Postoperative Valgus Alignment Research Articles

Achieving Better Clinical Outcomes After Total Knee Arthroplasty in Knees with Valgus Deformity: The Role of Alignment Strategies.

Personalized alignment in total knee arthroplasty (TKA) has demonstrated good functional outcomes for knees with varus alignment. However, limited research has explicitly addressed optimal alignment strategies for valgus knees. The aims of the current study were to assess the impact of the postoperative knee alignment and of the degree of correction of knee alignment on functional outcomes and satisfaction in a population with preoperative valgus and to evaluate the complication and revision rates based on postoperative alignment. This retrospective study included primary posterior-stabilized TKA with a preoperative hip-knee-ankle (HKA) angle of ≥180°, with a minimum follow-up of 32 months. There were 460 knees included, divided into 3 groups: (1) preoperative neutral alignment (180° to 183°) (n = 162), (2) preoperative mild valgus (184° to 190°) (n = 204), and (3) preoperative severe valgus (>190°) (n = 94). A standardized surgical technique was employed with a goal of achieving neutral postoperative alignment. Data on radiographs, Knee Society Scores (KSS), range of motion, satisfaction, complications, and revisions were collected at the last follow-up. The mean follow-up was 74.3 ± 12.4 months. In the preoperative mild valgus group, 10.8% of patients had postoperative varus, 81.4% had postoperative neutral alignment, and 7.8% had postoperative valgus. In the preoperative severe valgus group, 4.3% had postoperative varus, 83.0% had postoperative neutral alignment, and 12.8% had postoperative valgus. In the preoperative mild valgus group, patients with postoperative neutral alignment had significantly higher satisfaction (p = 0.0004) and KSS function score (p = 0.031) than patients with postoperative valgus alignment. In the preoperative severe valgus group, patients with postoperative valgus alignment had significantly higher satisfaction (p = 0.035) and greater improvement of the KSS knee score (p = 0.014) than patients with postoperative neutral alignment. Functional outcomes were not impacted by the degree of HKA angle correction. There were significantly fewer complications (p = 0.022) and revisions (p = 0.007) in the preoperative mild valgus group when patients had a postoperative neutral alignment compared with a postoperative valgus alignment. For preoperative mild valgus, correction to neutral alignment achieved better outcomes and fewer complications than leaving residual valgus. For preoperative severe valgus, retaining residual valgus postoperatively ensured satisfactory functional outcomes without increased complications. Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Alignment in Total Knee Arthroplasty: Avoid Crossing Over From Varus to Valgus

BackgroundIdeal target limb alignment remains a debated topic in total knee arthroplasty (TKA). We aimed to determine the effect of limb alignment correction on patient-reported outcomes and knee range of motion (ROM) following TKA. MethodsIn this retrospective analysis, patients (N = 409) undergoing primary TKA at a single institution were studied. Using full leg-length radiographs, limb alignment was measured preoperatively and postoperatively. Patients were categorized by preoperative (Preop) alignment (varus > 0°; valgus < 0°). Preop varus patients were then divided as follows based on postoperative alignment: neutral (VAR-NEUT, 0°± 2), remaining in varus (VAR-rVAR, ≥3°), and cross-over to valgus (VAR-CO, ≤−3°). Similarly, Preop valgus patients were divided as follows for postoperative alignment: neutral (VAL-NEUT, 0°± 2), remaining in valgus (VAL-rVAL, ≤−3°), and cross-over to varus (VAL-CO, ≥3°). The Knee Injury and Osteoarthritis Outcome Score for Joint Replacement survey scores were collected at preoperatively as well as at 6 weeks, 3, 6, and 12 months postoperatively. Knee ROM was collected at 2 weeks, 6 to 12 weeks, and >6 months postoperatively. An analysis of variance repeated on time followed by a Bonferroni post hoc test was used to compare outcomes for the postoperative alignment subgroups. ResultsPreop Varus patients: Those in the VAR-CO group (overcorrected to −4.03° ± 1.95valgus) were observed to have lower Knee Injury and Osteoarthritis Outcome Score for Joint Replacement scores at 3, 6, and 12 months postoperatively compared to those in the NEUT group (P < .05). This finding was paired with reduced ROM at 6 to 12 weeks postoperatively in the VAR-CO group compared to VAR-NEUT and VAR-rVAR (P < .05). Preop Valgus patients: Those in the VAL-rVal group (left in −4.39° ± 1.39valgus) were observed to have reduced knee flexion at 6 to 12 weeks postoperatively compared to VAL-NEUT and VAL-CO. ConclusionsThese findings indicate that postoperative valgus alignment via either crossing over to valgus (VAR-CO) or remaining in valgus (VAL-rVAL) alignment may result in less preferable outcomes than correction to neutral or slightly varus alignment.

