Varus Gonarthrosis Research Articles

O papel das microfraturas associadas a osteotomia tibial no tratamento da gonartrose com geno varo

ObjectiveTo evaluate the microfracture intervention with tibial valgus osteotomy associated in the treatment of varus gonarthrosis. MethodsFrom November 2005 to May 2013, 129 patients with medial gonarthrosis, varus deformity (8°‐12°), and range of movement greater than 90° were evaluated. Patients with advanced gonarthrosis (Alhbäck 3, 4, and 5), Outerbridge lesion inferior to IV, previous knee surgery, body mass index greater than 35kg/m2, and/or cruciate ligament injuries were not included. All patients were treated with videoarthroscopy followed by tibial valgus osteotomy. In the group osteotomy associated with microfracture (n = 56, mean age = 39.3), tibial valgus osteotomy and microfracture techniques to address chondral defects were used. In the isolated osteotomy group (n = 73, mean age = 41.4), only this procedure was performed. Post‐surgical follow‐up was 24 months, with four evaluations in the first six months, proceeding to biannual twice‐a‐year evaluation in the subsequent period. The Lysholm scale was used for functional monitoring. ResultsThere was a significant improvement in the pain, limping, and squatting domains of the Lysholm scale but only in the isolated osteotomy group. A greater variance of results was observed in the osteotomy group associated to microfracture, in addition to an increased risk of functional deterioration (OR = 8.64). ConclusionThe association of microfractures and tibial valgus osteotomy was correlated to lower functional outcomes than tibial valgus osteotomy alone, and may be related to the risk of worsening in the first two postoperative years.

A patellar tendon length conservation method: Biplanar retrotubercle open-wedge proximal tibial osteotomy.

OBJECTIVE:The early-period results of our technique for performing a medial biplanar retrotubercle open-wedge proximal tibial osteotomy for the surgical treatment of varus gonarthrosis were evaluated and compared with those reported in the literature.METHODS:The clinical and radiological results of a medial biplanar retrotubercle open-wedge proximal tibial osteotomy performed on 23 knees in 22 patients with medial gonarthrosis with varus alignment were analyzed.RESULTS:Twenty patients were female and 2 were male. At the time of surgery, the mean age was 56.22 years (44–66 years), the mean body mass index was 31.95 kg/m2 (23.4–44.9 kg/m2), and the mean Hospital for Special Surgery (HSS) score was 68.7 (48–83). The mean preoperative femorotibial anatomical axis angle was 186.39° (173–194°), and the mean Insall-Salvati index value was 1.04 (0.94–1.171). The mean length of follow-up was 30.19 months (6–42 months). At the last follow-up examination, the mean HSS score was 86.48 (74–100), the mean femorotibial anatomical axis angle was 175° (168–171°), and the mean Insall-Salvati index value was 1.06 (0.857–1.32). Comparison of the final follow-up values with the preoperative values demonstrated significant improvement in the HSS score and femorotibial anatomical axis angle, but no significant difference in the Insall-Salvati index value.CONCLUSION:The results of this study indicated that frontal and sagittal plane deformities in patients with varus gonarthrosis can be treated with biplanar retrotubercle open-wedge proximal tibial osteotomy with good clinical results that achieve patellar tendon length stability and avoid patellofemoral problems.

