Differences between opening versus closing high tibial osteotomy on clinical outcomes and gait analysis

BackgroundHigh tibial osteotomy (HTO) for medial knee osteoarthritis (OA) is mainly performed via two procedures: closing wedge HTO (CW) and opening wedge HTO (OW). In this study, differences between these procedures were assessed by serial clinical evaluation and gait analysis before and after surgery.MethodsTwenty-one patients underwent HTO for medial knee OA in 2011 and 2012, with 12 patients undergoing CW and nine undergoing OW. The severity of OA was classified according to the Kellgren–Lawrence classification. The Japanese Orthopedic Association score for assessment of knee OA (JOA score), the Numeric Rating Scale (NRS), and the femoral tibial angle (FTA) on X-ray were evaluated. For gait analysis, gait speed, varus moment, varus angle and lateral thrust were calculated.ResultsThe JOA score and NRS were improved significantly one year postoperatively in both groups. The FTA was maintained in both groups at one year. Varus angle and varus moment were significantly improved in both groups at each postoperative follow-up, when compared preoperatively. Lateral thrust was significantly improved at three months postoperatively in both groups. However, the significant improvement in lateral thrust had disappeared in the CW group six months postoperatively, whereas it was maintained for at least one year in the OW group.ConclusionsThis study found that clinical outcomes were well maintained after HTO. OW reduced knee varus moment and lateral thrust, whereas CW had little effect on reducing lateral thrust.Level of evidenceLevel IV     

Dynamic foot function changes following total knee replacement surgery

BackgroundIndividuals with knee osteoarthritis (OA) have flatter/more pronated feet than those without OA, but it is unclear whether altered foot posture and function are a cause or consequence of knee OA. The purpose of this study was to examine whether changes in foot posture and function occur after realignment of the knee following total knee replacement (TKR).Materials and methodsNineteen patients with predominantly medial compartment knee OA were tested prior to and 12 months after TKR. The Foot Posture Index (FPI) and Arch Index (AI) were measured as well as motion of the tibia, rearfoot and forefoot using a 3D motion analysis system incorporating a multisegment foot model.ResultsThere were no significant changes in FPI or AI following TKR, however gait analysis revealed significant increases in tibial external rotation (? 18.7 ± 7.0° vs ? 22.5 ± 8.7°, p = 0.002), tibial transverse plane range of motion (? 9.1 ± 4.6° vs ? 11.4 ± 6.1°, p = 0.0028) and rearfoot range of motion in the frontal plane (8.6 ± 2.6° vs 10.4 ± 2.7°, p = 0.002), and a decrease in rearfoot transverse plane range of motion (8.7 ± 5.3° vs 5.9 ± 4.1°, p = 0.038) following the procedure.ConclusionsTKR produces no change in static foot posture, but results in significant changes in rearfoot kinematics during gait. These findings suggest that rearfoot motion compensates for changes in the alignment of the knee, highlighting the ability of the foot to accommodate for proximal skeletal malalignment.     

Quadriceps strength is not related to gait impact loading in knee osteoarthritis

Joint loading has been implicated in the pathogenesis of knee osteoarthritis (OA). While compartment-specific measures such as the knee adduction moment have received much attention in the literature, less is known about other measures of dynamic loading in this patient population. This cross-sectional study assessed strength and walking patterns of 204 individuals with radiographically confirmed medial tibiofemoral OA and varus malalignment. Pearson product moment correlations and regression analyses were used to determine the bivariate and multivariate relationships amongst measures of impact loading (rate of loading and heelstrike transient occurrence) with demographic, clinical (in particular, radiographic disease severity, lower limb alignment, and self-reported pain and function), and biomechanical variables (maximum voluntary isometric quadriceps strength and gait kinematics). While maximum voluntary isometric quadriceps strength was significantly correlated with rate of loading (r > 0.27) when walking at a freely chosen speed, multiple regression analyses indicated that rate of loading was primarily dictated by walking speed (p < 0.001), and the effect of quadriceps strength was insignificant when accounting for all other included variables. Individuals who exhibited a heelstrike transient in their vertical ground reaction force profile were significantly more varus malaligned and were more likely to demonstrate severe radiographic degeneration than those who did not exhibit heelstrike transients. These results demonstrate higher impact loading during walking in those with knee OA with faster self-selected walking speeds, though the relationship with quadriceps strength is less clear. Importantly a potential association between disease characteristics, such as malalignment and disease severity, and higher impact loading was also observed.     

