mechanical tibiofemoral angle improved from -5.7° ± 2.9° varus to 1.3° ± 2.5° valgus, the mean medial proximal tibial angle improved from preoperative 85.5° ± 2.3° to postoperative 91.6° ± 2.7°and the mean Mikulicz point improved from 21.7 ± 12.6% to 54.8 ± 11% (all p values < 0.001). All PROMs significantly improved at 24 months follow-up (all p values < 0.001). The rate of osteotomy revision was 1.1% at a mean of 2 ± 2.5 years postoperatively. The overall rate of arthroplasty conversion was 9.1%. This comprised 5.8% total knee arthroplasty conversion at a mean of 6.9 ± 3.5 years postoperatively and 3.2% unicompartmental knee arthroplasty conversion at a mean of 5.7 ± 2.5 years postoperatively. An overall 10.3% complication rate was recorded. The 5 and 10-year survivorship was 97.2%and 91.9%, respectively. MOWHTOis a radiologically and clinically rewarding procedure with a high survival rate at 5 and 10 years and a low complication rate in experienced hands. MOWHTO should be considered in patients presenting with medial unicompartmental knee pain with an evidence of overload and a varus mechanical coronal plane axis. Level IV, retrospective cohort study.

Increased ankle pain after total knee arthroplasty is associated with a preoperative lateralized gait and talar tilt, but not with ankle laxity or the range of motion of the subtalar joint.

Total knee arthroplasty (TKA) may provoke ankle symptoms. The aim of this study was to validate the impact of the preoperative mechanical tibiofemoral angle (mTFA), the talar tilt (TT) on ankle symptoms after TKA, and assess changes in the range of motion (ROM) of the subtalar joint, foot posture, and ankle laxity. Patients who underwent TKA from September 2020 to September 2021 were prospectively included. Inclusion criteria were primary end-stage osteoarthritis (Kellgren-Lawrence stage IV) of the knee. Exclusion criteria were missed follow-up visit, post-traumatic pathologies of the foot, and neurological disorders. Radiological angles measured included the mTFA, hindfoot alignment view angle, and TT. The Foot Function Index (FFI) score was assessed. Gait analyses were conducted to measure mediolateral changes of the gait line and ankle laxity was tested using an ankle arthrometer. All parameters were acquired one week pre- and three months postoperatively. A total of 69 patients (varus n = 45; valgus n = 24) underwent TKA and completed the postoperative follow-up visit. Of these, 16 patients (23.2%) reported the onset or progression of ankle symptoms. Varus patients with increased ankle symptoms after TKA had a significantly higher pre- and postoperative TT. Valgus patients with ankle symptoms after TKA showed a pathologically lateralized gait line which could not be corrected through TKA. Patients who reported increased ankle pain neither had a decreased ROM of the subtalar joint nor increased ankle laxity following TKA. The preoperative mTFA did not correlate with the postoperative FFI (r = 0.037; p = 0.759). Approximately one-quarter of the patients developed ankle pain after TKA. If patients complain about ankle symptoms after TKA, standing radiographs of the ankle and a gait analysis could help in detecting a malaligned TT or a pathological gait.

Two years follow-up of patients with knee varus deformity and medial meniscus extrusion after medial opening wedge high tibial osteotomy and arthroscopic meniscus centralization.

This is a retrospective study and aims to investigate the clinical outcomes of patients with knee varus deformity and extruded medial meniscus who underwent arthroscopic meniscus centralization and medial opening wedge high tibial osteotomy. A total of 24 patients were included in the trial, and arthroscopy intraoperative photographs and standing preoperative and postoperative radiographs were taken to analyze the mechanical tibiofemoral angle and tibial plateau inclination. Postoperative complications and knee motion were recorded, and the surgical results were evaluated using the knee society score. The study observed four cases of surgery-related complications among all patients, but no major complications were reported. The surgery significantly improved knee flexion degrees and total knee range of motion. Satisfactory outcomes were shown in postoperative radiographs and secondary intraoperative photographs. The knee score increased from 39.6 ± 10.0 to 80.1 ± 9.0, and the functional score improved from 48.1 ± 6.9 to 89.4 ± 5.5. The preoperative tibial plateau inclination was 5.3 ± 0.7, while the postoperative data showed a decrease to 4.2 ± 0.7. The preoperative mechanical tibiofemoral angle was - 7.7 ± 1.0, and it improved in all patients postoperatively to 2.8 ± 0.9. By alternating the knee biomechanics and significantly improving symptoms and quality of life, arthroscopic medial meniscus centralization and medial open wedge high tibial osteotomy units are confirmed to be an effective alternative treatment for knee varus deformity.