A novel technique in repair of radial meniscus tear

Introduction:Radial meniscus tears are seen in young patients, especially with anterior cruciate ligament ruptures. Repair of complet radial meniscus tear is necessary for the meniscus functions. The most important factor for success of the meniscus repair is primary stability, but it is still unknown which technique is ideal repair technique.Aim:We developed a new suture technique named Cross Horizontal Loop(CHL). In this novel technique the contact between meniscal tissue and suture is more than Horizontal Loop(HL) that routinely used today. So, we think that this technique will provide better fixation than HL. We aimed to compare 2 repair techniques (CHL vs. HL) using human lateral menisci biomechanically with cyclic loading and load to failure testsMaterials-Methods:We used 20 intact lateral meniscus obtained from patients that operated (total knee replacement) for varus gonarthrosis in our clinic. All menisci were cut radially. In the first group (n:10) menisci were repaired with standart horizontal loop technique, and in the second group (n:10) cross horizontal loop technique were used for repair. All specimens were tested with load to failure test after cyclic loading test (500 cyclus X 5-30 N).Results:Both groups have similar failure load (71,4±17,52 N vs. 77,9±28,49 N; p:0,559) and stiffness (24,46±19,19 N vs. 24,48±15,87 N; p:0,818). CHL group has less peak displacement (6,26±1,24 mm vs. 8,4±1,92 mm; p:0,010).Conclusions:This novel repair technique decreases the amount of displacement according to standard technique while as strong as standart technique routinely used. In this way; we believe that it will increase the rate of healing in clinical use.Tablo 1.Radial Yırtıkların Gruplara Göre Dağılımı Gruplar Değiskenler Horizontal CrossHorizontal Loopt/Zp nOrt±SSnOrt±SS Peak Displacement (mm)96,26±1,24118,4±l,922,880 0,010* Peak Force (N)935,82±1,471138,5±2,672,842 0,015* Static Peak Force (N)971,4±17,521177,9±28,490,5960,559*Stiffness (N/mm)624,46±19,19624,48±15,870,3200,818 p<0.05 anlamlılık düzeyidir. * Bağımsız Örneklem T Testi ** Mann Whitney U Testi Schematic drawing of the repair techniques

Posterior cruciate-retaining versus posterior-stabilized total knee arthroplasty for osteoarthritis with severe varus deformity

ObjectiveThe aim of this study was to compare the radiological and functional results of posterior cruciate ligament (PCL) – retaining and posterior-stabilized total knee arthroplasties in patients with severe varus gonarthrosis. MethodsMedical records of 112 knees of 96 patients who underwent total knee arthroplasty for severe varus (≥15°) were reviewed. PCL-retaining and PCL-stabilizing groups consisted of 58 and 54 knees, respectively. Mean follow-up time was 56.6 months (range: 24–112 months). Knee Society (KS) clinical rating system was used in clinical evaluation. Range of motion, degree of flexion contracture, postoperative alignment, and complication rates were compared between the groups. ResultsMean preoperative mechanical tibiofemoral angle was 20.1° in varus alignment, and was restored to 4.6° in valgus postoperatively. No statistically significant differences were found between PCL-stabilizing and PCL-retaining groups when KS knee scores, function scores, and flexion arc were evaluated. Two patients in PCL-retaining group underwent revision surgery due to aseptic loosening of tibial component. One patient in PCL-stabilizing group needed arthrotomy due to patellar clunk syndrome. ConclusionThere were no notable differences between the 2 groups and PCL-retaining design had outcomes as good as PCL-stabilizing total knee implant in osteoarthritic knees with severe varus deformity. Level of evidenceLevel III, Therapeutic study.

Medial Open Wedge Osteotomy Treatments in Varus Gonarthrosis and Long Term Results

Medial Open Wedge Osteotomy Treatments in Varus Gonarthrosis and Long Term Results

High tibial osteotomy in the ACL-deficient knee with medial compartment osteoarthritis

High tibial osteotomy (HTO) has traditionally been used to treat varus gonarthrosis in younger, active patients. Varus malalignment increases the risk of progression of medial compartment osteoarthritis and an HTO can be performed to realign the mechanical axis of the lower limb towards the lateral compartment, thereby decreasing contact pressures in the medial compartment. Anterior cruciate ligament (ACL) insufficiency may lead to post-traumatic arthritis due to altered joint loading and associated injuries to the menisci and articular cartilage. Understanding the importance of posterior tibial slope and its role in sagittal knee stability has led to the development of biplane osteotomies designed to flatten the posterior tibial slope in the ACL deficient knee. Altering the alignment in both the sagittal and coronal planes helps improve stability as well as alter the load in the medial compartment. Detailed history, physical exam and radiographic analysis guide treatment decisions in this high demand patient population. Lateral closing wedge (LCW) and medial opening wedge (MOW) HTOs have been performed and their potential advantages and disadvantages have been well described. Given the triangular shape of the proximal tibia, it is imperative that the surgeon pay close attention to the geometry of the osteotomy “gap” when performing MOW HTO to avoid inadvertently increasing the posterior tibial slope. Simultaneous ACL reconstruction may require technique modifications depending on the type of HTO and ACL graft chosen. With appropriate patient selection and good surgical technique, it is reasonable to expect patients to return to activities of daily living and recreational sports without debilitating pain or instability.

