Femoral Varus Research Articles

Early Bony Hip Reconstructive Surgery for Hip Subluxation in Children With Severe Cerebral Palsy.

Hip subluxation occurs frequently in children with severe cerebral palsy. This retrospective study examined the effects of age and type of bony surgery on radiographic outcomes of children with severe cerebral palsy who were treated for hip subluxation. The study included nonambulatory children with cerebral palsy undergoing bony hip reconstructive surgery consisting of proximal femoral varus derotational osteotomy (VDRO) alone or combined with pelvic osteotomy. The migration index was recorded for preoperative, postoperative, and final follow-up (minimum 2 years) radiographs. Failure was defined as subsequent bony hip reconstructive surgery or final follow-up migration index greater than 50%. Seventy-seven hips in 40 patients younger than 6 years (55 VDRO alone, 22 combined) and 73 hips in 43 patients older than 6 years (27 VDRO alone, 46 combined) met inclusion criteria. For VDRO alone, the failure rate for patients younger than 6 years (33%) was significantly higher than for patients older than 6 years (7%). For combined procedures, failure rates between younger (0%) and older groups (9%) were not significantly different. Patients younger than 6 years undergoing combined procedures started with a significantly worse migration index than patients undergoing VDRO alone, 72% vs 46%, yet had significantly better final migration indices of 13% vs 31%, respectively. For surgeons performing bony reconstructive surgery to treat hip subluxation in younger children with severe cerebral palsy who are nonambulatory, the findings of this study support the use of combined VDRO and pelvic osteotomy. [Orthopedics. 2021;44(2):e294-e300.].

Biomechanical analysis of canine medial patellar luxation with femoral varus deformity using a computer model

BackgroundFemoral varus deformities complicating the realignment of the quadriceps muscles are frequently associated with medial patellar luxation (MPL) in dogs. Therefore, distal femoral osteotomy (DFO) is recommended in dogs affected with severe MPL and a distal femoral varus deformity. The presence of an anatomic lateral distal femoral angle (aLDFA) of ≥ 102° has been anecdotally recommended as an indication for performing corrective DFO in large-breed dogs. However, the effect of a femoral varus deformity on MPL has not been scientifically evaluated. We aimed to evaluate the influence of a femoral varus deformity on MPL using a finite element method based computer model.Three-dimensionally reconstructed computed tomographic images of a normal femur from a Beagle dog were deformed using meshing software to create distal varus deformities. A total of thirteen aLDFAs, including 95°, 98° and 100°–110°, were simulated. The patellar positions and reaction force between the patella and trochlear grooves were calculated for all finite element models under constant rectus femoris muscle activation.ResultsThe patella was displaced medially from the trochlear groove at an aLDFA of ≥103°. With an aLDFA of 103° to 110°, the reaction force was equal to zero and then decreased to negative values during the simulation, while other models with aLDFAs of 95°, 98°, and 100°-102° had positive reaction force values. The patella began to luxate at 24.90 seconds (sec) with an aLDFA of 103°, 19.80 sec with an aLDFA of 104°, 21.40 sec with an aLDFA of 105°, 20.10 sec with an aLDFA of 106°, 18.60 sec with an aLDFA of 107°, 15.30 sec with an aLDFA of 108°, 16.60 sec with an aLDFA of 109°, and 11.90 sec with an aLDFA of 110°.ConclusionSevere distal femoral varus with an aLDFA of ≥103° caused MPL when other anatomical factors were controlled. Thissimplified computer model provides complementary information to anecdotal cutoffs for DFO, hence it should be applied to clinical patients with caution.

Return to Work After Distal Femoral Varus Osteotomy.