Biomechanical effectiveness of a distraction–rotation knee brace in medial knee osteoarthritis: Preliminary results

BackgroundNon-pharmacological therapies are recommended for the care of knee osteoarthritis patients. Unloader knee braces provide an interesting functional approach, which aims to modulate mechanical stress on the symptomatic joint compartment. We aimed to confirm the biomechanical effects and evaluate functional benefits of a new knee brace that combines a valgus effect with knee and tibial external rotation during gait in medial osteoarthritis patients.MethodsTwenty patients with unilateral symptomatic medial knee osteoarthritis were included and they performed two test sessions of 3D gait analysis with and without the brace at the initial evaluation (W0) and after 5 weeks (W5) of wearing the brace. VAS-pain, satisfaction scores, WOMAC scores, spatio-temporal gait parameters (gait speed, stride length, stance and double stance phases, step width), and biomechanical data of the ipsilateral lower limb (hip, knee, ankle and foot progression angles) were recorded at each session.ResultsVAS-pain and WOMAC significantly decreased at W5. Walking speed was not significantly modified by knee bracing at W0, but increased significantly at W5. Knee adduction moments and foot progression angles significantly decreased in the terminal stance and push off, respectively, with bracing at W0 and W5. Lower-limb joint angles, moments and powers were significantly modified by wearing the brace at W0 and W5.ConclusionThis new knee brace with distraction–rotation effects significantly alters knee adduction moments and foot progression angles during gait, which might lead to significant functional gait improvements and have carry-over effects on pain at the short term in osteoarthritis patients (< 2 months).Level of Evidence: level IV.     

The knee adduction angle of the osteo-arthritic knee: A comparison of 3D supine,static and dynamic alignment

BackgroundEnd-stage knee osteoarthritis (OA) commonly results in knee arthroplasty. Three dimensional (3D) supine imaging is often used for pre-operative planning to optimise post-operative knee adduction angles (KAA). However, supine imaging may not represent loaded knee alignment. The aim of this study was to investigate differences in knee alignment under supine, static and dynamic conditions in healthy subjects and subjects with knee OA.MethodsNine healthy subjects and 15 subjects with end-stage knee OA were recruited. All subjects underwent supine imaging and motion capture during gait. KAAs were calculated from supine images (SUPINE), upright standing (STATIC) and at the first peak ground reaction force during gait (DYNAMIC), and were compared.ResultsKAAs were significantly higher (more varus) during gait compared with static (loaded and unloaded) in healthy subjects (p < 0.01) but not in subjects with knee OA. There was a good correlation between SUPINE and DYNAMIC for both healthy and OA subjects (R² > 0.58), with differences in the two relationships; healthy knees had a higher KAA during gait for any given KAA in the supine position, whereas OA knees that were valgus in imaging became more valgus during gait, and the opposite occurred for varus knees.ConclusionsFactors that may contribute to the noted differences between healthy and OA subjects include morphological changes in the joint as a result of OA, and gait compensation strategies in people with end-stage OA. Dynamic 3D motion capture provides important information about functional alignment that is not provided by supine imaging or static motion capture.Clinical RelevanceGait analysis may provide useful information to the surgeon during surgical planning of knee arthroplasties.     

A reduction in the knee adduction moment with medial thrust gait is associated with a medial shift in center of plantar pressure

The knee adduction moment (KAM) is an established marker of compartmental load distribution across the tibiofemoral joint. Research suggests a link between the magnitude of the KAM and center of plantar pressure (COP) thus alterations in the two may be related. The objective of this study was to investigate whether the COP predictably shifts when the KAM is reduced through a gait adaptation. Twenty healthy adults underwent gait analysis walking with their normal gait pattern and with medial thrust gait, a gait adaptation known to significantly reduce the KAM. Simultaneous COP and 3-D kinetics were acquired to allow for a comparison of the change in COP to the change in the KAM. The COP was quantified by determining a customized medial-lateral pressure index (MLPI) which compares the COP tracing line during the first and second halves of stance to the longitudinal axis of the foot. Linear regressions assessing the association between the changes in KAM and MLPI indicated that 48.3% (p = 0.001) of the variation in MLPI during the first half of stance can be explained by the KAM during the same period. A trend was observed between the association between the KAM and MLPI during the second half of stance (R² = 0.16, p = 0.080). Backwards elimination regression analysis was used to explore whether simultaneous consideration of the KAM and other potential confounding factors such as sagittal plane knee moments and speed explained variance in the MLPI during the first half of stance. Only the KAM exhibited explanatory power (β = 0.695, p = 0.001). During medial thrust gait, a reduction in the KAM was associated with a medial shift in the MLPI, and an increase in the KAM was associated with a lateral shift in the MLPI, especially in the first half of the stance phase. Together, these results demonstrate an inherent link between foot pressure and the KAM during medial thrust gait, and suggest that manipulating foot pressure may be a biomechanical mechanism for an intervention designed to improve loading conditions at the knee.     