Long-term Outcomes after Medial Open Wedge High Tibial Osteotomy - A Retrospective Study of 69 Patients.

High tibial osteotomy (HTO) is a widespread option to avoid or delay total knee arthroplasty (TKA). The present study aimed to assess the long-term survival rate and postoperative subjective knee function after isolated medial open wedge HTO in patients with symptomatic medial compartment knee osteoarthritis (OA) and varus malalignment.Sixty-nine patients (48.8±6.7, 35-66 years; preoperative mechanical tibiofemoral angle [mTFA] -5.3±3.4; -14.9-0.0° varus) treated with medial open wedge HTO using a TomoFix plate were included in this retrospective study, with a follow-up of at least 10 years (11.8±1.0 years). The survival rate after HTO was calculated after 5 and 10 years. Subjective knee function was assessed using Hospital for Special Surgery (HSS), Oxford knee, Lequesne, and Lysholm scores.Thirty-three patients underwent conversion to TKA, on average, 7.0±3.4 (1.3-13.7) years after HTO. Five- and ten-year survival rates were 84.1 and 60.9%, respectively. Patients without conversion to TKA showed a Lysholm score of 64.5 (35-92), Lequesne score of 7 (1-13), HSS score of 71 (56-86), and Oxford knee score of 38.5 (25-44) at the last follow-up (more than 10 years). Significantly higher scores were registered at the last follow-up compared to the preoperative state regarding the Lysholm score (preoperative: 43.5 [12-95]; follow-up: 64.5 [35-92]; p<0.001). The HSS score (preoperative: 69.5 [43-93]; follow-up: 71 [56-86]; p=0.6941) showed no statistically significant change during the 10-year follow-up period. The Lequesne score was significantly lower than the preoperative score (preoperative: 11.5 [0.5-22]; follow-up: 7 [1-13]; p<0.001), indicating a lower handicap.The majority of patients with a valgus medial compartmental knee OA treated with HTO with fixation using the TomoFix plate can expect no conversion to TKA for more than 10 years. Furthermore, patients without conversion to TKA after 10 years still had a significantly higher subjective knee function than preoperatively. Further research is needed to identify risk factors for conversion to TKA. This helps to guide surgeons in selecting patients who will benefit most from HTO.

MAKO robot-assisted total knee arthroplasty cannot reduce the aggravation of ankle varus incongruence after genu varus correction ≥ 10°: a radiographic assessment

IntroductionThe objective of this study was to investigate the ankle alignment alterations after the correction of knee varus deformity in MAKO robot-assisted total knee arthroplasty (MA-TKA).MethodsA retrospective analysis was conducted for 108 patients with TKA from February 2021 to February 2022. Patients were divided into two groups based on MAKO robot involvement during the procedure: the MA-TKA group (n = 36) and the conventional manual total knee arthroplasty (CM-TKA) group (n = 72). The patients were divided into four subgroups according to the degree of surgical correction of the knee varus deformity. Seven radiological measurements were evaluated pre and post-surgery: mechanical tibiofemoral angle (mTFA), mechanical lateral distal femoral angle (mLDFA), medial proximal tibial angle (MPTA), lateral distal tibial angle (LDTA), tibial plafond inclination angle (TPIA), talar inclination angle (TIA), and tibiotalar tilt angle (TTTA). TTTA is a quantitative representation of the extent of ankle incongruence.ResultsThe number of mTFA, mLDFA, and MPTA outliers in the MA-TKA group was significantly lower compared to the CM-TKA group (P<0.05). Knee varus deformity was properly corrected and the mechanical axis was restored in all patients, regardless of the treatment group. Only for varus corrections ≥ 10° did TTTA change significantly (p < 0.01) and ankle varus incongruence aggravate post-operation. The ΔTTTA correlated negatively with ΔTFA (r=-0.310,P = 0.001) and correlated positively with ΔTPIA (r = 0.490,P = 0.000). When the varus correction was ≥ 7.55°, the probability of ankle varus incongruence exacerbation increased 4.86-fold.ConclusionCompared with CM-TKA, MA-TKA osteotomy showed more precision but was unable to reduce post-operation ankle varus incongruence. When the varus correction ≥ 10°, ankle varus incongruence aggravated, while when the varus correction ≥ 7.55°, the probability of ankle varus incongruence increased 4.86-fold. This may occasion the pathogenesis of ankle pain following TKA.

