Mean Medial Proximal Tibial Angle Research Articles

Association Between Femoral Component Sagittal Positioning and Anterior Knee Pain in Total Knee Arthroplasty: A 10-Year Case-Control Follow-up Study of a Cruciate-Retaining Single-Radius Design.

Background:Anterior knee pain is the most common complication of total knee arthroplasty (TKA). The purpose of this study was to assess whether sagittal femoral component position is an independent predictor of anterior knee pain after cruciate-retaining single-radius TKA without routine patellar resurfacing.Methods:A prospective cohort study of 297 cruciate-retaining single-radius TKAs performed in 2006 and 2007 without routine patellar resurfacing identified 73 patients (25%) with anterior knee pain and 89 (30%) with no pain (controls) at 10 years. Patients were assessed preoperatively and at 1, 5, and 10 years postoperatively using patient-reported outcome measures (PROMs), including the Short Form-12 (SF-12), Oxford Knee Score (OKS), and satisfaction and expectation questionnaires. Variables that were assessed as predictors of anterior knee pain included demographic data, the indication for the TKA, early complications, stiffness requiring manipulation under anesthesia, and radiographic criteria (implant alignment, Insall-Salvati ratio, posterior condylar offset ratio, and anterior femoral offset ratio).Results:The 73 patients with anterior knee pain (mean age, 67.0 years [range, 38 to 82 years]; 48 [66%] female) had a mean visual analog scale (VAS) score of 34.3 (range, 5 to 100) compared with 0 for the 89 patients with no pain (mean age, 66.5 years [range, 41 to 82 years]; 60 [67%] female). The patients with anterior knee pain had mean femoral component flexion of −0.6° (95% confidence interval [CI] = −1.5° to 0.3°), which differed significantly from the value for the patients with no pain (1.42° [95% CI = 0.9° to 2.0°]; p < 0.001). The patients with and those without anterior knee pain also differed significantly with regard to the mean anterior femoral offset ratio (17.2% [95% CI = 15.6% to 18.8%] compared with 13.3% [95% CI = 11.1% to 15.5%]; p = 0.005) and the mean medial proximal tibial angle (89.7° [95% CI = 89.2° to 90.1°] compared with 88.9° [95% CI = 88.4° to 89.3°]; p = 0.009). All PROMs were worse in the anterior knee pain group at 10 years (p < 0.05), and the OKSs were worse at 1, 5, and 10 years (p < 0.05). Multivariate analysis confirmed femoral component flexion, the medial proximal tibial angle, and an Insall-Salvati ratio of <0.8 (patella baja) as independent predictors of anterior knee pain (R2 = 0.263). Femoral component extension of ≥0.5° predicted anterior knee pain with 87% sensitivity.Conclusions:In our study, 25% of patients had anterior knee pain at 10 years following a single-radius cruciate-retaining TKA without routine patellar resurfacing. Sagittal plane positioning and alignment of the femoral component were associated with long-term anterior knee pain, with femoral component extension being a major risk factor.Level of Evidence:Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Tibial bowing and tibial component placement in primary total knee arthroplasty in valgus knees: Are we overlooking?

Tibial bowing in valgus knees with arthritis can lead to component malplacement during total knee arthroplasty (TKA). Incidence of valgus knees with medial tibial bowing, its effect on tibial component placement during primary TKA and methods to improve accuracy of the component placement were studied. Full-length weight-bearing alignment radiograph was taken in 117 patients (149 knees) with valgus deformity undergoing TKA. In these cases, the proximal tibial reference for extramedullary jig placement was planned preoperatively with reference to the tibial spines and classified as four zones. The mean preoperative hip-knee-ankle (HKA) angle was 192.9° (180.3-234.5°). Bowing >3° was considered significant (p < 0.001) and at this level of bowing, the proximal tibial reference was shifted from centre to medial. Tibial bowing <3° was considered straight and >3° as tibia valga. Tibia was bowed in 70 knees (46.97%). Severity of valgus deformity had strong positive correlation with the tibia valga (p < 0.001). The post-operative medial proximal tibial angle (MPTA) and HKA angle were 91.63° (87.9-95.7°) and 182.6° (178.1-189.7°), respectively. The mean MPTA and post-operative HKA angle in bowed and straight tibiae were 90.35° versus 89.78° (p = 0.547) and 181.5° versus 180.7° (p = 0.5716), respectively, and the difference was not statistically significant. Medial tibial bowing is very common in valgus knees. Tibia valga has a strong positive correlation with the severity of valgus deformity. Accurate tibial component placement can be achieved with a medialized reference point for extramedullary tibial cutting jig in knees with significant tibia valga. The study has been registered in clinical trials registry - India (CTRI/2018/03/012283).