Effects of total knee arthroplasty on ankle alignment in patients with varus gonarthrosis: Do we sacrifice ankle to the knee?

Total knee arthroplasty is one of the most commonly preferred surgical methods in the treatment of patients with varus gonarthrosis. In this study, we aimed to evaluate the radiological changes observed in the ankles after total knee arthroplasty. Between May 2012 and June 2013, 80 knees of 78 patients with varus deformity over 10° underwent total knee arthroplasty. For each patient, full-leg standing radiographs were obtained pre- and post-operatively. Mechanical and anatomical axes (HKA and AA), lateral distal femoral angle, medial proximal tibial angle, lateral distal tibial angle (LDTA), ankle joint line orientation angle (AJOA), tibial plafond talus angle (PTA) and talar shift were measured for each patient both pre- and post-operatively. Pre-operatively, the mean HKA was 16.6° and the mean AA was 10.41°, both in favour of varus alignment. Post-operatively, the mean HKA decreased to 3.6° and the mean AA to -2.1. The mean LDTA was 87.3°. Before the operation, the mean AJOA was -7.6°, opening to the medial aspect of the ankle, and it was 0.04° after the operation and opening to the lateral aspect (p<0.05). Our study reveals the changes occurring in the ankle after acute correction of long-standing varus deformity of the knee using total knee arthroplasty. In cases undergoing knee arthroplasty, effect of the acute change in the alignment of the knee on the ankle should be taken into consideration and the amount of correction should be calculated carefully in order not to damage the alignment of the ankle. IV.

The influence of knee malalignment on the ankle alignment in varus and valgus gonarthrosis based on radiographic measurement

PurposeThe lower limb misalignment as calculated by radiography has an evident effect on the development and progression of knee osteoarthritis (OA). However, whether the knee malalignment has an influence on ankle alignment is unknown. The purpose of this study was to discuss the correlation between knee and ankle alignment in varus and valgus gonarthrosis. MethodsThis is a retrospective study of 149 patients with symptomatic varus and valgus knee OA who intend to take total knee arthroplasty (TKA) between January and October 2013. A protocol for the measurement of knee-ankle alignment and angles on full-length standing anteroposterior radiographs of the lower extremity was outlined in detail with step-by-step instructions. Two observers measured the angles chosen. The Pearson’s correlation tests were used for the statistical analysis. ResultsPearson’s correlation test results for unilateral varus or valgus gonarthrosis showed that the varus or valgus deformity of the knee can influence the tilt angle and tibiotalar angle of the ankle in operative side signficantly(p<0.05), and the tilt angle of the ankle can also be affected in nonoperative side (p<0.05). Moreover, the tilt angle of the bilateral ankle can be simultaneously affected in bilateral varus gonarthrosis (p<0.05). ConclusionThese findings suggest that the varus and valgus deformity of the knee can induce the tilt of the ankle and influence the ankle alignment, which may further accelerate the degeneration of the ankle. Moreover, the knee alignment in the nonoperative side can also result in the change of ankle alignment at the same time.

Regional differences in temperature course after knee arthroplasty.