Postoperative Decrease in Bone Marrow Lesion Associated With Better Clinical Outcomes Following Medial Open-Wedge High Tibial Osteotomy

PurposeThe aim of the current study was to assess serial changes of preoperative bone marrow lesion(BML) following medial open-wedge high tibial osteotomy(MOWHTO) up to 2 years and evaluate whether postoperative change of BML affected patient-reported outcome measures(PROMs) till the 2 years follow-up. Factors related to the postoperative changes in BML were also evaluated. MethodsCurrent study retrospectively assessed prospectively collected data of consecutive patients between December 2016 and March 2018 who underwent MOWHTO for symptomatic knee osteoarthritis with varus malalignment(≥5°) and minimum 2-year follow-up. Serial MRIs at preoperative and postoperative 3, 6, 18, and 24 months were performed and the extent of BML was evaluated consecutively using two validated methods. Clinically, preoperative and postoperative PROMs and their achievement of minimal clinically important difference(MCID) values were evaluated. The associations of the extent of BMLs with PROMs at each follow-up period over time were analyzed using a linear mixed model. Furthermore, factors related to the postoperative changes of BML were assessed. ResultsOf 26 patients, 21(80.8%) had preoperative BML at medial femoral and tibial condyles. The postoperative decrease in BML was noted in 17(81.0%) and 18(85.7%) at medial femoral and tibial condyles. The BML decreased at postoperative 3 months and thereafter, the extent of BML gradually reduced until postoperative 24 months. The proportion of patients achieved MCID was 84.6% for total WOMAC scores and 80.8%, 76.9%, and 84.6% for KOOS symptom, pain, and activity of daily living subscales. Postoperative decrease in BML was significantly associated with better PROMs over postoperative 24 months. Furthermore, normo-correction(2°–5° valgus) was a significant factor for decreased BML following MOWHTO. ConclusionPreoperative BML gradually decreased with time following MOWHTO, and the postoperative decrease in BML related with better PROMs over postoperative 24 months. Moreover, postoperative valgus alignment was a significant factor relating the postoperative decrease of BML.

Valgus Drift after Total Ankle Arthroplasty

Category:Ankle; Ankle ArthritisIntroduction/Purpose:Total ankle arthroplasty (TAA) is a common treatment for ankle arthritis, but many challenges exist when attempting to correct and balance coronal plane deformity. Varus ankle arthritis tends to be stiffer and often leads to a more stable TAA, but valgus ankle arthritis tends to have more laxity especially in the setting of a progressive collapsing foot deformity. Failure to achieve appropriate deformity correction and soft tissue balance can result in recurrence of the deformity with valgus drift. The purpose of this study was to evaluate the longitudinal coronal plane alignment as well as outcomes in patients treated with TAA with resultant valgus drift.Methods:98 patients who underwent TAA for valgus ankle arthritis were identified through a prospectively collected database. All patients had a minimum of 2 year follow-up. The tibiotalar angle was measured on preoperative radiographs to include patients with valgus ankle arthritis five degrees or greater. Radiographic alignment in the postoperative period was compared to the alignment at final follow-up. Complications, failures, revisions, and reoperations were recorded. Patients were categorized by severity of preoperative valgus deformity into 3 groups: 5-10 degrees, 11-20 degrees, and greater than 20 degrees. Valgus drift was defined as greater than 5 degrees of valgus shift at final follow-up when compared to the postoperative alignment. Median follow- up was 49.2 (37.2-68.3 inner quartile) months.Results:Patients with greater than 20 degrees of preoperative valgus deformity had an initial postoperative alignment of 2 degrees of valgus and ended with an average of 5.5 degrees of valgus at final follow-up. The groups of patients with 5-10 degrees as well as 11-20 degrees of valgus were corrected to neutral (0 degrees) in the initial post-op period and ended with a final postoperative valgus alignment of 2.5 degrees and 2 degrees, respectively. Overall, 16 patients (18%) had greater than 5 degrees of valgus drift after their surgery, of which 2 failed and were revised (13%) and 5 had reoperations (31%).Conclusion:All groups of preoperative valgus deformity severity had some valgus shift overall at final follow-up. The most severe preoperative valgus deformities were least likely to be corrected to neutral with the index procedure and also on average drifted back to over 5 degrees of valgus. Patients with valgus drift after TAA can still have a good result but should be monitored closely. Overall, they did not have a high failure rate. This study emphasizes the necessity of correcting both the ankle and foot deformity when performing TAA for valgus ankle arthritis in order to maintain deformity correction.