The position of the lateral tibial spine and the implications for high tibial osteotomy planning

The lateral tibial spine (LTS) is frequently proposed as a correction target in high tibial osteotomy (HTO), although little is known about its exact radiographic position. This study primarily aims to define the position and variance of the LTS. Secondly, this study wants to investigate the relevance of the LTS position on the mechanical tibiofemoral angle (mTFA°) while planning and postoperatively landing the weight-bearing line (WBL) on this landmark. The LTS position was studied on preoperative full-leg standing radiographs (FLSR) and computed tomography (CT) scans in 70 cases. 3D models of the tibia were created in Mimics 23.0 and measurements were conducted in 3-matic 15.0 (Materialise, Leuven®). Next, 100 HTO cases were retrospectively planned with the WBL through the LTS according to Dugdale’s method on FLSR. Finally, 55 postoperative FLSR which had the WBL on the LTS (±2%) were assessed for mTFA° outcome. Statistics were conducted in GraphPad 8.0. The LTS was located at 58.3%±1.9 [55-63%] in 2D and 57.3%±2.2 [53-63%] in 3D showing a high correlation (r=0.77 [0.65 to 0.85]). The planned mTFA on the LTS was 181.8°±0.3 (181.3°-182.5°). On postoperative FLSR, the mTFA was 182.2°±0.6 (180.9°-183.1°). The lateral tibial spine is located at 57-58% on the tibial plateau with a 10% maximal variation range. Good agreement was found between 2D and 3D imaging modalities while evaluating its position in the coronal plane. When aiming the WBL through the LTS during valgus-producing HTO, a consistent realignment of 181-183° mTFA can be expected when performing accurate surgery.

The gap height in open wedge high tibial osteotomy is not affected by the starting point of the osteotomy

IntroductionIn open-wedge high-tibial-osteotomy (OWHTO), most surgeons use a preoperative planning software and realise that they should match the intraoperative alignment correction with the preoperative plan. We aimed to determine whether there is a difference in osteotomy gap height when starting the OWHTO either 3 or 4 cm distal to the joint line. This should help to clarify whether the osteotomy starting point must exactly match the preoperative planning.Methods25 patients with constitutional varus alignment were planned for OWHTO. Long-leg-standing-radiographs and mediCAD-software were used. Osteotomy was planned to a neutral Hip-Knee-Ankle angle (HKA) of 0°. The osteotomy-starting-point was either 3 or 4 cm distal to the medial joint line. The following angles were compared: mechanical medial proximal tibial angle (mMPTA), mechanical lateral distal femoral angle (mLDFA), joint line conversion angle (JCA), mechanical Tibio-Femoral angle (mTFA) or Hip Knee Ankle (HKA) angle.Results25 Patients (18 males, 7 females) had a mean age of 62 ± 16.6 years and showed a varus-aligned leg-axis. The HKA was − 5.96 ± 3.02° with a mMPTA of 82.22 ± 1.14°. After osteotomy-planning to a HKA of 0°, the mMPTA was 88.94 ± 3.01°. With a mean wedge height of 8.08 mm when locating the osteotomy 3 cm and a mean wedge height of 8.05 mm when locating the osteotomy 4 cm distal to the joint-line, there was no statistically significant difference (p = 0.7).ConclusionWhen performing an OWHTO aiming towards the tip of the fibula, the osteotomy starting point does not need to exactly match the planned starting-location of the osteotomy. A starting-point 1 cm more distal or proximal than previously determined through the digital planning does not alter the size of the osteotomy gap needed to produce the desired amount of correction.

In closed wedge distal femur osteotomies for correction of valgus malalignment overcorrection of mLDFA should be avoided.