During wound healing after surgery, physiological inflammation leads to an increase in soft tissue perfusion. This is reflected by a characteristic temperature course in the skin. Although local surgical trauma also influences soft tissue perfusion, no data have been available on the regional temperature distribution after knee arthroplasty to date. This study aims at testing the hypothesis that the greatest regional difference in the temperature course is on the site of the maximum surgical trauma (medially) after knee arthroplasty implantation. This is to our knowledge the first study to present regional differences in the temperature course after TKA which would limit the diagnostic value of thermography. Forty-two subjects who were to receive a surface replacement of the knee joint due to primary varus gonarthrosis were included in the study. In all cases, a medial parapatellar approach was chosen. Patients who underwent lateral release or a release of the lateral ligament structures were excluded. In all patients, a thermographic temperature determination was carried out on the operated knee joint every day up to the seventh post-operative day. On the medial side, there was no significant change in temperature between day one 34.9°±0.2° (34.6-35.3°C) and seven after surgery. Thereafter, the temperature remained constant here up to the seventh day after the operation. In contrast to this, on the lateral side there was an increase in skin temperature from the second 35.0±0.2°C (34.7-35.4°C) to the fifth 34.6°±0.2° (34.1-34.9°C) post-operative day (p=0.002). Thereafter, the temperature remained constant here up to the seventh day after the operation. This study refutes the hypothesis that the greatest regional difference in the temperature course is on the site of maximum surgical trauma (medially) after knee arthroplasty implantation. It is shown to the contrary that there is the least regional difference in the temperature course on the site of maximum surgical trauma (medially) after total knee arthroplasty implantation. It is on the site of the minimal trauma (laterally) where marked differences in the temperature course appeared. The normal temporary temperature increase typical of physiological wound healing could only be shown at a distance from the site of soft tissue preparation. This may be the result of a local compromise of perfusion. Consequently, the post-operative diagnostic application of thermography remains limited to regions distant from the surgical site. This may prevent misinterpretation of post-operative thermographic measurements for scientific or clinical reasons. II.

Proximal Tibia Medial Biplanar Retrotubercle Open Wedge Osteotomy for Varus Knees with Medial Gonarthrosis

Objectives:The purpose of this study is to evaluate the early results of proximal tibia medial biplanar retrotubercle open wedge osteotomy for varus gonarthrosis and compare the results with the literatüre.Methods:The results of proximal tibia medial biplanar retrotubercle open wedge osteotomy for 23 knees of 22 patients with medial gonarthrosis were evaluated clinically and radiologically.Results:Twenty of the patients were female and two were male. Mean age of the patients was 56.24; mean boy mass index was 31.95 and preoperative HSS (Hospital for Special Surgery) score was 68.7. Mean tibiofemoral axis was 186.39° and mean Insall-Salvatti index value was 1.04 preoperatively. Mean follow up period was 30.19 months. Mean HSS score was 86.48, femorotibial anatomic axis angle was 175° and Insall-Salvati index value 1.06 during the last follow-up. The improvement of the HSS score and the femorotibial anatomic axis angle was statistically significant. However, the change in Insall Salvati index values was statistically insignificant. Nonfatal pulmonary embolus in 1 patient, and deep vein thrombosis that occured one year after the procedure in 1 patient, rhabdomyolysis in 1 patient and loss of correction (relapse) in 1 patient were encountered as complications.Conclusion:Our results show that proximal tibia medial biplanar retrotubercle open wedge osteotomy improves the frontal and sagittal plane deformities without changing the patellar tendon length. Hence, possible patellofemoral problems are prevented and the clinical results are improved.

How safe are orthoroentgenograms in determining the amount of correction for varus deformities?

In this study, we evaluated the effects of the distance of the legs from the midline on alignment and angles of the lower extremities in orthoroentgenograms. Between March 2012 and April 2013, 95 limbs of 56 patients with varus deformity who underwent orthoroentgenogram to identify the amount of joint laxity in two positions were included in this study. The initial X-ray was performed with the feet in contact, while the other was performed as the legs were abducted to be in line with the shoulders. For each orthoroentgenogram, the mean mechanical axis angle, anatomical axis, and joint line orientation angles were measured retrospectively. These measurements were repeated for 43 limbs with varus deformity >10°. In the orthoroentgenograms with the feet in contact, the mean mechanical axis angle was 9.58°±5.7°, (0.20°; 26.0°), the mean anatomical axis angle 3.65°±6.14°, (-9.0°; 21.0°), and the mean joint line orientation angle -3.41°±2.52°, (-12.0°; 1.60°). In the orthoroentgenograms with the legs abducted, the mean mechanical axis angle was 7.73°±5.58°, (-3.0°; 23.0°), the mean anatomical axis angle 2.62°±5.87°, (-11.0°; 18.30°), and mean joint line orientation angle was -2.44°±2.41°, (-13.0°; 3.0°). The differences in the angles between the two positions were statistically significant (p<0.005). Our study results showed that the mean values of mechanical axis angle, anatomical axis and the joint line orientation angle were higher in orthoroentgenograms with the feet in contact than the orthoroentgenograms with the legs abducted in patients with varus gonarthrosis. We suggest that this may lead to mistakes in the preoperative planning. Ideal positions should be standardized to minimize possible problems.