Does postoperative quantitative bone scintigraphy reflect outcomes following medial open-wedge high tibial osteotomy?

PurposeThe present study evaluated changes in bone tracer uptake (BTU) after medial open-wedge high tibial osteotomy (MOWHTO) and determined whether postoperative BTU correlates with clinical symptoms, radiologic parameters, or cartilage regeneration following MOWHTO.MethodsA total of 210 knees underwent MOWHTO for medial compartmental osteoarthritis (OA) were enrolled in this study. Mean follow-up period was 42.7 months. We assessed BTU for the medial compartment of the knee before MOWHTO and at the time of plate removal. Radiologic parameters included Kellgren-Lawrence (K-L) grade and Hip-Knee-Ankle angle (HKAA). Clinical evaluation included American Knee Society (AKS) score and cartilage status was graded at the time of MOWHTO and second-look arthroscopy according to the International Cartilage Repair Society (ICRS) grading system and articular cartilage regeneration stage. Statistical analysis performed to assess the relationships among postoperative BTU of the medial compartment, radiologic parameters, arthroscopic changes and clinical outcomes.ResultsBTU of medial femoral condyle and tibial plateau were significantly decreased at 2 years after MOWHTO (p<0.001). AKS scores and arthroscopic cartilage status were also significantly improved following MOWHTO. BMI and postoperative HKAA showed significant correlations with postoperative changes of BTU in uni- and multi-variable analysis. Meanwhile, postoperative changes of BTU did not show significant correlation with clinical outcomes or cartilage regeneration following MOWHTO.ConclusionLower BMI and postoperative valgus alignment were significant predictor for postoperative BTU decrease of the medial compartment following MOWHTO. However, postoperative changes of BTU did not reflect cartilage regeneration or clinical outcomes until the midterm follow-up.

Lateral osteoarthritis progression is associated with a postoperative residual tibiofemoral subluxation in Oxford UKA.

Lateral compartment osteoarthritis progression (LOP) is a major complication after Oxford mobile-bearing unicompartmental knee arthroplasty (OUKA). This study aimed to identify the association between tibiofemoral subluxation (TFS) and LOP after OUKA. Patients whose TFS was uncorrectable according to preoperative stress radiographs were hypothesised to develop residual TFS even after surgery, and thought to be more likely to develop LOP. The study included 201 patients who underwent medial OUKA. Fifteen patients showed increases in LOP of at least two Kellgren-Lawrence grades after surgery [progression (P) group], while the others had no progression (N group, n = 186). TFS was measured on preoperative full leg weight-bearing radiographs, valgus stress radiographs and postoperative plain radiographs. Valgus stress radiographs were obtained using a firm manual valgus force with the knee flexed at 20°. Leg alignment, Oxford knee score (OKS), and revision rates were assessed. The P group had significantly higher TFS values on preoperative valgus stress (6.8° ± 2.2° vs. 4.5° ± 2.0°; P < 0.001) and postoperative radiographs (6.6° ± 2.3° vs. 4.6° ± 2.9°; P < 0.001) than the N group. Patients with postoperative residual TFS and postoperative valgus alignment were more likely to have LOP, but 9 of the 15 LOP patients did not show postoperative valgus alignment. The P group had significantly poorer postoperative OKS (33.0 ± 10.2 vs. 37.4 ± 6.5, P = 0.017) and a higher rate of revision (6/15 vs 6/186; odds ratio = 19.16; 95% CI = 4.98-76.05, P < 0.001). OA progression in the lateral compartment after medial OUKA might be associated with postoperative residual TFS, but does not always coexist with postoperative valgus alignment. Preoperative assessment of TFS with valgus stress could be a potential predictor of postoperative residual TFS and LOP. Level III.