The purpose of the study was to investigate the influence of the mLDFA (mechanical lateral distal femur angle) as a parameter in varus realignment osteotomies for valgus deformities of the knee. We hypothesized that joint line obliquity with mLDFA > 90° after distal femur osteotomy (DFO) is associated with inferior clinical outcome. In a retrospective study, a total of 52 patients with isolated femoral valgus deformities were included in the study. The mean postoperative follow-up was 70.5 (SD 33.3) months (standard deviation SD±33.3). In all patients, a distal femur osteotomy was performed. A clinical examination and survey of questionnaires was conducted with the HSS (Hospital for Special Surgery), LG (Lysholm-Gilquist), and KOOS (Knee Injury and Osteoarthritis Outcome Score) scores. Several radiological parameters were assessed on long-standing x-rays: mechanical tibio-femoral angle (mTFA), mLDFA, mechanical medial proximal tibia angle (mMPTA), joint-line convergence angle (JLCA). The ttest was used for normally distributed data. The Mann-Whitney U test was performed in non-normally distributed data. The mLDFA was 84.9° (SD±2.3) preop and changed to 91.9° (SD±3, 22.9) postop. The mTFA (mechanical tibio-femoral angle) was 5.2° (SD±2.9°) preop and -1.8° (SD±2.9) postop demonstrating a difference of 6.7°. For analysis, the data was divided into two groups based on postop mLDFA. Group 1: mLDFA ≤ 90°; Group 2: > 90°. Postoperatively, a mean mLDFA of 88.6° (SD±1.4°) was measured in group 1 and 93.9° (SD±2.1) in group 2. The change in mLDFA was 4.7° (SD±1.6) in group 1 and 8.4° (SD±2.8) in group 2. Preoperatively, the mTFA was 4.8° (SD±1.9) in group 1 and 5.5° (SD±3.3) in group 2. Postoperatively, the mTFA decreased in group 1 by 4.8° (SD±2.3) to -0.1° (SD±2.1). In group 2, the mTFA decreased by 8.2° (SD±3.8) to -2.8° (SD±2.9). Regarding the HSS, group 1 showed a 10.4 points better score than group 2 (p<0.01). Also, regarding the Lysholm, a significant difference of 16.9 points was found (p<0.01). Correction of valgus knees using closed wedge DFO leads to good clinical results. A postoperative mLDFA of 85-90° results in superior clinical outcome compared to mLDFA > 90°. Joint-line obliquity should be avoided using double level osteotomy, if needed. III.

Predicting Success of Deformity Correction With Tension Band Plating in Early-Onset Tibia Vara.

Angular deformity correction with tension band plating has not been as successful in early-onset tibia vara (EOTV) as it has been in other conditions. Our hypothesis is that perioperative factors can predict the success of lateral tibial tension band plating (LTTBP) in patients with EOTV. A retrospective review was performed at 7 centers evaluating radiographic outcomes of LTTBP in patients with EOTV (onset <7y of age). Single-event tibial LTTBP outcome was assessed through medial proximal tibial angle (MPTA). The final limb alignment following comprehensive limb growth modulation (CLGM), which could include multiple procedures, was assessed by mechanical axis zone (MAZone), mechanical tibio-femoral angle (mTFA), and mechanical axis deviation (MAD). Preoperative age, weight, deformity severity, medial physeal slope, and Langenskiöld classification +/- modification were investigated as predictors of outcome. Success was defined as the correction or overcorrection to normal age-adjusted alignment. The minimum follow-up was 2 years except when deformity correction, skeletal maturity, or additional surgery occurred. Fifty-two patients with 80 limbs underwent 115 tibial LTTBP procedures at a mean age of 5.3y, including 78 primary, 21 implant revisions, and 15 reimplantations for recurrence. Tibial LTTBP resulted in a mean change of +8.6 o in MPTA and corrected 53% of tibias. CLGM resulted in MAD correction for 54% of limbs.Univariate analysis showed that success was best predicted by preoperative age, weight, MPTA, and MAD. Multivariate analysis identified that preoperative-MPTA/MAD and preoperative-weight<70kg were predictive of MPTA and MAD correction, respectively. The probability of success tables are presented for reference. Successful correction of MPTA to age-adjusted norms following a single-event LTTBP occurred in 53% of tibias and was best predicted by preoperative-MPTA and preoperative body weight <70kg. Comprehensive growth modulation corrected limbs in 54%. The probability of correction to age-adjusted MAD is best estimated by preoperative-MAZone 1 or 2 (MAD ≤40mm). Limbs with preoperative-MAD>80mm improved, but ultimately all failed to correct completely with CLGM. Osteotomy may need to be considered with these severe deformities. While modified Langenskiöld classification and medial physeal slope have been shown to predict the outcome of osteotomy, they were not predictive for LTTBP. Change in MPTA was common after physeal untethering. Level-III.