Altered dynamic foot kinematics in people with medial knee osteoarthritis during walking: A cross-sectional study

BackgroundFootwear and insoles are used to reduce knee load in people with medial knee osteoarthritis (OA), despite a limited understanding of foot function in this group. The aim of this study was to investigate the differences in foot kinematics between adults with and without medial knee OA during barefoot walking.MethodsFoot kinematics were measured during walking in 30 adults; 15 with medial knee OA (mean age was 67.0 with a standard deviation (SD) of 8.9 years; height was 1.66 with SD of 0.13 m; body mass was 84.2 with SD of 15.8 kg; BMI was 30.7 with SD of 6.2 kg/m²; K–L grade 3: 5, grade 4: 10) and 15 aged and gender matched control participants with 12 motion analysis cameras using the IOR multi-segment foot model. Motion of the knee joint, hindfoot, midfoot, forefoot and hallux were compared between groups using clustered linear regression.ResultsThe knee OA group displayed reduced coronal plane range of motion of the midfoot (mean 3.8° vs. 5.4°, effect size = 1.1, p = 0.023), indicating reduced midfoot mobility. There was also a reduced sagittal plane range of motion at the hallux in the knee OA group compared to the control group (mean 29.6° vs. 36.3°, effect size = 1.2, p = 0.008). No statistically significant differences in hindfoot or forefoot motion were observed.ConclusionsPeople with medial knee OA display altered foot function compared to healthy controls. As foot and knee function are related, it is possible that altered foot function in people with knee OA may influence the effects of footwear and insoles.     

The influence of knee joint geometry and alignment on the tibiofemoral load distribution: A computational study

BackgroundDeviations in knee joint geometry and alignment were previously related to an increased risk for knee OA. These were hypothesized to influence the load distribution over the articular cartilage. Therefore, this study evaluated the effect of altered knee joint geometry and alignment in the coronal and transverse plane on the medial–lateral load distribution and ligament strain using a musculoskeletal modeling approach.MethodsJoint kinematics during gait were measured in 15 healthy adults. Using different musculoskeletal models with altered geometry of the tibia plateau or knee joint malalignment in the coronal and transverse plane, the resulting muscle, ligament and contact forces were calculated. Next, the distribution of the load over the medial and lateral condyle was analyzed and compared to the reference loading distribution, with neutral geometry and alignment, using repeated-measures ANOVA and individual t-tests, with a Bonferroni-corrected alpha level.ResultsCoronal plane malalignment significantly affected the load distribution. Small changes in coronal tibial slope had less pronounced effects on the load distribution, but increased ligament strains. Transverse plane malalignment only minimally affected the load distribution.ConclusionCoronal plane knee malalignment affected knee loading, with increased varus alignment resulting in increased medial loading. This confirms a causal relation between coronal malalignment and increased medial compartment loading and suggests a potential role of aberrant coronal plane alignment on OA initiation. Altered coronal tibial slope induced increased ligament strains, potentially contributing to a cascade of knee laxity and subsequently more extreme knee malalignment.     

Factors contributing to inherent varus alignment of lower limb in normal Asian adults: Role of tibial plateau inclination