Improving the accuracy of tibial component placement during total knee replacement in varus knees with tibial bowing: A prospective randomised controlled study

BackgroundLateral tibial bowing leads to varus placement of the tibial component during total knee replacement in varus knees. Lateralised tibial jig placement can improve the accuracy of the tibial cut. MethodsA total of 227 patients (300 knees) undergoing total knee replacements were randomised into two groups. In the study group, the point of intersection of the distal tibial diaphyseal line at the tibial plateau drawn on long films was represented by zones. Knees with femoral bowing >5° (28%) were excluded. Tibial jig placement on the proximal tibia was lateralised according to the zones. In the control group, the mid-point of the tibial plateau was taken as a reference. Femoral and tibial bowing, postoperative limb alignment and component placement were assessed. ResultsOf the 216 knees that were studied, 106 were in the study group and 110 in the control group. Bowing ≥3° had a significant positive correlation with lateralisation of the proximal tibial reference (p < 0.001). The Incidence of tibial bowing ≥3° was 57.33%. The mean postoperative hip–knee–ankle (HKA) angle was 178.31 ± 2.88° and 176.53 ± 2.88° (p < 0.001), whereas the mean medial proximal tibial angle (MPTA) was 89.91 ± 1.42° and 88.79 ± 1.72° (p < 0.001) in the study and control groups, respectively. Considering bowed tibiae alone, HKA angle and MPTA in the study group were 178.08 ± 2.81° and 89.72 ± 1.39° compared with 175.88 ± 2.87° and 88.38 ± 1.38° in the control group (p < 0.001). ConclusionThere is a high incidence of tibial bowing in varus knees. Lateralised tibial jig placement improved tibial component placement and postoperative limb alignment in total knee arthroplasty in varus knees with tibial bowing.

Anatomical Adaptation of Fibula and its Mechanism of Proximal Partial Fibulectomy Associated with Medial Compartment Knee Osteoarthritis.

ObjectivesTo reveal the anatomical adaptation of the fibula and its relations to age and settlement of the medial tibial plateau, and to explore the mechanism of proximal partial fibulectomy in treating medial compartment knee osteoarthritis (OA).MethodsA retrospective study was performed in the Third Hospital of Hebei Medical University. Weight‐bearing full‐leg anteroposterior (AP) radiographs of 280 adults (560 knees) obtained from 1 January 2018 to 31 October 2018 were enrolled according to our inclusion and exclusion criteria, including 157 men and 123 women, with an average age of 50.3 ± 14.8 years (range, 19–80 years). Radiographic severity of knee OA was assessed using Kellgren and Lawrence (K–L) grading. The settlement of the medial tibial plateau was evaluated using the medial proximal tibial angle (MPTA). Curvatures of the tibia and the fibula were measured as proximal tibial curvature (PTC), distal tibial curvature (DTC), proximal fibular curvature (PFC), and distal fibular curvature (DFC). Two orthopaedic surgeons performed all the radiological measurements for 30 randomly selected patients, and repeated the measurements 1 week later. Based on the satisfactory intra‐observer and inter‐observer reliabilities (ICC > 0.9), each parameter was analyzed in this study. Multivariable linear regression models were used to examine relations between radiological measurements and age.ResultsThe mean MPTA, PTC, DTC, PFC, and DFC were 85.4° ± 2.8°, 176.2° ± 1.9°, 176.8° ± 1.8°, 176.8° ± 1.9°, and 177.0° ± 2.0°, respectively. Ninety‐three knees of K–L grade I were categorized as non‐knee OA, and 467 knees of K–L grades II–IV were categorized as knee OA. The MPTA, PTC, and PFC of the knee OA group were significantly smaller than those of non‐knee OA group (P < 0.05). The K–L grade of knee OA significantly increased with age (χ 2 = 182.169, P < 0.01). The multivariate linear regression analysis indicated that the MPTA and fibular curvatures were negatively correlated with age (the regression equation is age = 561.165–0.945 MPTA‐0.937 PFC‐0.959 DFC, P < 0.05), and the MPTA was negatively correlated with PFC (the regression equation is MPTA = 7.827 + 0.099 DFC, P < 0.05).ConclusionsThe proximal curve of the fibula increased in patients with medial compartment knee OA, and this change was positively correlated with age and settlement of the medial tibial plateau. This anatomical adaptation of the fibula was associated with greater fibular axial load and the pulling from the peroneus longus. The proximal partial fibulectomy procedure effected a receptive foot pronation to reduce KAM and rebalance the biceps‐proximal fibula–peroneus longus complex, consequently achieving medial compartment unloading.

