The effect on mechanical axis deviation of femoral lengthening with an intramedullary telescopic nail

Femoral lengthening with intramedullary nails can create alterations in the mechanical axis of the limb. This is based on the relationship of the anatomic femur axis to the mechanical femur axis, which is typically 5–9 degrees valgus. We developed trigonometric formulas to calculate the predicted change, using the lengths of the tibia, femur, and whole limb; the amount of lengthening; and the angle between the anatomic and the mechanical axis of the femur. We recognized three patterns depending on whether the overall limb mechanical axis is lateral (valgus), medial (varus), or straight through the center of the knee. The varus and valgus patterns lead to similar formulas. When the mechanical axis goes directly through the center of the knee joint, the formula simplifies. These formulas could be incorporated into digital radiographic programs to predict the change in mechanical axis deviation that will develop from lengthening along the anatomic femur axis with an intramedullary lengthening nail.

Download Full-text

Effect of foot deformity on conventional mechanical axis deviation and ground mechanical axis deviation during single leg stance and two leg stance in genu varum

The Knee ◽

10.1016/j.knee.2007.07.009 ◽

2007 ◽

Vol 14 (6) ◽

pp. 452-457 ◽

Cited By ~ 24

Author(s):

Sameer Shrikrishna Desai ◽

Gautam M. Shetty ◽

Hae-Ryong Song ◽

Seok Hyun Lee ◽

Tae Young Kim ◽

...

Keyword(s):

Mechanical Axis ◽

Genu Varum ◽

Axis Deviation ◽

Foot Deformity ◽

Mechanical Axis Deviation ◽

Single Leg Stance

Download Full-text

Interobserver and Intraobserver Reliability in the Evaluation of Mechanical Axis Deviation

Journal of Pediatric Orthopaedics ◽

10.1097/bpo.0b013e31819b9188 ◽

2009 ◽

Vol 29 (3) ◽

pp. 281-284 ◽

Cited By ~ 20

Author(s):

J. Eric Gordon ◽

Ryan C. Chen ◽

Matthew B. Dobbs ◽

Scott J. Luhmann ◽

Margaret M. Rich ◽

...

Keyword(s):

Mechanical Axis ◽

Intraobserver Reliability ◽

Axis Deviation ◽

Mechanical Axis Deviation

Download Full-text

An Innovative Method of Assessing the Mechanical Axis Deviation in the Lower Limb in Standing Position

JOURNAL FOR CLINICAL AND DIAGNOSTIC RESEARCH ◽

10.7860/jcdr/2016/17324.8042 ◽

2016 ◽

Author(s):

Jagannath Kamath

Keyword(s):

Lower Limb ◽

Mechanical Axis ◽

Standing Position ◽

Axis Deviation ◽

Mechanical Axis Deviation ◽

Innovative Method

Download Full-text

Genu valgum deformity – correction by a wedgeless implantless femoral “V” osteotomy

Acta Orthopaedica Belgica ◽

10.52628/87.2.07 ◽

2021 ◽

Vol 87 (2) ◽

pp. 247-254

Author(s):

Amrit Goyal ◽

Vikas Gupta ◽

Meenakshi Goyal ◽

Rajesh Chandra ◽

Vinod K Sharma

Keyword(s):

Internal Fixation ◽

Mechanical Axis ◽

Deformity Correction ◽

Image Intensifier ◽

Valgus Knee ◽

Axis Deviation ◽

Mechanical Axis Deviation ◽

Tibiofemoral Angle ◽

Average Value ◽

Intermalleolar Distance

Coronal malalignment of the knee joint is very common in developing countries especially because of nutritional rickets. Significant valgus deformity needs to be treated surgically to improve appearance, gait and function of the patient. The purpose of this prospective study was to evaluate the results of supracondylar “V” osteotomy as a surgical technique for correction of the valgus knee deformity. This study was conducted in a tertiary level teaching hospital and 30 cases were included in the study. For all the patients deformity was assessed using ana- tomical tibiofemoral angle, mechanical axis deviation and intermalleolar distance preoperatively and post- operatively. The average age of our patients was 13.7 years and the average follow up was3.29 years (1.39-14.22 yrs). Clinically the average value of intermalleolar distance preoperatively was 16cm and 3.2 cm postperatively. Average pre-operative tibiofemoral angle was 23° and the average postoperative angle was 6 0 which was found to be statistically significant using the Paired t test (p<0.005). The average value of preoperative mechanical axis deviation was 3.1 cm which decreased to an average value of 1.1 cm postoperatively. The results with this technique have been encouraging. The advantages of this technique are low morbidity, good stability allowing early ambulation, ability to adjust alignment postoperatively by casting and no need for internal fixation. Few studies have been conducted on osteotomies that do not require internal fixation and are inherently stable. This technique has the advantage of practically no occurrence of any infection or a second surgery to remove hardware in children and adolescents. Since no specialized instrumentation, image intensifier and implants are required, it is cost effective and can be used in any primary care or district level surgical setup in a developing country like ours.