PurposeThis prospective study aimed to evaluate radiographically, mechanical or hip–knee–ankle (HKA) axis in healthy, asymptomatic, Asian (Indian and Korean) adults between 20 and 40 years of age to determine the incidence of inherent varus (mechanical limb alignment of > 3° varus) and the factors influencing it.MethodsThree hundred and eighty-eight lower limbs were evaluated using full length, standing hip-to-ankle radiographs in 198 healthy, asymptomatic, Asian (Indian and Korean) adults between 20 and 40 years of age to assess the hip–knee–ankle (HKA) angle, medial proximal tibial angle (MPTA), femoral bowing and femoral neck–shaft angle to determine the incidence of inherent varus (mechanical limb alignment of > 3° varus) and the factors influencing it.ResultsOverall, the mean HKA angle was 177.6° ± 2.6° with 34.5% of limbs in inherent varus (mean HKA angle 174.9° ± 1.8°). The incidence of inherent varus was significantly higher (p = 0.01) in males (40%) compared to females (28%) but similar among Indian (34%) and Korean subjects (35%). The hip–knee–ankle (HKA) angle showed significant positive correlation (r = 0.82, p < 0.001) with only the medial proximal tibial angle (MPTA).ConclusionsInherent varus alignment of the lower limb is fairly common among asymptomatic, Asian adults. These results raise several pertinent questions regarding the role of inherent varus in the aetiopathogenesis of knee osteoarthritis and in lower limb realignment procedures.     

Dynamic alignment and its association with knee adduction moment in medial knee osteoarthritis

Lower limb dynamic alignment represents the limb position during functional loading conditions and obtains valuable information throughout the gait cycle rather than a single instant in time. This study aims to determine whether dynamic alignment is altered in medial knee osteoarthritis (OA) and how dynamic alignment is related to knee adduction moment (KAM). Community-dwelling women (n = 17) with medial OA in at least one knee, according to the American College of Rheumatology criteria and 17 body mass index-matched women without OA were recruited. A three-dimensional motion analysis system was used to collect the gait data at self-selected habitual and maximal speeds. Clinical evaluation of lower extremities, physical function, pain, habitual level of physical activity, quality of life and physical self-efficacy were assessed. Shank adduction angle and shank mean angular velocity were significantly greater in the OA group compared to the controls from heel strike to 30% stance. KAM was not different between the groups (p = 0.542). Dynamic alignment variables were the best predictors of KAM. Health-related quality of life, habitual level of physical activity, lower extremity muscle strength and balance performance were impaired in the OA group compared to the controls. The importance of variables that contribute to dynamic alignment and the contribution of limb alignment to KAM were highlighted in this study. Detection of postural changes such as altered dynamic alignment in early stages of OA will lead to the institution of joint-protective measures including changes in footwear, orthotics, gait re-training, use of assistive devices to reduce weight-bearing loads, strengthening and balance enhancing exercises, better analgesia, or cartilage-preserving pharmacotherapy.     

Aligning the tibial component with medial border of the tibial tubercle—is it always right?

IntroductionCorrect rotational alignment of the tibial component is crucial for total knee arthroplasty (TKA). Several studies have indicated that the best rotational orientation of the tibial component is close to the medial border of the tibial tubercle. However, it remains obscure whether it is always right. Thus, the objective of current study was to quantify tibial rotational alignment in 120 primary rotating platform TKAs using the medial border of tibial tubercle as a landmark between July 2008 and June 2010.MethodsThe femoral component was positioned parallel to the transepicondlylar axis, and a rotating platform trial insert was used to determine tibial insert rotational alignment relative to the most medial aspect of the tibial tubercle with the knee in full extension. Rotational alignment of the components was detected based on radiograph and CT scan. This investigation is based on the premise that all neutral points would lie within 10° of the mean.ResultsThe mean divergence external to the medial border of the tubercle was 2.3° ± 3.5°. However, six of the knees (5%) had neutral points ≥ 10° from the mean, including two valgus knees measured 10° of internal rotation and four varus knees measured 10° of external rotation.ConclusionUsing the medial border of tibial tubercle as a landmark does not always result in a good femoro-tibial rotational alignment. Surgeons using fixed bearings component should be aware of this effect to avoid suboptimal outcomes resulting from tibiofemoral rotational malalignment in full extension.Level of evidenceDiagnostic study, Level II-3.     