A pilot study to assess the safety and radiological performance of a new low-profile locking plate for high tibial osteotomy

BackgroundWe report the first results of a new low-profile titanium locking plate for fixation of opening wedge high tibial osteotomy (OWHTO). Short spacer plates have been associated with a high hardware complication rate, whilst fixed angle locking plates have been associated with a high incidence of soft tissue irritation. This plate aims to achieve stable fixation whilst maintaining a low profile, allowing space for combined procedures. MethodsAll patients undergoing OWHTO with the Activmotion plate were retrospectively reviewed. Patients were allowed to progress to full weight bearing after two weeks. Radiographic assessment included the medial proximal tibial angle (MPTA) and posterior tibial slope at six weeks and then three monthly until union. All complications were recorded. ResultsThirty-seven patients with 40 OWHTOs were included in the study. The mean MPTA increased from 85.2 preoperatively to 91.9 postop. Tibial slope changed from 5.2 to 4.2°. The correction was sustained until union with no loss of correction in the MPTA (median change 0.0, 95% CI for median (−0.25, 0.4)) or tibial slope (mean increase 0.32, 95% CI (−0.02, 0.67)). ConclusionsIn this pilot study the Activmotion plate raised no safety concerns with regard to implant related adverse events or loss of initial correction. Early rehabilitation with immediate partial weight bearing was possible and all cases proceeded to osteotomy union with the exception of one case that needed to undergo bone grafting with implant retention. Premature removal of the implant was necessary in four cases due to symptomatic hardware irritation.

The outcome of anterior cruciate ligament reconstruction in skeletally immature patients with transphyseal tunnels