Background:Distal femoral varus osteotomy (DFVO) is a well-described procedure to address valgus deformity of the knee. There is a paucity of information available regarding patients’ ability to return to work (RTW) after DFVO.Purpose:To report the objective findings for RTW rates and times for patients receiving a DFVO for lateral compartment osteoarthritis secondary to valgus deformity of the knee.Study Design:Cohort study; Level of evidence, 3.Methods:This was a retrospective study of patients who received a lateral-wedge opening DFVO. Patients must have worked within 3 years before their operation to be included for analysis. Patients were contacted at a minimum of 2 years postoperatively for interview and questionnaire evaluation, including a subjective work questionnaire, visual analog scale (VAS) for pain, Single Assessment Numerical Evaluation (SANE), and a satisfaction questionnaire.Results:Overall, 32 patients were contacted at a mean follow-up of 7.1 ± 4.1 years (range, 2.2-13.3 years). The mean ± SD age at the time of surgery was 30.8 ± 8.8 years (range, 17.2-46.5 years), and 65.6% of patients were female. Eleven patients (34.4%) received a concomitant meniscal allograft transplant, and 12 (37.5%) received a cartilage grafting procedure. The average VAS pain score decreased significantly from 6.1 preoperatively to 3.2 postoperatively (P = .03). All patients were able to RTW, at a mean time of 6.0 ± 13.2 months postoperatively (range, 0-72 months). When stratified by work intensity, the average time to return was 13.8, 3.1, 2.7, and 2.9 months for high, moderate, light, and sedentary occupations, respectively. There was no significant difference between these RTW times (P = .16), although this analysis may have been limited by the small sample size. Four patients whose work was classified as heavy work (50%) and 3 whose work was classified as moderate work (18.8%) either switched jobs or kept the same job with lighter physical duties as a result of their procedures.Conclusion:In a young and active population, DFVO for valgus deformity reliably afforded the ability to RTW within a relatively short time for patients with sedentary, light, and moderate occupational demands. However, patients with moderate- to high-intensity occupational demands may be unable to RTW at their preoperative level.

Orthopaedic manifestations of glutaric acidemia Type 1.

PurposeGlutaric acidemia type 1 (GA1), a rare hereditary metabolic disease caused by biallelic mutations of GCDH, can result in acute or insidious striatal degeneration within the first few years of life. We reviewed the orthopaedic sequelae and management of 114 neurologically injured patients with a confirmed molecular diagnosis of GA1.MethodsWe performed a retrospective chart review spanning 28 years identifying 114 GA1 patients, most from the Old Order Amish population of Lancaster County, Pennsylvania, who were homozygous for a pathogenic founder variant of GCDH (c.1262C>T). We collected demographics, medical comorbidities, muscle tone patterns, Gross Motor Function Classification System level, gastrostomy tube status, seizure history, inpatient events, orthopaedic diagnoses and operative characteristics.ResultsOver an average follow-up of 4.7 ± 3.4 years, 24 (21%) of 114 patients had musculoskeletal problems requiring orthopaedic consultation. Scoliosis (n = 14), hip dislocation (n = 8/15 hips), hip subluxation (n = 2/three hips), and windswept hip deformity (n = 2) in the spine and hip joint were most common. In total, 35 orthopaedic surgeries were performed in 17 (71%) patients. The most common primary operations were one-stage procedures with proximal femoral varus derotation osteotomy and/or pelvic osteotomy (n = 8/14 hips) for subluxation or dislocation. In all, 11 patients had posterior spinal fusion for severe scoliosis. With the recommended metabolic management, there were no disease-specific complications in this cohort.ConclusionsChildren with GA1 who have static striatal lesions are at risk for musculoskeletal complications, especially scoliosis and hip dislocation, and appropriate operative management requires consultation with a metabolic specialist with specific considerations for fluid management and nutrition.Level of EvidenceIV

Successful treatment of a habitual patellar dislocation after a total knee arthroplasty with a closing-wedge distal femoral varus osteotomy and medial patello-femoral ligament reconstruction

A 68-year-old female suffering from habitual patellar dislocations following a mal-positioned total knee arthroplasty (TKA) was successfully treated with a biplanar closed wedge distal femoral osteotomy (CWDFO) and medial patello-femoral ligament (MPFL) reconstruction. To the best of our knowledge, no such case has been previously described. Our experience with this case suggests that treatment for a patella dislocation following valgus mal-positioning of TKA should be considered positively.Level of evidenceV

How to determine the type of femoral osteotomy in the management of developmental dysplasia of the hip: a prospective case series