Acute influence of restricted ankle dorsiflexion angle on knee joint mechanics during gait

BackgroundRestrictions in range of ankle dorsiflexion (DF) motion can persist following ankle injuries. Ankle DF is necessary during terminal stance of gait, and its restricted range may affect knee joint kinematics and kinetics. The purpose of this study was to investigate the acute influence of varied levels of restricted ankle DF on knee joint sagittal and frontal plane kinematics and kinetics during gait.MethodsThirty healthy volunteers walked with a custom-designed ankle brace that restricted ankle DF. Kinematics and kinetics were collected using a 7-camera motion analysis system and two force plates. Ankle dorsiflexion was restricted in 10-degree increments, allowing for four conditions: Free, light (LR), moderate (MR) and severe restriction (SR). Knee angles and moments were measured during terminal stance.ResultsReal peak ankle DF for Free, LR, MR, and SR were 13.7 ± 4.8°, 11.6 ± 5.0°, 7.5 ± 5.3°, and 4.2 ± 7.2°, respectively. Peak knee extension angles under the same conditions were − 6.7 ± 6.7°, − 5.4 ± 6.4°, − 2.5 ± 7.5°, and 0.6 ± 7.8°, respectively, and the peak knee varus moment was 0.48 ± 0.17 Nm/kg, 0.47 ± 0.17 Nm/kg, 0.53 ± 0.20 Nm/kg, and 0.57 ± 0.20 Nm/kg. The knee varus moment was significantly increased from MR condition with an 8-degree restriction in ankle DF.ConclusionKnee joint kinematics and kinetics in the sagittal and frontal planes were affected by reduced ankle DF during terminal stance of gait. Differences were observed with restriction in ankle DF range of approximately 8°.Level of evidencelevel III     

Component rotational alignment in unexplained painful primary total knee arthroplasty

BackgroundRotational malalignment of the components in total knee arthroplasty (TKA) can be a factor in poor outcomes but has yet to be defined. This study compares the rotational alignment of components in a cohort of 56 patients with unexplained pain following total knee arthroplasty with a matched control cohort of 56 patients with cemented Nex Gen Legacy posterior stabilised (LPS) flex fixed bearing TKA between March 2006 and May 2010. The aim of the study was to define an acceptable limit of rotation in total knee replacement.MethodsRotational alignment was calculated using the Berger protocol with post operative computerised tomography scanning. The alignment parameters measured were tibial and femoral component rotations and the combined component rotations and the component rotational mismatch.ResultsThe two cohorts were demographically matched. Excessive internal rotation of the components was defined using the tenth percentile of rotations in the control cohort. Values of excessive internal rotation were 5.8° of the tibial component, 3.9° of the femoral component, 8.7° of combined rotation and 5.6° of the component mismatch. No significant difference was identified in excessive external rotation in any of the parameters. A significant difference in the mean rotations between the two cohorts was identified with internal rotation of the components in the painful cohort and external rotation on the control cohort.ConclusionsWe identified internal rotation malalignment of the tibial (p = 0.0003) and femoral (p = 0.014) components individually as well as the combined component rotation (p = 0.0003) and component rotation mismatch (p = 0.0001) to be a factor in pain following TKA. External rotation of any of the component parameters was not identified to be a factor in painful TKA. This study adds to the understanding of rotational alignment in TKA and suggests limits of internal rotation alignment associated with painful Nex Gen Legacy posterior stabilised (LPS) flex fixed bearing TKA.Level of evidenceLevel III.     

An evidence-based recommendation for the inclusion of specific local intrinsic factors in the study of knee osteoarthritis

ObjectiveAdequate characterization of the mechanical environment of the knee with osteoarthritis (OA) is important. These local intrinsic factors are difficult to measure and there is little evidence to guide their selection. This study makes an evidence-based recommendation for the inclusion of specific factors in the future study of knee OA.MethodForty-six subjects with knee OA were examined. Observed function was measured by the Timed Chair Rise (TCR). Self-reported function was measured by the WOMAC Function Scale and pain was measured by the WOMAC Pain Scale. Local intrinsic factors measured included varus/valgus alignment, anterior/posterior (A/P) laxity, proprioception, isometric knee extension (KE) strength, isometric knee flexion (KF) strength, and knee range of motion (ROM).ResultsFactors were recommended for inclusion in future research if they were significantly correlated with at least one measure of function or pain and if the factor made a significant unique contribution to a regression model when more than one local intrinsic factor was correlated with the same measure of function or pain. Alignment was correlated with pain (r = 0.48, p = 0.001) and WOMAC function (r = 0.38, p = 0.009). A/P laxity was correlated with pain (r = 0.30, p = 0.04) and WOMAC function (r = 0.37, p = 0.01). Knee ROM was correlated to WOMAC function (r = ? 0.35, p = 0.02). KE strength was correlated with TCR (r = 0.32, p = 0.03). Alignment made a significant contribution to prediction of pain (p = 0.003). A/P laxity (p = 0.004) and ROM (p = 0.008) made a significant contribution to WOMAC function.ConclusionWe recommend future knee OA studies include the variables varus/valgus alignment, A/P laxity, ROM, and KE strength.Level of EvidenceIII (correlational study).     