Objective To evaluate the clinical outcomes after transphyseal anterior cruciate ligament (ACL) reconstruction with hamstring autograft in skeletally immature patients. Methods Ten skeletally immature pubescent patients (10 knees) with a mean age of 13.4 years underwent transphyseal ACL reconstruction with hamstring autograft between May 2004 and March 2012. There were 5 males and 5 females. The average duration from injury to surgery was 5.3 months (range 1-12 months). Arthroscopy confirmed ACL rupture in ten knees. Concurrent meniscal surgery was performed in 5 knees. The surgery was conducted via arthroscopically assisted transphyseal reconstruction of the ACL with use of an autogenous quadrupled hamstring tendon graft and fixation devices that do not cross the physes. A protective knee brace was used for 3 months postoperatively with motion limits for the first 2 weeks. The follow-up duration was 6.7 years (range 3-12 years), with evaluation for the following outcomes: physical examination, namely KT-2000 measurements and functional outcome instruments (the International Knee Documentation Committee subjective knee form, the Lysholm scoring, and the Tegner knee activity scale). Radiographs were performed for asymmetrical physeal closure, growth arrest lines and leg-length measurements. Results At the latest follow-up, the mean 2000 IKDC score improved from preoperative 75.1±5.1 to 93.3±3.0, the mean Lysholm score from preoperative 66.1±8.2 to 94.8±3.6 and the mean Tegner score from 4.4±0.8 to 8.5±0.7. All these outcomes had statistically significant difference. Lachman and pivot-shift testing were weekly positive in 3 knees and negative in 7 knees. The mean range of motion of the knee was 140°. Compared with the contralateral knee, no restriction in knee range of motion of 5° or greater was observed in any patient. All patients had normal range of motion. The mean KT-2000 manual maximum side-to-side difference was 1.5±0.7 mm, while that in 3 patients was greater than 2 mm but smaller than 3 mm. No angular deformities were reported. All leg-length measurements were symmetric bilaterally on clinical examination. The mean lateral distal femoral angle was 87.4°±0.6°, and the mean medial proximal tibial angle was 88.3°±0.7°. No patients reported traumatic graft disruption or underwent revision ACL reconstruction, whereas meniscus injury occurred in 3 patients. Conclusion Transphyseal ACL reconstruction with autogenous quadrupled hamstring graft in treating skeletally immature pubescent patients yields satisfied functional outcomes without growth disturbance at a mean follow-up of 6.7 years. Key words: Anterior cruciate ligament; Wounds and injuries; Anterior cruciate ligament reconstruction; Adolescent; Growth plate

Medial Open Wedge High Tibial Osteotomy for Varus Malunited Tibial Plateau Fractures

To analyze radiologic and functional outcomes of varus malunited tibial plateau fractures managed with medial open wedge high tibial osteotomy (MOHTO). Eighteen patients with symptomatic varus malunited tibial plateau fractures with less than stage II arthritic changes managed from July 2009 to October 2013 were included. Patients with complex intra-articular step malunions and severe arthritic changes (stage III and IV) were excluded. Initially, diagnostic arthroscopy was performed followed by MOHTO stabilized with locking plate and tricortical autograft (n= 11, 61%) or a Puddu plate and allograft (n= 7, 39%). Patients were evaluated radiologically for union, medial proximal tibial angle, and tibial slope angle, and functional assessment was performed with a knee outcome survey based on activities of daily living. The mean follow-up duration was 41.7 ± 12.1months (range 25-61); all patients achieved radiologic union by a mean duration of 4.3 ± 1.2months (range 3-8). The mean medial proximal tibial angle improved from 75.3° ± 3.7° (range 70.5°-85.2°) to a postoperative angle of 83.8° ± 3.6° (range 77.5°-90.4°) (P < .001). In 12 patients, an abnormal mean anterior slope of-5.5° ± 3.0° (range-1.1° to-13°) was corrected to a postoperative posterior slope of 5.8° ± 4.4° (range-1.1° to 14.1°) (P < .001). In 6 patients, a mean posterior slope of 17.4° ± 10.5° (range 1.4°-33°) was corrected to a postoperative posterior slope of 14.08° ± 5.6° (range 7.4-21.3) (P = .214). The mean knee outcome survey scores preoperatively were 25% ± 9.68% (range 8%-48%) and postoperatively were 85% ± 11.18% (range-52% to 98%, P < .001). MOTHO for varus malunited tibial plateau fractures is safe and effective procedure that provides excellent functional outcomes, acceptable radiologic outcomes, and carries minimal complications. Level IV, therapeutic case series.

Functional joint line obliquity after kinematic total knee arthroplasty.