Background: Developmental dysplasia of the hip (DDH) is a disease that presents with multiple abnormalities, varying from mild dysplasia to frank dislocation. Management of DDH is determined by the patient’s age, and the best results are gained if treatment is initiated at an early age. Methods: This prospective case series study included 40 hips (37 patients) with primary DDH, that had open reduction and capsulorrhaphy. According to the measured caput-collum-diaphyseal (CCD) angle, the patients were classified into two groups. Group 1 was assigned femoral derotation osteotomy (FDO) and included 20 hips (19 patients) with normal CCD angle ≤140 degrees. Group 2 was assigned femoral varus derotation osteotomy (VDO) and included 20 hips (18 patients) with coxa valga and increased CCD angle >140 degrees. All patients were followed a minimum of 2 yr with a mean of 3.96±1.45 yr (range 2 to 7 yr). Results: The mean postoperative Sharp’s acetabular index was 17.65±3.69 degrees in group 1 as compared to 20.85±6.64 degrees in group 2. There was a significant difference between both groups in limb-length discrepancy, persistent Trendelenburg sign, and residual coxa vara. Conclusions: Femoral shortening should be performed in cases where tight reduction is achieved to avoid pressure on the femoral head and development of avascular necrosis (AVN). Femoral derotational osteotomy was usually required with femoral shortening because most of the cases had excessive femoral neck anteversion. Evaluation of the CCD angle was done preoperatively and intraoperatively to determine the need for adding varus. If the CCD angle was less than 140 degrees, additional varization was deemed unnecessary. Level of Evidence: Level III

Fixation Stability and Stiffness of Two Implant Systems for Proximal Femoral Varization Osteotomy

Proximal femoral varization osteotomy is a well-established surgical procedure in children with severe hip problems. This study aimed to evaluate the fixation stability and stiffness of two new implant systems. A biomechanical testing model was created with a total of 12 synthetic femora. Proximal femoral varization osteotomy was performed in every femur, and the synthetic femora were fixed with two different implant systems (PediLoc Locking Proximal Femur Plate System versus PediLoc Locking Cannulated Blade Plate System; OrthoPediatrics, Warsaw, IN, USA). The average torsional stiffness of the locking plate group was higher than for the cannulated blade plate group. Differences in internal and external rotations were seen between the two groups, but they were not significant. Using the tested implants in severe osteoporotic bones might show other results. Therefore, it might be helpful to use the locking plate system in osteoporotic bones and in cases of revision operations where stability is of critical focus.

Distal femoral phenotypes in Asian varus osteoarthritic knees.

There has been a general consensus regarding the varus phenotype of the proximal tibia in osteoarthritic patients with varus knee alignment of the whole limb. However, a valgus phenotype of the distal femur may occur in osteoarthritic patients with varus knee alignment. This study evaluated the distal femur phenotype in varus osteoarthritic knees. This study included 128 patients who underwent primary total knee arthroplasty (TKA) by computer-assisted navigation for primary medial osteoarthrosis with varus knee alignment. The hip-knee-ankle (HKA) angle, medial proximal tibial angle (MPTA), lateral distal femoral angle (LDFA), and joint line convergence angle (JLCA) were measured on which radiographs preoperatively. The radiographic parameters were compared between groups with HKA angle varus ≥ 10° and < 10°. The MPTA was significantly lower (4°) in the HKA angle varus ≥ 10° group than in the < 10° group (82.13° vs. 86.13° P = 0.001), but the LDFA did not differ significantly between the groups (89.81° vs. 89.19° P = 0.181). Regarding the JLCA, the varus ≥ 10° group showed a 1.3° greater lateral widening than the varus < 10° group (4.87 vs. 3.56, P = 0.002). The MPTA was the only independent predictor of the MA of the lower limb (β = - 0.353, P < 0.001). One-third of varus osteoarthritic knees had a distal femur valgus phenotype. Varus knee alignment was mainly affected by proximal tibia varus rather than by distal femur varus. Level III, consecutive case series.

The Clinical Outcome of Simultaneous Lateral Closed- Wedge Distal Femoral Osteotomy and Anterior Cruciate Ligament Reconstruction in the ACL-deficient Knees with Symptomatic Femoral Varus Deformity.