Predicting Deformity Correction of Growth Modulation in Late-onset Tibia Vara.

Growth modulation in late-onset tibia vara (LOTV) has been reported to yield variable results. We hypothesized that parameters of deformity severity, skeletal maturity, and body weight could predict the odds of a successful outcome. A retrospective review of tension band growth modulation for LOTV (onset ≥8 y) was performed at 7 centers. Tibial/overall limb deformity and hip/knee physeal maturity were assessed on preoperative anteroposterior standing lower-extremity digital radiographs. Tibial deformity change with first-time lateral tibial tension band plating (first LTTBP) was assessed by medial proximal tibia angle (MPTA). Effects of a growth modulation series (GMS) on overall limb alignment were assessed by mechanical tibiofemoral angle (mTFA) and included changes from implant removal, revision, reimplantation, subsequent growth, and femoral procedures during the study period. The successful outcome was defined as radiographic resolution of varus deformity or valgus overcorrection. Patient demographics, characteristics, maturity, deformity, and implant selections were assessed as outcome predictors using multiple logistic regression. Fifty-four patients (76 limbs) had 84 LTTBP procedures and 29 femoral tension band procedures. For each 1-degree decrease in preoperative MPTA or 1-degree increase in preoperative mTFA the odds of their successful correction decreased by 26% in the first LTTBP and 6% by GMS, respectively, controlling for maturity. The change in odds of success for GMS assessed by mTFA was similar when controlling for weight. Closure of a proximal femoral physis decreased the odds of success for postoperative-MPTA by 91% with first LTTBP and for final-mTFA by 90% with GMS, controlling for preoperative deformity. Preoperative weight ≥100 kg decreased the odds of success for final-mTFA with GMS by 82%, controlling for preoperative mTFA. Age, sex, race/ethnicity, type of implant, and knee center peak value adjusted age (a method for bone age) were not predictive of outcome. Resolution of varus alignment in LOTV using first LTTBP and GMS, as quantified by MPTA and mTFA, respectively, is negatively impacted by deformity magnitude, hip physeal closure, and/or body weight ≥100 kg. The presented table, utilizing these variables, is helpful in the prediction of the outcome of the first LTTBP and GMS. Even if complete correction is not predicted, growth modulation may still be appropriate to reduce deformity in high-risk patients. Level III.

EFFECT OF HIGH TIBIAL OSTEOTOMY ON ANKLE AND SUBTALAR JOINT ALIGNMENT

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.

Functional gait analysis reveals insufficient hindfoot compensation for varus and valgus osteoarthritis of the knee

PurposeThe hindfoot is believed to compensate varus and valgus deformities of the knee by eversion and inversion movements. But these mechanisms were merely found in static radiologic measurements. The aim of this study was, therefore, to assess dynamic foot posture during gait using pressure-sensitive wireless insoles in patients with osteoarthritis of the knee and frontal knee deformities.MethodsPatients with osteoarthritis of the knee were prospectively included in this study. Patients were clinically and radiologically (mechanical tibiofemoral angle (mTFA), hindfoot alignment view angle (HAVA), and talar tilt (TT)) exa mined. Gait line analysis was conducted using pressure-sensitive digital shoe insoles.ResultsEighty-two patients (varus n = 52, valgus n = 30) were included in this prospective clinical study. Radiologically, the mTFA significantly correlated with the HAVA (cor = −0.72, p < 0.001) and with the TT (Pearson’s cor = 0.32, p < 0.006). Gait analysis revealed that the gait lines in varus knee osteoarthritis were lateralized, despite the hindfoot valgus. In valgus knee osteoarthritis, gait lines were medialized, although the hindfoot compensated by varization.ConclusionsFunctional dynamic gait analysis could demonstrate that the hindfoot is not able to sufficiently compensate for frontal malalignments of the knee joint, contrary to static radiologic findings. This led to a narrowing of the joint space of the ankle medially in varus and laterally in valgus knee osteoarthritis.