Kinematic total knee arthroplasty (TKA) is an emerging technique, but concerns remain around the effect of implanting the prosthesis in more anatomic orientations. Native knees show variation in joint line orientation relative to the tibial mechanical axis but the joint line remains parallel to the floor when standing. This study was undertaken to evaluate joint line obliquity relative to the floor when weight-bearing after kinematic TKA to see if a similar effect occurs. Preoperative and postoperative measurements were taken for 55 consecutive kinematically aligned TKAs, including the joint line orientation angle (JLOA), formed between the joint line and a line parallel to the floor. The mean medial proximal tibial angle (MPTA) was 3.4° varus pre-operatively (1.7° valgus to 7.9° varus, SD 2.0), and 3.0° varus postoperatively (5.5° valgus to 6.5° varus, SD 2.1). The mean postoperative JLOA was 1.0° varus with a smaller range than the MPTA (2.6° valgus to 6° varus, SD 1.9). The difference between these two measurements was significant (mean 2°, SD 2.5, p < 0.001). Relative to the mechanical axis, 33 tibial components would be considered at risk outliers, being orientated at more than 3° in varus or valgus. However, only six components were outside this range relative to the vertical, all in varus (mean 4.2°). This latter measurement may better represent how the prosthesis is functionally loaded and is similar to mechanically aligned TKAs with good survivorship. This may help explain why kinematic alignment does not lead to higher earlier failure rates that may result if similar orientations were seen with mechanically aligned TKA.

The Effect of Hinge Position on Posterior Tibial Slope in Medial Open-Wedge High Tibial Osteotomy

To evaluate whether hinge position affects the change in posterior tibial slope in medial open-wedge high tibial osteotomy (HTO). We retrospectively evaluated 19 knees from 17 patients who underwent medial open-wedge HTO by 3-dimensional computed tomography scan before and after surgery. A 3-dimensional image model was constructed by applying reverse-engineering software to the computed tomography DICOM (Digital Imaging and Communications in Medicine) files. The hinge axis (i.e., the position of the hinge compared with the anteroposterior axis on an axial view), posterior tibial slope, medial-proximal tibial angle, and gap ratio (i.e., the ratio of anterior gap to posterior gap in the opened wedge) were measured. The mean hinge axis was 4.92° ± 3.86°. Posterior tibial slope increased from 7.29° ± 2.56° preoperatively to 10.48° ± 3.01° postoperatively (P= .001). The mean medial-proximal tibial angle was 85.96° ± 1.97° preoperatively and 93.13° ± 3.17° postoperatively (P= .001). The mean gap ratio was 62.48% ± 7.26%. Linear regression analysis determined that the hinge axis (P= .0001) was a significant factor changing posterior tibial slope. Hinge position affected the change in posterior tibial slope in medial open-wedge HTO; in particular, a posterolateral hinge position led to an increase in posterior tibial slope. Level IV, therapeutic study.

Are Navigation Systems Accurate Enough to Predict the Correction Angle During High Tibial Osteotomy?

Background: Unpredicted overcorrection of the mechanical axis can occur during navigation-assisted high tibial osteotomy (HTO). It is not clear whether the erroneous overcorrection stems from the navigation system itself or from other causes. Purpose: To evaluate the accuracy of the navigation system in HTO by comparing the change in the femorotibial angle provided by the navigation system with the bony correction angle of the proximal tibia on 3-dimensional computed tomography (3D CT) and with the change in mechanical femorotibial alignment on standing whole-leg radiographs. Study Design: Cohort study (diagnosis); Level of evidence, 2. Methods: A total of 16 knees underwent navigation-assisted HTO, and their alignment data were obtained before and after correction. For comparison, preoperative and follow-up standing whole-leg anteroposterior radiographs, lateral knee radiographs, and preoperative and postoperative 3D CT scans were taken. The medial proximal tibial angle (MPTA), posterior tibial slope, and mechanical femorotibial angle (mFTA) were measured in these images, and the 3 coronal and 3 sagittal correction angles were compared with each other. Results: In the coronal plane, the mean correction angle of the navigation system was 9.3° ± 2.0° valgus (range, 6°-13°), and the mean MPTA on 3D CT increased 9.7° ± 2.0° (range, 6.7°-13.8°) after correction. The mean correction angle of the mFTA on standing radiographs was 11.9° ± 3.2° valgus (range, 6.9°-16.5°). There was no statistical significance between the navigation system and 3D CT (P = .187), but there was a statistically significant difference between the navigation system and standing radiographs (P = .001). The results of the correction angle in the sagittal plane were similar to those in the coronal plane. Conclusion: The correction of the femorotibial angle by the navigation system was not different from the bony correction angle on 3D CT. There was a discrepancy between the correction angle of the navigation system and that of the standing radiograph. Clinical Significance: Surgeons must be cautious about the tension of soft tissue, even when using the navigation system during HTO.