Nowadays combined high tibial osteotomy and ACL reconstruction is accepted as a safe and effective surgery for patients with symptomatic varus osteoarthritis and anterior knee instability; however, the source of varus deformity is sometimes the femoral bone. No studies have reported concomitant ACL reconstruction and distal femoral osteotomy in ACL-deficient knees with femoral varus deformity and medial osteoarthritis till now. This prospective study presents the technique and clinical outcome of a consecutive series of simultaneous lateral closed-wedge distal femoral osteotomy and ACL reconstruction. Nineteen patients with confirmed ACL rupture and femoral varus deformity (mechanical lateral distal femoral angle ≥ 93°) associated with medial osteoarthritis (± lateral thrust) were included the study. The patients underwent simultaneous lateral closed-wedge distal femoral osteotomy and ACL reconstruction. At the end of one year follow up, the final range of motion and stability of the knees and the last alignment of extremities were recorded. Surgical outcomes were assessed on 2000 IKDS subjective scores and KOOS subscales. The mean preoperative varus knee was 10.6° (±2.2°) mostly from the femoral side. The mean union time was 3.2 (±0.4) months. Regarding the radiological evaluation, the alignment of extremity and mLDFA were corrected significantly compared to the pre-operative findings. At the end of one year follow up, all patients were free of knee instability. Subjective assessment based on questionnaires showed a significant improvement in all aspects of knee function after surgery, however there was no considerable change in the knees range of motion. Simultaneous lateral closed- wedge distal femoral osteotomy and ACL reconstruction is a valuable procedure in femoral varus knees with medial osteoarthritis and anterior knee instability. After one year follow up all aspects of knee function were improved without serious complications.

Femoral Remodeling after Proximal Femoral Varus Osteotomy in Children with Cerebral Palsy

Purpose: Varus osteotomy of the proximal femur is a commonly used procedure to improve hip congruity and correct the often valgus deformity in children with cerebral palsy (CP). Femoral remodeling can occur over time causing a relapse of coxa valga. The degree to which this remodeling occurs and possible risk factors remain controversial. The purpose of this study is to 1) establish the degree of which femoral remodeling occurs, and 2) to determine the …

Femoral Remodeling after Proximal Femoral Varus Osteotomy in Children with Cerebral Palsy

Femoral Remodeling after Proximal Femoral Varus Osteotomy in Children with Cerebral Palsy

Prognostic Factors Influencing Outcomes of High Tibial Osteotomy in The Varus Knee: The Role of The Deformity