Differences in impact on adjacent compartments in medial unicompartmental knee arthroplasty versus high tibial osteotomy with identical valgus alignment

BackgroundIt is unclear why medial unicompartmental knee arthroplasty (UKA) with postoperative valgus alignment causes adjacent compartment osteoarthritis more often than high tibial osteotomy (HTO) for moderate medial osteoarthritis of the knee with varus deformity. This study used a computer simulation to evaluate differences in knee conditions between UKA and HTO with identical valgus alignment. MethodsDynamic musculoskeletal computer analyses of gait were performed. The hip–knee–ankle angle in fixed-bearing UKA was changed from neutral to 7° valgus by changing the tibial insert thickness. The hip–knee–ankle angle in open-wedge HTO was also changed from neutral to 7° valgus by opening the osteotomy gap. ResultsThe lateral tibiofemoral contact forces in HTO were larger than those in UKA until moderate valgus alignments. However, the impact of valgus alignment on increasing lateral forces was more pronounced in UKA, which ultimately demonstrated a larger lateral force than HTO. Valgus alignment in UKA caused progressive ligamentous tightness, including that of the anterior cruciate ligament, resulting in compression of the lateral tibiofemoral compartment. Simultaneously, patellofemoral shear forces were slightly increased and excessive external femoral rotation against the tibia occurred due to the flat medial tibial insert surface and decreased lateral compartment congruency. By contrast, only lateral femoral slide against the tibia occurred in excessively valgus-aligned HTO. ConclusionsIn contrast to extra-articular correction in HTO, which results from opening the osteotomy gap, intra-articular valgus correction in UKA with thicker tibial inserts caused progressive ligamentous tightness and kinematic abnormalities, resulting in early osteoarthritis progression into adjacent compartments.

Predictors of Satisfactory Outcomes With Fixed-Bearing Lateral Unicompartmental Knee Arthroplasty: Up to 7-year Follow-Up

BackgroundThere is little literature available examining factors that may predict functional recovery after lateral unicompartmental knee arthroplasty (UKA). The purpose of this study was to report short to mid-term effectiveness and evaluate predictors of better outcome following lateral UKA. MethodsWe retrospectively reviewed 248 patients (260 knees) who underwent lateral UKA from January 2013, with a mean 5-year follow-up. The primary outcome measures comprised the Hospital for Special Surgery (HSS) score and patient satisfaction. Multivariate regression analyses were implemented to investigate associations between these factors with a satisfactory outcome. Implant survival was estimated by Kaplan-Meier analysis. ResultsComplete follow-up was available for 186 patients (198 knees). At last follow-up, the HSS scores were changed from 52.1 (range, 38-80) preoperatively to 85.6 (range, 61-98) (P < .001), The OKS improved from 22.8 (range, 16-32) preoperatively to 42.7 (range, 30-47) postoperatively (P < .01). The 5-year survival was 99.5%. The multivariate analysis showed that the following factors tended to obtain a satisfactory outcome: higher proportion of ASA class I (P < .001), diagnosis of primary OA (P = .007), postoperative limb alignment (P = .007), and higher preoperative HSS score (P = .019). Patients with valgus 9°-12° reported the highest HSS scores among different subgroups (P < .001). ConclusionFollowing lateral UKA, postoperative outcomes were satisfactory in patients with lower ASA scores, diagnosis with primary OA, higher preoperative HSS scores and those with postoperative valgus alignment. It is important to understand these correlations to help appropriate patient selection to obtain optimal function after lateral UKA.

Prior high tibial osteotomy is not a contraindication for medial unicompartmental knee arthroplasty.