Treatment of Schatzker Type V and VI Tibial Plateau Fractures Using a Midline Longitudinal Incision and Dual Plating

PurposeThe purpose of this study was to evaluate the results of the treatment of Schatzker type V and VI tibial plateau fractures using a midline longitudinal incision and dual-plate fixation.Materials and MethodsTen patients with Schatzker type V and VI tibial plateau fractures treated with a midline longitudinal incision and dual plating were analyzed. The patients were followed for a minimum of one year. Clinical outcomes were evaluated using range of motion, visual analogue scale (VAS) and Knee Society Score. Radiological outcomes were evaluated using the bony union time, medial proximal tibial angle (MPTA) and posterior proximal tibial angle (PPTA).ResultsThe mean VAS score was 2.2 points, and the mean Knee Society function score was 85 points at the final follow-up. The mean flexion contracture was 2.5° and the mean further flexion was 125°. It took an average of 4 months until bony union occurred. The mean MPTA and PPTA were 90.5° and 4.4°, respectively. There was one case of delayed wound healing, but no other complications were observed.ConclusionsThe treatment of Schatzker type V and VI tibial plateau fractures with a midline longitudinal incision and dual-plate fixation resulted in satisfactory clinical and radiological outcomes. This can be an option when treating Schatzker type V and VI tibial plateau fractures.

Medial Open Wedge High Tibial Osteotomy

Background High tibial osteotomy can affect the posterior tibial slope in the sagittal plane because of the triangular configuration of the proximal tibia. However, the effect of the location of cortical hinge on posterior tibial slope has not been previously described. Hypothesis Posterolateral location of the cortical hinge will increase posterior tibial slope after medial open wedge osteotomy, and lateral location of the cortical hinge will not affect the change of the posterior tibial slope. Study Design Controlled laboratory study. Methods We performed incomplete valgus open wedge osteotomy on 12 paired knees of 6 fresh-frozen human cadavers (age, 63.4 ± 7.5 years) using an OrthoPilot navigation system. The left and right legs of each specimen were randomly assigned to a posterolateral (group A) or a lateral (group B) cortical hinge group. Changes in mean medial proximal tibial angle, posterior tibial slope, and opening wedge angle were measured and compared after surgery. Results In group A, mean medial proximal tibial angle changed from 84.37° ± 2.8° to 93.48° ± 3.06° (P = .028); mean posterior tibial slope increased significantly from 8.71° ± 0.81° to 12.16° ± 0.84° (P = .031); and mean wedge angle was 1.92° ± 0.46°. In group B, mean medial proximal tibial angle changed from 82.98° ± 2.53° to 90.89° ± 3.25° (P = .027); mean posterior tibial slope changed from 9.19° ± 1.11° to 9.78° ± 1.27° (P = .029); and mean wedge angle was 7.25° ± 0.72°. Conclusion The location of the intact cortical hinge affects the posterior tibia slope. During medial open wedge osteotomy, the change of posterior tibial slope was larger in the posterolateral than in the lateral cortical hinge group. Clinical Relevance To prevent the unintentional increase of the posterior tibial slope, special attention should be paid to locate the intact cortical hinge on the lateral, not the posterolateral, side of the tibia.