Objectives:High Tibial Osteotomy (HTO) is widely performed to treat early arthiritis in the varus knee. The aim of this prospective study is to evaluate different prognostic factors affecting the outcomes of HTO and, with special attention to the role of the site of deformity.Methods:231 Opening Wedge HTO (OWHTO) were performed in 202 patients and included in the study. Inclusion criteria were: 1) age > 18 years, 2) no major associated procedures (i.e. ACL reconstruction, major cartilage procedure, 3) only OWHTO, 4) pre-operative complete clinical and radiological evaluation available. Patients were evaluated with (1) the Knee Society score (KSS), (2) the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score, (3) another self-evaluation scale, (4) long-leg radiographs, and (5) plain radiographs. On the x-ray different angles were evaluated, including Join Line Congruence Angle. Furthermore, the location of deformity was established. Three main outcomes were identified: Indication to Total Knee Arthroplasty (TKA), KSS poor or fair and WOMAC < 76 points), and different prognostic factors were identified (Fig. 1). All the variables were firstly tested in a single regression model to evaluate the association with each outcome. All the variables with p<0.1 were re-tested in a multiple regression model.Results:32 patients were lost to follow-up and 31 patients did not meet the inclusion criteria, leaving 139 patients (156 OWHTOs) for the study. The average age was 52.9 ± 9.6 years, and the average follow-up was 97.7 ± 42.8 months. Post-operatively there was a significant improvement in both the KSS and WOMAC score compared to the pre-operative period (p<0.0001). The only variable related to TKA indication was a pre-operative JLCA ≥5° (OR=24.3, p=0.0483). Conversely, different variables were related to a worse KSS, including pre-operative BMI >30 Kg/m2 (OR=78.9, p=0.0028), pre-operative ROM <120° of flexion (OR=40.8, p=0.0421), pre-operative mLDFA ≥91° (OR=36,6,p=0.0401) and femoral pre-operative CORA ≥3° of varus (OR=39,9 p=0.0269). Furthermore, a pre-operative BMI >30 Kg/m2 (OR=29,5, p=0.0314) was associated to a worse WOMAC score. Conversely, patients with a pre-operative mMPTA ≤84° had lower risk to obtain a worse KSS oe WOMAC score (respectively OR= 0,2 p=0.0364 and OR=0,3 p=0.0071). The cumulative survivorship was calculated with the Kaplan-Meier method, and it resulted equal to 98.6% at 5 years and decreased to 85.5% at 10 years.Conclusion:OWHTO is a good treatment for early arthritis in the varus knee if the correct indications are applied. The outcomes can be considered good, with 85% of 10-year survivorship. It is mandatory to correctly address the location of the deformity, because the presence of a femoral varus deformity is related to worse outcomes. Similarly, presence of a pre-operative JLCA ≥5° is the only factor associated to TKA indication.Table 1.Pre-OperativeIntra-OperativeBMIAssociated proceduresAge (≥56 years)Cartilage damageGender Educational status Post-Operative Amount of deformityWeight bearing line (%)ROMI (Range of motion)JLCAKnee Society scoremLDTA (mechanical lateral distal tibial angle)Function score WOMAC scale Amount of medial arthritis Presence of lateral arthritis mLDFA (mechanical lateral distal femoral angle) mMPTA (mechanical medial proximal tibial angle) JLCA (Joint Line Congruence Angle) Femoral CORA (center of rotation and angulation)

Acetabular Dysplasia in Children with Cerebral Palsy: Can Isolated Femoral Varus Osteotomies Help?

Purpose: The remodeling potential of the dysplastic acetabulum in children with neuromuscular disorders is not clear and how to address residual acetabular dysplasia after femoral osteotomy in children with cerebral palsy remains unknown. The purpose of this study is to 1) quantify acetabular remodeling in patients with CP who received a femoral osteotomy without an acetabular osteotomy and 2) to determine the impact of age and Gross Motor Function …

Acetabular Dysplasia in Children with Cerebral Palsy: Can Isolated Femoral Varus Osteotomies Help?

Acetabular Dysplasia in Children with Cerebral Palsy: Can Isolated Femoral Varus Osteotomies Help?

Clinical Results of Distal Femoral Osteotomy for Treatment of Grade 4 Medial Patella Luxation with Concurrent Distal Femoral Varus in Small Breeds Dogs: 13 Cases

Clinical Results of Distal Femoral Osteotomy for Treatment of Grade 4 Medial Patella Luxation with Concurrent Distal Femoral Varus in Small Breeds Dogs: 13 Cases

Segmental Femoral Ostectomy for the Reconstruction of Femoropatellar Joint in Dogs with Grade IV Medial Patellar Luxation.

The aim of this study was to describe a new surgical method of segmental femoral ostectomy for the reconstruction of the femoropatellar joint (FPJ) in dogs with medial patellar luxation (MPL) grade IV. The medical records of six dogs that underwent segmental femoral ostectomy to reconstruct the FPJ for MPL grade IV were retrospectively reviewed. The data included breed, age, body weight, comorbidities, history of orthopaedic abnormalities, pre- and postoperative radiographic findings, morphological indicators measured on three-dimensional computed tomographic multiplanar reconstruction images, surgical methods and postoperative complications. Eleven hindlimbs with MPL grade IV in six dogs underwent segmental femoral ostectomy to reconstruct the FPJ with the four basic surgical procedures. Six stifle joints with femoral varus deformity were treated by closing wedge ostectomy and segmental ostectomy, while five stifle joints were treated by segmental ostectomy alone. The mean resected femoral length was 11.7 mm. The mean resected femoral length relative to the preoperative femoral length was 14.3%. The stability and congruity of the FPJ was markedly improved, with an increased range of motion in all dogs compared with their preoperative status. Segmental femoral ostectomy was a useful treatment method for MPL grade IV with shortened quadriceps muscle length relative to the femoral length. Reconstruction of the FPJ is important for recovery of limb function.