To report on the outcome and complications of minimal invasive medial unicondylar knee arthroplasty (UKA) after failed prior high tibial osteotomy (HTO) as treatment for medial osteoarthritis in the knee. The hypothesis was that good results can be achieved, if no excessive postoperative valgus alignment and abnormal proximal tibial geometry is present. All medial UKAs after failed prior HTO (n = 30), performed between 2010 and 2018 were retrospectively reviewed. The patients were followed for revision surgery and survival of the UKA (defined as revision to TKA). Clinical examination using the Knee Society Score (KSS), Oxford Knee Score (OKS) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), as well as radiological examination was performed. Radiographs were studied and the influence of the demographic factors and the radiographic measurements on the survival and the clinical outcome was analysed. After a follow-up of 4.3 ± 2.6years (2.1-9.9) 27 UKAs were available. The survival rate was 93.0%. Two UKAs were revised to TKA (excessive valgus alignment and tibial loosening with femoropatellar degeneration). Two further patients had revision surgery (hematoma and lateral meniscus tear). Follow-up clinical and radiological examination was performed in 21 cases: KSS 82.9 ± 10.1 (54.0-100.0), KSS (function) 93.3 ± 9.7 (70.0-100.0); OKS 42.7 ± 6.0 (25.0-48.0); WOMAC 7.9 ± 15.6 (0.0-67.1). No significant influence of demographic factors or radiological measurements on the clinical outcome was present. Prior HTO is not a contraindication for medial UKA, because good-to-excellent results can be achieved in selected patients with medial osteoarthritis and previous HTO, treated with medial UKA, in a midterm follow-up. Excessive mechanical valgus axis should be avoided; therefore, patient selection and accurate evaluation of medial laxity, preoperative mechanical axis, joint line convergence and proximal tibial geometry are important. III.

The proper correction of the mechanical axis in high tibial osteotomy with concomitant cartilage procedures\u2014a retrospective comparative study

BackgroundThe guidelines to correct the mechanical axis in high tibial osteotomy (HTO) have changed recently, and some studies have suggested that the correction of the mechanical axis should be based on the severity of cartilage defect. The purpose of this study was (1) to evaluate the radiographic and clinical outcomes of HTO with concomitant cartilage procedures and (2) to compare our method with conventional method regarding the mechanical axis correction.MethodsSixty-six knees which underwent opening wedge HTO with cartilage procedures were evaluated retrospectively. The mean age was 56.0 ± 8.3 years, and the average follow-up period was 35.9 ± 22.0 months (range, 24–93 months) with a minimum follow-up of 2 years. All patients were divided into two groups regarding the method of mechanical axis correction; the postoperative mechanical axis was shifted to 50–55% of the tibial plateau width in group I (n = 46) and to 62–66% according to the conventional method in group II (n = 20). Concomitant cartilage procedures were performed, and each technique of those was determined according to the cartilage status.ResultsThe functional scores and visual analog scale for pain in all patients showed a significant improvement at the final follow-up, but there was no significant difference between two groups. The postoperative mechanical axis was the valgus axis of 0.7° in group I with average mechanical axis deviation (MAD) of 51.7%, whereas the valgus axis of 4.2° in group II with average MAD of 64.0%. In patients who underwent second-look arthroscopy, the cartilaginous regeneration could be obtained by cartilage procedures.ConclusionIn HTO with concomitant cartilage procedures, the method to correct postoperative mechanical axis to the neutral or valgus axis less than 3° could be an effective and safe method to obtain reliable clinical outcomes without complications. Therefore, our method can be used as a selective technique to prevent complications related to the postoperative valgus alignment in patients who are needed much correction angle due to the preoperative severe varus alignment.Study designRetrospective comparative study, level III.

Does low-constraint mobile bearing knee prosthesis give satisfactory results for severe coronal deformities? A five to twelve year follow up study.