Baseline varus deformity is associated with increased joint loading and pain of non-operated knee two years after unilateral total knee arthroplasty

Background

The goals of this study were (1) to document the gait pattern of patients with unilateral knee osteoarthritis (OA), (2) to determine the knee adduction moment (KAM) changes in the non-operated knee, and (3) to identify the predictors of change in KAM in the non-operated knee.

Comparison the effect of lateral wedge insole and acupuncture in medial compartment knee osteoarthritis: A randomized controlled trial

BackgroundThere is lack of well-designed trials evaluating structural benefits of non-pharmacologic therapies in knee osteoarthritis (OA). In this parallel-group randomized controlled trial, we aim to compare the possible advantages of lateral wedge insole and acupuncture in patients with medial knee OA.MethodPatients with grade two or three of medial knee OA were randomly allocated to group one who received an in shoe lateral wedge and group two who underwent acupuncture. We assessed patients' pain, function and knee joint cartilage thickness before and after intervention. Paired t-test and independent samples t-test were used for in group and between group analyses. (Level of evidence: 2.)ResultsTwenty patients in each group were recruited in the study. Pain significantly decreased after therapy in both groups one and two (paired t test, P < 0.001, 95% CI: 1.62–3.25 and 1.58–3.20 respectively). Function improved in each group (paired t test, P = 0.001, 95% CI of 0.94–2.38 in group one and 0.97–2.43 in group two). A non-clinically statistically significant difference regarding the femoral and tibial cartilage thickness was obtained in both groups one (P = 0.005, CI: − 0.43–0.82 and P = 0.037, CI: − 0.44–0.80 respectively) and two (P = 0.025, CI: − 0.45–0.79 and P = 0.035, CI: − 0.29–0.96 respectively). Between groups analysis showed no significant difference regarding abovementioned measures.ConclusionBoth lateral wedge insole and acupuncture can be effective in the treatment of medial knee osteoarthritis without any superiority of one over the other.Iranian Registry of Clinical Trials: IRCT201201108235N1.URL: http://irct.ir/searchen.php     

Frontal plane knee mechanics and medial cartilage MR relaxation times in individuals with ACL reconstruction: A pilot study

BackgroundThe objective of this pilot study was to evaluate cartilage T_1ρ and T₂ relaxation times and knee mechanics during walking and drop-landing for individuals with anterior cruciate ligament reconstruction (ACL-R).MethodsNine patients (6 men and 3 women, age 35.8 ± 5.4 years, BMI 23.5 ± 2.5 kg/m²) participated 1.5 ± 0.8 years after single-bundle two-tunnel ACL reconstruction. Peak knee adduction moment (KAM), flexion moment (KFM), extension moment (KEM), and peak varus were calculated from kinematic and kinetic data obtained during walking and drop-landing tasks. T_1ρ and T₂ times were calculated for medial femur (MF), and medial tibia (MT) cartilage and compared between subjects with low KAM and high KAM. Biomechanical variables were compared between limbs.ResultsThe high KAM group had higher T_1ρ for MT (p = 0.01), central MT (p = 0.05), posterior MF (p = 0.04), posterior MT (p = 0.01); and higher T₂ for MT (p = 0.02), MF (p = 0.05), posterior MF (p = 0.002) and posterior MT (p = 0.01). During walking, ACL-R knees had greater flexion at initial contact (p = 0.04), and lower KEM (p = 0.02). During drop-landing, the ACL-R knees had lower KAM (p = 0.03) and KFM (p = 0.002).ConclusionPatients with ACL-R who have higher KAM during walking had elevated MR relaxation times in the medial knee compartments. These data suggest that those individuals who have undergone ACL-R and have higher frontal plane loading, may be at a greater risk of knee osteoarthritis.     