Medial closing-wedge distal femoral varus osteotomy: Symptoms and functional impact in cases of associated patellofemoral osteoarthritis. A two-year follow-up prospective pilot study

PurposeTo date, indications for distal femoral varus osteotomy (FVO) in cases of associated patellofemoral osteoarthritis (PFO) have yet to be clarified. The purpose of this prospective study is to assess the short-term symptoms, functional and radiological impact of a medial closing-wedge femoral varus osteotomy on the patellofemoral joint in patients with valgus deformities who are afflicted with lateral tibiofemoral osteoarthritis (LTFO) associated with PFO. MethodsFourteen patients (15 knees) received a medial closing-wedge femoral varus osteotomy. The functional impact of an FVO on the patellofemoral joint was assessed based on the KOOS-PF (Knee Injury and Osteoarthritis Outcome Score-Patellofemoral Subscale), the Kujala score and the patellofemoral symptoms. Realignment of the patella was measured by the Merchant's patellofemoral congruence angle. The pre- and post-operative symptoms and functional scores were compiled prospectively and compared two years after the surgery. ResultsThe Kujala patellofemoral functional scores and the KOOS-PF showed considerable improvement with a differential of +37.5 points ± 20.4 and +42.7 points ± 19.3 (p < .01) respectively. The average Merchant's congruence angle went from 8.8° laterally to 3.6° medially, resulting in medialization of the patella, with a significant difference (p < .01). Based on the specific clinical analysis of the patellar joint, preoperative J-sign was identified in 26.7% of patients (n = 4) and was not found during postoperative examination (p = .1). Preoperative apprehension test was identified in 33.3% of patients (n = 5) against 13.3% (n = 2) after surgery (p = .39). Preoperative pain extension test was identified in 40% of patients (n = 6) against 20% during postoperative clinical analysis (p = .43). DiscussionAlthough the threshold of significance for patellofemoral symptoms was not reached, the medial closing-wedge femoral varus osteotomy induces a significant medialization of the patella (Merchant's congruence angle) and improves short-term functional results even with co-existing patellofemoral osteoarthritis. Due to the lack of specificity of the patellofemoral scores, patellofemoral osteoarthritis improvement is difficult to determine on its own, but does not represent a contraindication to FVO. Level of evidenceIII. Prospective clinical study.

Safety and efficacy of tranexamic acid in children with cerebral palsy undergoing femoral varus derotational osteotomy: a double cohort study.

The safety and efficacy of tranexamic acid (TXA) in reducing blood loss after total joint arthroplasty and spinal fusion surgery has been well documented. However, little data exist regarding the effectiveness of intraoperative TXA in children with cerebral palsy (CP). The aim of this double cohort study is to investigate the safety and efficacy of intraoperative TXA in reducing blood loss and transfusion requirements for children with CP undergoing a proximal unilateral or bilateral femoral varus derotational osteotomy (VDRO). A retrospective review was performed of all paediatric theatre lists between May 2012 and January 2019 for all paediatric (< 16years old) CP patients who underwent unilateral or bilateral VDRO combined with soft tissue release at our institution. Fifty-one patients were included in our study further subdivided into two individual groups, unilateral and bilateral VDRO. No statistically significant differences were found in demographics such as age, weight, ASA, GMFCS and antiepileptic medication between the groups. However, there were significant statistically differences in TBL and transfusion rates between the groups that received TXA and those that did not, both in unilateral [241ml (TXA) vs. 369ml (non-TXA)] and bilateral [287ml (TXA) vs. 467ml (non-TXA)] operations. TXA successfully reduced TBL (in both TXA subgroups) and the transfusion rates without associated complications. TXA's safety and efficacy should be explored further in adequately powered randomized controlled trials.