Multi-modal physiotherapy and high tibial osteotomy can mitigate risk factors for disease progression in patients with varus gonarthrosis

Multi-modal physiotherapy and high tibial osteotomy can mitigate risk factors for disease progression in patients with varus gonarthrosis

Le osteotomie tibiali di addizione nelle gonartrosi e nelle deformità post-traumatiche in valgo: indicazioni, tecnica chirurgica, complicanze, risultati

The effectiveness of tibial osteotomy for the treatment of varus gonarthrosis has been widely discussed in the literature, while works reporting its role in the correction of constitutional or acquired post-traumatic valgus deformities are less numerous, if not rare. We present the study of 16 patients with valgus knee treated by external opening wedge tibial varus osteotomy above the tibial tuberosity between 1998 and 2008. We analyzed the results with a median follow-up of 6 years (range 2–12 years): with the rating scale of Lysholm and Gillquist, the average value was 83 (range 61–93). Our indication for surgical intervention was addressed to subjects aged <60–62 years with unadvanced valgus gonarthrosis, <12°, with medial-lateral laxity, mostly occurring after lateral spontaneous or surgical meniscectomy, outcomes of tibial lateral plateau fracture or constitutional valgus deformities. Under such conditions, this procedure, that is performed in intraligamental area, can restore ligament tension and rebalance the knee, at the cost of an acceptable joint line’s obliquity.

Combined Tibial Tubercle Osteotomy With Medial Opening Wedge High Tibial Osteotomy Minimizes Changes in Patellar Height

Background: Medial opening wedge high tibial osteotomy (HTO) for the treatment of varus gonarthrosis can be associated with inadvertent decreases in patellar height. Hypothesis: Decreases in patellar height observed after medial opening wedge HTO can be minimized with the addition of a tibial tubercle osteotomy (TTO). Study Design: Cohort study; Level of evidence, 3. Methods: Twenty-nine patients undergoing medial opening wedge HTO with a concurrent TTO were matched with 29 controls who previously underwent medial opening wedge HTO without a TTO. Both groups had substantial varus malalignment (mean mechanical axis angle, −10° ± 3°) requiring large corrections. Measurements of patellar height and posterior tibial slope were calculated from standing lateral radiographs and compared preoperatively and 6 months postoperatively. Patellar height measures included the Blackburne-Peel index, Caton-Deschamps index, Miura-Kawamura index, Insall-Salvati ratio, and modified Insall-Salvati ratio. Results: The changes in the Blackburne-Peel, Caton-Deschamps, and Miura-Kawamura indices were significantly less in the HTO/TTO group versus the HTO group. There were 3 of 29 (10%) new cases that met the radiographic criteria for patella infera in the HTO/TTO group versus 11 of 29 (38%) new cases of patella infera found postoperatively in the HTO group, suggesting an absolute risk reduction of 28% with TTO. The changes in the Blackburne-Peel and Caton-Deschamps indices were correlated to a larger preoperative varus deformity in the coronal plane (r = 0.52 and r = 0.41, respectively). Conclusion: The addition of a TTO when performing a medial opening wedge HTO minimizes the decreases in patellar height associated with the procedure.

Boomerang proximal tibial osteotomy for the treatment of severe varus gonarthrosis