Lower Limb Alignment in Children

A full-length standing anteroposterior radiograph of the entire lower extremity has become the standard imaging modality for assessing lower limb alignment. Although reference values of frontal plane deformity parameters based on adult subjects have been established, such values may not be applicable to the pediatric population. The purpose of our study was to establish the reference values of frontal plane alignment and joint orientation angles in children based on a standing full-length radiograph. A database at a single institution was searched for patients who were aged between 1 and 18 years at the time of undergoing a standing full-length radiograph of the lower extremities. Radiographic analysis of lower extremities without any abnormalities was performed by a single observer. Mechanical axis deviation, lateral distal femoral angle (LDFA), medial proximal tibial angle (MPTA), tibiofemoral angle, joint line convergence angle, and mechanical axis station were calculated at yearly intervals. The data were summarized using descriptive statistics, and simple regression analysis was performed to determine the relationship between the patients' age and the magnitude of LDFA and MPTA. A total of 354 unaffected lower extremities in 253 children were analyzed. Between the ages of 1 and 2 years, the tendency for varus alignment of the lower limb was related to the varus orientation of the distal femur with a mean LDFA of 95 degrees (95% confidence interval [CI], 93-97 degrees). By the age of 3 years, the limb alignment changed to valgus related to a combination of decreasing varus orientation of the distal femur and a mild increase in valgus orientation of the proximal tibia with the mean MPTA changing from 89 degrees (95% CI, 88-90 degrees) to 91 degrees (95% CI, 90-92 degrees). After the age of 7 years, all joint orientation angles were noted to be within the range of reference values that are available for the adult population. Despite changes in limb alignment with growth, the mean mechanical axis of the lower extremity remained within the central half of the knee joint in children older than 1 year of age. The change in alignment of the lower limb from 1 to 4 years of life from varus to valgus is primarily related to a progressive decrease in varus orientation of the distal femur. In children younger than 7 years old, age-specific reference values for joint orientation angles of the lower extremity should be used instead of values derived from adult subjects.

Femoral Deformity in Tibia Vara

Previous studies have suggested that compensatory valgus deformity of the femur is common in patients with tibia vara, or Blount disease. The availability and routine use of standing long-cassette radiographs of the lower extremities to assess angular deformities has allowed quantitative evaluation of this hypothesis. The cases of all patients with tibia vara, two years of age or older, seen at our institution prior to treatment, over a thirteen-year period, were reviewed. Seventy-three patients with a total of 109 involved lower limbs were identified and were classified as having either infantile tibia vara (thirty-seven patients with fifty-six involved limbs) or late-onset tibia vara (thirty-six patients with fifty-three involved limbs). Standardized standing radiographs of the lower extremity were examined to assess the deformity at the distal part of the femur and the proximal part of the tibia by measuring the lateral distal femoral angle and the medial proximal tibial angle. The distal part of the femur in the children with infantile tibia vara either was normal or had mild varus deformity, with a mean lateral distal femoral angle of 97 degrees (range, 82 degrees to 129 degrees). The mean medial proximal tibial angle in these children was 72 degrees (range, 32 degrees to 84 degrees). Older children with infantile tibia vara were noted to have little distal femoral deformity, with no more than 4 degrees of valgus compared with either normal values or the contralateral, normal limb. Children with late-onset tibia vara had a mean lateral distal femoral angle of 93 degrees (range, 82 degrees to 110 degrees) and a mean medial proximal tibial angle of 73 degrees (range, 52 degrees to 84 degrees). On the average, the varus deformity of the distal part of the femur constituted 30% (6 degrees of 20 degrees) of the genu varum deformity in these patients. Patients with infantile tibia vara most commonly had normal alignment of the distal parts of the femora; substantial valgus deformity was not observed. Distal femoral varus constituted a substantial portion of the genu varum in children with late-onset disease. When correction of late-onset tibia vara is planned, the surgeon should be aware of the possibility that distal femoral varus is a substantial component of the deformity.