Severe varus and valgus knee deformities traditionally are replaced with constrained implants, with a number of disadvantages. We present our results in this challenging group using a low constraint deep-dish mobile bearing implant design. One hundred fifty-four patients (170 arthroplasties) who underwent primary TKA using a deep-dish, mobile bearing posterior-stabilized implant for severe varus (HKA < 170°) or valgus (HKA > 190°) deformity between 2004 and 2009 were evaluated at a mean of 6.6years post-operatively (minimum of 5years). Alignment improved from a pre-operative mean (±SD) varus deformity of 167.4° (±2.6°) and a mean (±SD) valgus deformity of 194.1° (±4.0°) to an overall mean (±SD) post-operative mechanical alignment of 178.6° (±3.2°). Twenty-three patients had post-operative varus alignment, five patients had post-operative valgus alignment and 134 knees were in neutral alignment (within 3° spread). Clinical scores at final follow-up were excellent (IKS score 93.8 (±7.4) and function score 82.4 (±20.2)). Three patients were re-operated upon: one deep infection, one periprosthetic fracture and one revision at 144months for aseptic loosening of the femoral component. No patient was revised for instability or implant failure. The survival rate at fiveyears was 99.4% and at tenyears 98.6%. Satisfactory outcomes can be achieved in patients with substantial varus or valgus deformities using low constraint deep-dish mobile bearing implant, standard approach and appropriate soft tissue releases.

Early functional outcome after lateral UKA is sensitive to postoperative lower limb alignment

The predictive role of patient-specific characteristics and radiographic parameters on medial unicompartmental knee arthroplasty (UKA) outcomes is well known, but knowledge of these predictors is lacking in lateral UKA. Therefore, purpose of this study was to assess the predictive role of these parameters on short-term functional outcomes of lateral UKA. In this retrospective cohort study, Western Ontario and McMaster Universities Arthritis Index scores were collected at 2-year follow-up (median 2.2years, range 2.0-4.0years) in 39 patients who underwent lateral UKA. Patient-specific characteristics included age, BMI and gender, while radiographic parameters included osteoarthritis severity of all three compartments and both preoperative and postoperative hip-knee-ankle alignment. BMI, gender, age and preoperative valgus alignment were not correlated with functional outcomes, while postoperative valgus alignment was correlated with functional outcomes (0.561; p=0.001). Postoperative valgus of 3°-7° was correlated with better outcomes than more neutral (-2° to 3° valgus) alignment (96.7 vs. 85.6; p=0.011). Postoperative alignment was a predictor when corrected for patient-specific characteristics (regression coefficient 4.1; p<0.001) and radiological parameters (regression coefficient 3.8; p=0.002). Postoperative valgus alignment of 3°-7° was correlated with the best short-term functional outcomes in lateral UKA surgery, while patient-specific parameters and preoperative alignment were not correlated with functional outcomes. Based on these findings, a surgeon should aim for valgus alignment of 3°-7° when performing lateral UKA surgery for optimal functional outcomes. Prognostic study, Level II.

Indices Affecting Outcome of Neglected Femoral Neck Fractures After Valgus Intertrochanteric Osteotomy

To evaluate preoperative neck resorption and postoperative valgus orientation as predictors of union and functional outcome after valgus intertrochanteric osteotomy for treatment of neglected femoral neck fractures and nonunions. Retrospective cohort study. Tertiary care center. Forty consecutive patients with neglected femoral neck fracture and nonunions were treated with valgus intertrochanteric osteotomy, and follow-up was available in 32 patients (average age, 43 years; range, 14-60 years; average nonunion duration, 6 ± 7 months; range, 1-36 months). Valgus intertrochanteric osteotomy. Clinical outcome was assessed with Harris hip score. Plain radiographs were evaluated for union, avascular necrosis, preoperative bone deficiency (neck resorption ratio), and postoperative femoral head fragment alignment (head-shaft angle). Follow-up at 5 ± 3 years (range, 2-12 years) after surgery showed union in 29 patients (91%), and Harris hip score was 82 ± 13 points (range, 63-100 points). The 3 patients with persistent nonunion at the neck of femur had neck resorption ratio <0.52. Increased postoperative head-shaft angle was associated with lower follow-up Harris hip score; postoperative valgus alignment >15 degrees compared with the contralateral side was associated with poor functional outcome. The presence of avascular necrosis did not affect the outcome. Valgus intertrochanteric osteotomy resulted in union and satisfactory functional outcome in most patients who had neglected femoral neck fractures and nonunions. Preoperative neck resorption ratio <0.5 was a risk factor for nonunion, and excessive valgus alignment was a risk factor for poor functional outcome after osteotomy. Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.

Are external knee load and EMG measures accurate indicators of internal knee contact forces during gait?