Dear Editor, We read with interest the recent article by C. Sangkaew et al. [1], describing the role of boomerang osteotomy for the treatment of severe varus gonarthrosis. There are a large number of research publications clearly indicating that, “HTO is to buy time until future TKR is planned in a properly selected patient”. But here the authors have given a good result in grade IV & V gonarthrosis with severe varus deformity. However, we have a few queries which we would like to communicate with the author: The authors postulate that results of osteotomy would not depend on the number of compartments involved or associated angular deformity, but most authors consider HTO as a procedure for uni-compartmental involvement [2]. Flexion contracture is common in grade IV & V gonarthrosis with severe varus deformity due to shortening of the postero-medial structures including capsule, medial collateral ligament (MCL) and posterior cruciate ligament (PCL). Flexion contracture (FC) cannot be corrected without releasing these structures. But the authors have shown a decrease in FC in 30 of 42 patients (P < 0.001). Grade IV & V gonarthrosis is associated with a large number of osteophytes on the medial side of femur and tibia along with contracted MCL. Thus, it is really difficult to displace the proximal fragment laterally without removing the osteophytes and soft tissue release as shown in figure 1 of the article [3]. Severe gonarthrosis with bone loss on both medial and lateral sides with lateral subluxation of tibia as shown in a photograph in the article, if treated with osteotomy, will definitely exhibit a ‘teeter-totter’ effect, and most probably will remain in varus after HTO. The teeter-totter effect, where simultaneous contact of medial and lateral tibio-femoral compartment is not possible and it will remain unstable [4]. The author has done very well in taking considerations of pathophysiological origin of pain in varus gonarthrosis and relieving of pain by realignment [5], but mere correction of alignment will not relieve the pain, as all three compartments are diseased and unstable.

Reply to letter to the editor on: Boomerang proximal tibial osteotomy for the treatment of severe varus gonarthrosis

Reply to letter to the editor on: Boomerang proximal tibial osteotomy for the treatment of severe varus gonarthrosis

Staged medial opening wedge high tibial osteotomy for bilateral varus gonarthrosis: biomechanical and clinical outcomes

(1) To evaluate the effect of staged bilateral medial opening wedge high tibial osteotomy (HTO) on established biomechanical risk factors for disease progression and on validated measures of pain and function and (2) To compare outcomes in patients having the second surgery staged within or beyond 12 months of the first surgery. Thirty-seven patients with bilateral varus alignment and medial compartment osteoarthritis underwent staged bilateral medial opening wedge HTO (21 within and 16 beyond 12 months). Patients underwent full-limb standing anteroposterior radiographs to determine frontal plane alignment (mechanical axis angle) and three-dimensional gait analysis to estimate the distribution of load across the tibiofemoral compartments (external knee adduction moment). Patients also completed the Knee Injury and Osteoarthritis Outcomes Scores (KOOS), the Lower Extremity Functional Scale, the Short Form Health Survey and the six-minute walk test (6MWT). Patients (both limbs) were evaluated before and approximately 6, 12 and 24 months after each surgery. There were statistically and clinically significant changes in both limbs that were of similar magnitudes and that remained relatively stable over time postoperatively. Mean (95% CI) improvements in outcomes were as follows. Mechanical axis angle: 9.4° (8.4°, 10.4°) (i.e. average change of both limbs), peak knee adduction moment: -1.7%BW*Ht (-2.1, -1.4 %BW*Ht) (i.e. average change of both limbs), 6MWT: 36.7 m (19.4, 54.0 m), SF-12 Physical Component Summary: 12.0 (8.5, 15.5) and KOOS Pain: 25.4 (19.6, 31.2). Other than the shorter time period to reach maximum benefit of both surgeries, there were no remarkable differences at final assessment between patients having surgeries staged within or beyond 12 months. The present findings demonstrate that patients with bilateral varus gonarthrosis experience marked improvements in established biomechanical risk factors for disease progression bilaterally (mechanical axis angles and external knee adduction moments), as well as clinically important improvements in patient-important outcomes, after staged medial opening wedge HTO. Current findings suggest no difference in outcomes for patients who have the second surgery staged within or beyond 12 months of the first surgery. IV.

Arthroscopic and Computer-Assisted High Tibial Osteotomy Using Standard Total Knee Arthroplasty Navigation Software

Opening-wedge high tibial osteotomy is an increasingly performed procedure for treatment of varus gonarthrosis and correction of malalignment during meniscal transplantation or cartilage restoration. Precise preoperative planning and meticulous surgical technique are required to achieve an appropriate mechanical axis correction. We describe our technique of arthroscopic and computer-assisted high tibial osteotomy using commonly available total knee arthroplasty navigation software as an intraoperative goniometer. We believe that our technique, by providing intraoperative real-time guidance of the degree of correction that is accurate and reliable, represents a useful tool for the surgeon who uncommonly performs high tibial osteotomy.