The effect of medial condylar bone loss of the knee on coronal plane stability--a cadaveric study

IntroductionThe quantitative effects of medial bone loss of the knee on both leg alignment and coronal plane stability are poorly understood.Materials and methodsUtilizing computer navigation, 5 mm bone defects of the medial distal femur (MDF), medial posterior femoral condyle (MPF), and medial tibial plateau (MT) were simulated in 10 cadaveric limbs, and alignment of the knee at various degrees of flexion were analyzed when applying standardized varus and valgus loads.ResultsThe 5 mm MPF defect significantly increased varus laxity at 90° of flexion by 3.3° ± 1.2° (p = 0.019), a 5 mm MDF defect resulted in a 2.2° ± 1.7° (p = 0.037) and a 2.1° ± 1.3° (p = 0.023) increase in laxity at 0° and 30° of flexion, respectively, and a 5 mm MT defect increased varus laxity at all flexion angles by 4.0° to 7.0°, but was only statistically significant at 30° (p = 0.026).DiscussionThis study confirms and quantifies the theories of flexion and extension gap balancing, and pseudolaxity of the medial collateral ligament in the varus knee, the results of which can be used in preoperative planning and intraoperative decision making for both total knee and unicondylar arthroplasty.     

Lateral and patellofemoral compartment osteoarthritis progression after medial unicompartmental knee arthroplasty: A five- to 10-year follow-up study

BackgroundThe purpose of the study was to evaluate lateral and patellofemoral osteoarthritis (OA) progression after medial unicompartmental knee arthroplasty (UKA) and identify factors affecting the progression that were not identified previously.MethodsWe evaluated 146 patients who underwent medial UKA between 2009 and 2014. Kellgren–Lawrence grading of lateral and patellofemoral OA was performed on preoperative and final follow-up knee radiographs. Radiographic and clinical characteristics, SF-36, and Oxford knee scores were compared between the OA progressed and non-progressed groups. Risk factors for lateral and patellofemoral OA progression were evaluated.ResultsThe lateral OA progressed and non-progressed groups significantly differed in side, preoperative flexion contracture, preoperative joint line convergence angle, postoperative tibiofemoral angle, insert size, revision status (P < 0.05), and the patellofemoral OA progressed and non-progressed groups significantly differed in age, pre- and postoperative flexion contracture, postoperative tibiofemoral angle and pre- and postoperative patellofemoral OA grade (P < 0.05). At the final follow-up, Visual Analogue Scale, Oxford Knee Scores, and SF-36 sub-scores were significantly better in the lateral OA non-progressed group (P < 0.001).Dominant leg (odds ratio (OR): 2.759), insert size (> 4, OR: 2.219), revision status (+, OR: 6.692), and postoperative tibiofemoral angle (> 5.5°, OR: 1.177) were independent risk factors for lateral OA progression, whereas age (> 60 years, OR: 3.222), preoperative patellofemoral OA grade (> 1, OR: 2.085), and postoperative flexion contracture (> 10°, OR: 1.919) were those for patellofemoral OA progression.ConclusionsMild radiographic progression of 1 KL grade is frequently seen five to 10 years after medial UKA. Postoperative outcomes are significantly affected by lateral compartment OA progression but not by patellofemoral OA progression.     

Biomechanics of single-tunnel double-bundle anterior cruciate ligament reconstruction using fixation with a unique expandable interference screw

BackgroundSingle-tunnel double-bundle (STDB) anterior cruciate ligament (ACL) reconstruction can restore biomechanical function and anatomic structure, but existing methods of graft fixation are not adequate. The aims of this study are to examine knee biomechanics after STDB reconstruction using a unique expandable interference screw for fixation.MethodsThe biomechanical parameters of six pairs of human cadaveric knee specimens were measured with the ACL intact, after ACL removal, and after STDB reconstruction using the interference screw or single-tunnel single-bundle (STSB) reconstruction. Anterior tibial translation under 134 N anterior tibial load in a neutral position as well as in 15° and 30° internal and external knee rotation and the internal tibial rotation angle under the rotatory load (5 N · m internal tibial rotation) were measured.ResultsAnterior tibial translations at each degree of knee flexion in the STDB group were significantly less than in the STSB group (all, P < 0.05). The internal rotation angles in the STSB group at five flexion angles were significantly higher than in the ACL intact group, whereas there were significantly less than those of the ACL absent group (P < 0.05). Under rotatory loads in the neutral position, the tibial internal rotation angles of the STDB group were significantly lower than in the STSB group at all flexion angles (all, P < 0.05).ConclusionsSTDB ACL reconstruction with the expandable interference screw provides better anteroposterior and rotational stability than STSB reconstruction.Clinical relevanceThe technique provides the advantages of double-bundle reconstruction using a single-tunnel technique.