Mechanical loading is believed to be a critical factor in the development and treatment of knee osteoarthritis. However, the contact forces to which the knee articular surfaces are subjected during daily activities cannot be measured clinically. Thus, the ability to predict internal knee contact forces accurately using external measures (i.e., external knee loads and muscle electromyographic [EMG] signals) would be clinically valuable. We quantified how well external knee load and EMG measures predict internal knee contact forces during gait. A single subject with a force-measuring tibial prosthesis and post-operative valgus alignment performed four gait patterns (normal, medial thrust, walking pole, and trunk sway) to induce a wide range of external and internal knee joint loads. Linear regression analyses were performed to assess how much of the variability in internal contact forces was accounted for by variability in the external measures. Though the different gait patterns successfully induced significant changes in the external and internal quantities, changes in external measures were generally weak indicators of changes in total, medial, and lateral contact force. Our results suggest that when total contact force may be changing, caution should be exercised when inferring changes in knee contact forces based on observed changes in external knee load and EMG measures. Advances in musculoskeletal modeling methods may be needed for accurate estimation of in vivo knee contact forces.

TIBIAL OSTEOTOMY FOR THE TREATMENT OF VARUS GONARTHROSIS

The purpose of this retrospective study was to assess the long-term results after the treatment of medial compartment gonarthrosis with a proximal tibial osteotomy to determine whether various clinical and radiographic factors relate to the outcome. From 1972 to 1990, seventy-six valgus-producing high tibial osteotomies were performed in sixty-six patients with medial compartment gonarthrosis. Stabilization was achieved with use of a plate on the lateral side of the proximal part of the tibia and a figure-of-eight wire on the medial side. The mean age of the patients at the time of surgery was sixty-nine years, and the mean duration of follow-up was 10.8 years. The factors that were analyzed included postoperative valgus alignment; the age, gender, and weight of the patient; preoperative Ahlbäck radiographic grade; adverse events; Workers' Compensation status; and public liability. Survivorship outcome end points were conversion to arthroplasty, a Hospital for Special Surgery knee score of <70 points, and patient dissatisfaction with the procedure. Ten-year survival, according to the life-table method, was 74%, 70%, and 65% with conversion to arthroplasty, a Hospital for Special Surgery knee score of <70 points, and patient dissatisfaction, respectively, as the end points. Radiographic valgus alignment that ranged between 8 degrees and 16 degrees at one year after the osteotomy had the most significant positive effect on survivorship for all end points (p < 0.01) compared with the other parameters. Complications occurred in sixteen (21%) of the seventy-six procedures, and they had a significant effect on survival, with all three end points (p < 0.05). We found that survival at ten years was 90% (95% confidence interval, 80% to 99%) when the radiographic valgus angle at one year was between 8 degrees and 16 degrees with arthroplasty as the end point. We believe that there is a role for tibial osteotomy, as an alternative to total knee arthroplasty, in patients who are less than sixty years old. Therapeutic study, Level III-2 (retrospective cohort study). See Instructions to Authors for a complete description of levels of evidence.

Patellofemoral complications after posterior-stabilized total knee arthroplasty: A comparison of 2 different implant designs

We conducted a retrospective review of 2 consecutive series of posterior-stabilized total knee arthroplasties (TKAs) to evaluate patellofemoral complications, in particular, significant patellofemoral crepitance or patellar clunk syndrome. Twenty posterior-stabilized Axiom PSK (Wright Medical Technology, Arlington, TN) TKAs (group 1) were compared with 20 posterior cruciateNsacrificed Advance medial pivot (Wright Medical Technology, Arlington, TN) TKAs (group 2). The average age in group 1 was 69 years and in group 2 was 70 years. Preoperative valgus alignment in group 1 was 7.5° and in group 2 was 1.3°. Postoperative valgus alignment for the 2 groups was 4.8° and 5.3° valgus. Postoperative patellar tilt for the 2 groups was 0.9° lateral tilt and 8° lateral tilt. Patellofemoral signs of crepitance ≥2+ and significant box impingement complaints of either snapping or clunking decreased significantly postoperatively from 5 of 20 (25%) in group 1 to 0 of 20 in group 2 (P=.0079). Copyright 2002, Elsevier Science (USA). All rights reserved.