Outcome of Hemiepiphyseal Stapling for Late-Onset Tibia Vara

The results of hemiepiphysiodesis for the treatment of late-onset tibia vara have been reported to be favorable, but the technique requires careful timing and an accurate estimation of skeletal age. Hemiepiphyseal stapling does not require a careful estimation of skeletal age, and it has been reported to yield good results with low morbidity. However, we are not aware of any study evaluating the intermediate-term radiographic results or complications of this procedure. Twenty-six patients with thirty-three extremities with late-onset tibia vara were treated with proximal tibial hemiepiphyseal stapling. Fourteen extremities had substantial concomitant distal femoral varus and also had hemiepiphyseal stapling of the distal part of the femur. Eighteen patients (twenty-three involved extremities) had juvenileonset tibia vara and eight patients (ten involved extremities) had adolescent-onset tibia vara. The mean age at the time of stapling was 11.8 years. The mean duration of follow-up was 3.8 years. We reviewed standardized standing radiographs to determine the mechanical axis deviation, the medial proximal tibial angle, the lateral distal femoral angle, and the zone of the knee through which the mechanical axis passed. The mean mechanical axis deviation improved from 58 mm (range, 27 to 157 mm) preoperatively to 22 mm (range, -33 to 117 mm) at the time of the last follow-up, and the mean medial proximal tibial angle improved from 77 degrees (range, 50 degrees to 85 degrees ) to 85 degrees (range, 48 degrees to 95 degrees ). In the fourteen lower extremities in which distal femoral hemiepiphyseal stapling was performed, the mean lateral distal femoral angle improved from 96 degrees (range, 92 degrees to 100 degrees ) to 86 degrees (range, 79 degrees to 97 degrees ). At the time of the final follow-up, seven extremities were considered to be in moderate varus; four, in mild varus; twenty, in normal alignment; and two, in valgus. No differences in radiographic outcome were noted between the juvenile and adolescent forms of tibia vara. Only one of the four extremities with severe preoperative varus was corrected to normal alignment; the remaining three were left with moderate varus. Hemiepiphyseal stapling of the lateral aspect of the proximal tibial physis and, as needed, the lateral aspect of the distal femoral physis is safe and effective in children with late-onset tibia vara if the physes are sufficiently open and the varus deformity is mild to moderate. Hemiepiphyseal stapling is particularly effective in patients who are ten years of age or younger. Therapeutic Level IV.

OUTCOME OF HEMIEPIPHYSEAL STAPLING FOR LATE-ONSET TIBIA VARA

Background: The results of hemiepiphysiodesis for the treatment of late-onset tibia vara have been reported to be favorable, but the technique requires careful timing and an accurate estimation of skeletal age. Hemiepiphyseal stapling does not require a careful estimation of skeletal age, and it has been reported to yield good results with low morbidity. However, we are not aware of any study evaluating the intermediate-term radiographic results or complications of this procedure. Methods: Twenty-six patients with thirty-three extremities with late-onset tibia vara were treated with proximal tibial hemiepiphyseal stapling. Fourteen extremities had substantial concomitant distal femoral varus and also had hemiepiphyseal stapling of the distal part of the femur. Eighteen patients (twenty-three involved extremities) had juvenileonset tibia vara and eight patients (ten involved extremities) had adolescent-onset tibia vara. The mean age at the time of stapling was 11.8 years. The mean duration of follow-up was 3.8 years. We reviewed standardized standing radiographs to determine the mechanical axis deviation, the medial proximal tibial angle, the lateral distal femoral angle, and the zone of the knee through which the mechanical axis passed. Results: The mean mechanical axis deviation improved from 58 mm (range, 27 to 157 mm) preoperatively to 22 mm (range, -33 to 117 mm) at the time of the last follow-up, and the mean medial proximal tibial angle improved from 77° (range, 50° to 85°) to 85° (range, 48° to 95°). In the fourteen lower extremities in which distal femoral hemiepiphyseal stapling was performed, the mean lateral distal femoral angle improved from 96° (range, 92° to 100°) to 86° (range, 79° to 97°). At the time of the final follow-up, seven extremities were considered to be in moderate varus; four, in mild varus; twenty, in normal alignment; and two, in valgus. No differences in radiographic outcome were noted between the juvenile and adolescent forms of tibia vara. Only one of the four extremities with severe preoperative varus was corrected to normal alignment; the remaining three were left with moderate varus. Conclusions: Hemiepiphyseal stapling of the lateral aspect of the proximal tibial physis and, as needed, the lateral aspect of the distal femoral physis is safe and effective in children with late-onset tibia vara if the physes are sufficiently open and the varus deformity is mild to moderate. Hemiepiphyseal stapling is particularly effective in patients who are ten years of age or younger. Level of Evidence: Therapeutic Level IV. See Instructions to Authors for a complete description of levels of evidence.