Neutralizing high and low knee moments through surgical realignment

Purpose: To elucidate the effects of frontal plane lower limb alignment on gait biomechanics, we compared knee joint moments and frontal plane angular impulse before and after varus or valgus producing osteotomy in patients with lateral or medial compartment osteoarthritis, and in healthy participants with neutral alignment. Methods: Thirty-nine subjects participated (13 valgus gonarthrosis, 13 varus gonarthrosis, 13 controls). Patients underwent 3D gait analysis and radiographic assessment of alignment (mechanical axis angle; MAA) before and 6 months after surgery, and were compared to controls. Moments in each of the three orthogonal planes of movement were determined throughout stance phase and averaged over five trials of the same limb (operative limb, or limb closest to neutral for controls) while normalizing to body weight and height (%BW·Ht). Knee moments in all three planes were normalized to 100% of stance and peak values in the first and second halves of stance were identified. The frontal plane knee moment waveform was then integrated with respect to time to calculate the frontal plane knee angular impulse (%BW·Ht·s). Results: An ensemble average for the frontal plane knee moment before and after surgery with 95% confidence interval (CI) bars is illustrated in Figure 1. Mean changes (95%CI) in frontal plane angular impulse indicated a 0.82%BW·Ht·s (0.49,1.14) increase in adduction impulse in patients after varus osteotomy, and a 0.61%BW·Ht·s (0.37,0.86) decrease in adduction impulse in patients after valgus osteotomy, equating to a 53% and 45% change from preoperative values, respectively. Preoperative frontal plane angular impulse was significantly different between both patient groups and controls before surgery, but not after. There were less substantial findings in sagittal and transverse plane moment peaks. When compared to controls, the peak knee extension moment was significantly lower for both patient groups after surgery (p=0.008). The association between the changes in lower limb alignment and frontal plane knee angular impulse are plotted in Figure 2 (R=0.88, n=26). Conclusions: The cross-sectional data suggest that frontal plane angular impulse is very highly correlated to MAA before surgery (R=0.87), but not after (R=0.39), and that an adduction impulse predominates until 7º of valgus, at which point an abduction impulse predominates. The prospective surgical realignment data indicate that for every 1º change in MAA toward varus, there is a 0.1%BW·Ht·s (or 1.6N·m·s) change in frontal plane knee angular impulse toward adduction, and vice versa (Figure 2). These overall findings illustrate the potent effects that lower limb alignment can have on gait biomechanics. $$grap ic_94AB0E34-8D38-4F8A-AE45-E659B861CC5A$$ $$grap ic_AC2006D2-0EC3-4301-889F-EBA8CB318D37$$ Figure 2Scatter plot with mean regression line and 95% confidence interval.View Large Image Figure ViewerDownload Hi-res image Download (PPT)

Changes in valgus and varus alignment neutralize aberrant frontal plane knee moments in patients with unicompartmental knee osteoarthritis

To elucidate the effects of frontal plane lower limb alignment on gait biomechanics, we compared knee joint moments and frontal plane angular impulse before and after varus or valgus producing osteotomy in patients with lateral or medial compartment osteoarthritis, and in healthy participants with neutral alignment. Thirty-nine subjects participated (13 valgus gonarthrosis, 13 varus gonarthrosis, 13 controls). Patients underwent 3D gait analysis and radiographic assessment of alignment (mechanical axis angle; MAA) before and 6 months after surgery, and were compared to controls. Mean changes (95%CI) in frontal plane angular impulse indicated a 0.82%BW·Ht·s (0.49,1.14) increase in adduction impulse in patients after varus osteotomy, and a 0.61%BW·Ht·s (0.37,0.86) decrease in adduction impulse in patients after valgus osteotomy, equating to a 53% and 45% change from preoperative values, respectively. Preoperative frontal plane angular impulse was significantly different between both patient groups and controls before surgery, but not after. The cross-sectional data suggest that frontal plane angular impulse is very highly correlated to MAA before surgery (R=0.87), but not after (R=0.39), and that an adduction impulse predominates until 7° of valgus, at which point an abduction impulse predominates. The prospective surgical realignment data indicate that for every 1° change in MAA toward varus, there is a 0.1%BW·Ht·s (or 1.6Nms) change in frontal plane knee angular impulse toward adduction, and vice versa. These overall findings illustrate the potent effects that lower limb alignment can have on frontal plane gait biomechanics.