In vivo kinematic analysis of the osteoarthritis knees which have large joint convergence angle during gait activities

Purpose: The varus knee osteoarthritis (OA) is a pathological condition that results from the varus deformity of the lower extremities caused by a narrowing of the medial joint space due to meniscus injury or cartilage damage. As an operation for the varus deformity knee, osteotomy around the knee joint is attracting attention especially from the viewpoint of joint preserving surgery. However, there are many reports on changes in alignment before and after osteotomy, but there are few reports on dynamic analysis before and after surgery on living knees. In some cases of varus deformity, some cases are accompanied by lateral thrust, but the dynamics are still unclear. In this study, we aimed to clarify the dynamics of lateral thrust during walking in a varus deformity knee with a large joint line convergence angle. Methods: The subjects were 6 knees. All patients visited our hospital and were scheduled for osteotomy procedures. The patient characteristics were as follows: all cases were female, mean age was 64.8 ± 7.4 years, mean height was 152.4 ± 4.0 cm, mean body weight was 60.4 ± 9.0 kg, and mean BMI was 26.0 ± 4.0 kg/m2. Kellgren Lawrence (KL) grades were III or IV. The joint line convergence angle was more than 6 degrees, and apparently lateral thrust was observed during walking in all cases. This study has been approved by our Hospital Ethics Committee. Dynamic analysis was performed using 2D / 3D registration technique, in which a 3D bone model created from Computed-tomography images was matched with fluoroscopic images of the knee using a flat panel on a PC for analysis (figure 1). The patent was supported to perform a stepping motion several times during taking fluoroscopic images. One of the phases was extracted and analyzed from the flexed position to the maximum extended position of the knee when a load was applied. The analysis items were the femoral medial translation (mm), femoral varus angle (degree), and femoral rotation angle (degree) relative to the tibia. For statistical analysis, the one-way analysis of variance was performed with the bending angle as the dependent variable and each value as the independent variable. Bonferroni test was used for the multiple comparison test. P value less than 0.01 is considered significant. Results: As a stepping motion, we could analyze from 30 degrees of knee flexion to 0 degrees of extension. The femur was rotated 4.6 degrees with respect to the tibia with extension (figure 2). As it progressed, the femur varused 0.6 degrees against the tibia (figure 3). With extension, the femur moved 3.1 mm medial translation relative to the tibia (figure 4). A statistically significant difference was observed between 30 degrees and 0 degrees of the knee flexion angle in the femoral medial translation and femoral internal rotation. Conclusions: In the varus deformity knees with a large Joint line convergence angle, the femur moved medially with internal rotation relative to the tibia during stepping motion. This phenomenon is the dynamics of lateral thrust, which is thought to accelerate osteoarthritis progression and cause symptom deterioration.View Large Image Figure ViewerDownload Hi-res image Download (PPT)View Large Image Figure ViewerDownload Hi-res image Download (PPT)View Large Image Figure ViewerDownload Hi-res image Download (PPT)

Submuscular Plate Stabilisation After Lengthening: Standard and Modified Techniques.

Introduction:Submuscular plating after lengthening shortened the period of external fixation in distraction osteogenesis of the femur. In the femur, where monolateral or ring fixators had been used for the distraction, plates, could be inserted laterally, anteriorly or medially. Specific technical modification of the plate insertion, however, would be necessary to accommodate the femoral varus angular correction created at the end of the distraction, in the pelvic support osteotomy lengthening.Material and Methods:We reviewed a series of eight cases with standard and modified techniques of plating after lengthening. The amount of lengthening, the period of distraction, the external fixator index and the associated complications were assessed.Results:The mean lengthening was 5cm, with a range of 3cm to 9cm. The external fixation index, the period of external fixators in days in relation to the length of distraction in cm, was between 18 days/cm to 58 days/cm. One patient with quadriceps contracture, underwent quadriceplasty to improve knee flexion. Three patients with transient knee stiffness had resolution with aggressive physiotherapy. One patient with transient hypoesthesia recovered spontaneously. None of the patients developed joint subluxation, deep infection, re-fracture or implant failures.Conclusion:Standard and modified techniques of plating after lengthening were safe and required only a short period of external fixation. The modified technique offered an easier way of plate insertion in a deformed bone.