Download Full-text

A computer assessment of the effect of hindfoot alignment on mechanical axis deviation

Computer Methods and Programs in Biomedicine ◽

10.1016/j.cmpb.2013.09.010 ◽

2014 ◽

Vol 113 (1) ◽

pp. 126-132 ◽

Cited By ~ 6

Author(s):

Naven Duggal ◽

Gabrielle M. Paci ◽

Abhinav Narain ◽

Leandro Grimaldi Bournissaint ◽

Ara Nazarian

Keyword(s):

Mechanical Axis ◽

Axis Deviation ◽

Computer Assessment ◽

Hindfoot Alignment ◽

Mechanical Axis Deviation

Download Full-text

A Computer Model Assessment of the Effect of Hindfoot Alignment on Mechanical Axis Deviation and Ankle Fractures

Foot & Ankle Orthopaedics ◽

10.1177/2473011418s00214 ◽

2018 ◽

Vol 3 (3) ◽

pp. 2473011418S0021

Author(s):

Naven Duggal ◽

Patrick Williamson ◽

Ara Nazarian

Keyword(s):

Compressive Stress ◽

Lower Limb ◽

Muscle Force ◽

Mechanical Axis ◽

Stress Fractures ◽

Biomechanical Study ◽

Lateral Malleolus ◽

Axis Deviation ◽

Pes Planus ◽

Mechanical Axis Deviation

Category: Basic Sciences/Biologics Introduction/Purpose: Conventional mechanical axis is calculated from the center of the femoral head to the center of the ankle. Mechanical axis deviation of the lower limb can be associated with a pes planus hindfoot. Malalignment of the lower limb has been shown to increase progression of osteoarthritis of the knee and ankle and decrease joint arthroplasty longevity. Clinically, a pes planus hindfoot has also been seen with patients who present with a stress fracture of the lateral malleolus. This biomechanical study aims to utilize computer modeling to evaluate the hypothesis that altered force transmission on the lateral malleolus with resultant stress fractures in a pes planus model is attributable to mechanical axis deviation. Methods: A free-body diagram of the fibula in single leg stance was generated by modeling the fibula as a uniform cylinder. It includes the axially applied load and a single evertor muscle force as an eccentric load applied to the mid-diaphysis . Previously derived relationships between body weight (BW = 667 N, 150lbs) and a) normal axial fibula load (BW*0.17) and b) muscle force (BW*0.25) were used. Fibula length (286.5 mm) and diameter (8 mm) were derived from anthropological data. Mechanical axis deviation in pes planus was simulated in two manners: 1) increased (2 and 3 times normal) axial fibula load and 2) increased evertor muscle force. The compressive stress along the length of the bone was determined through static analysis and the total applied load was compared to theoretical Euler buckling load. Results: Increasing the load on the fibula, either by increasing the axial load (Figure 1A) or the muscle load (Figure 1B), increases the maximum compressive stress below the lateral muscle origins, namely the section between the distal tibiofibular ligaments and the evertor muscles. The compressive stress for both cases was less than the compressive yield stress of cortical bone (200 MPa) and cancellous bone (100 MPa) even as the force was increased to the critical buckling value. This model serves as a first attempt to relate the spatial distribution of stress in the fibula with muscle force, axial load, and compressive stress in light of distal fibular fractures associated with pes planus. Conclusion: The importance of lower extremity mechanical axis deviation is well established in the progression of arthritis in the knee and ankle. The role of the mechanical axis in the predisposition of stress fractures around the ankle has not been evaluated in the literature. This biomechanical study represents the first attempt to understand how deviation of the mechanical axis can result in stress fractures of the lateral malleolus. Future studies including a finite element analysis will provide further information and the results of these studies may alter how clinicians treat patients with stress fractures of the fibula.

Download Full-text

Simultaneous Bilateral Femoral and Tibial Lengthening in Achondroplasia

Children ◽

10.3390/children8090749 ◽

2021 ◽

Vol 8 (9) ◽

pp. 749

Author(s):

Lior Shabtai ◽

Julio J. Jauregui ◽

John E. Herzenberg ◽

Martin G. Gesheff ◽

Shawn C. Standard ◽

...

Keyword(s):

Adverse Events ◽

Medical Records ◽

Soft Tissues ◽

Mechanical Axis ◽

Duration Of Treatment ◽

Mechanical Axis Deviation ◽

Tibial Lengthening ◽

Femoral Lengthening ◽

End Of Treatment

Previous studies on lengthening for achondroplasia have reported bilateral extensive femoral lengthening followed by bilateral extensive tibial lengthening. To decrease trauma on soft tissues and joints, we propose bilateral simultaneous moderate femoral lengthening and moderate tibial lengthening followed by a similar repeat lengthening a few years later. Fifty patients with achondroplasia underwent 65 simultaneous bilateral femoral and tibial lengthening procedures. Segment lengthening amount and adverse events were obtained from medical records. Mean follow-up after bone healing was 35.6 months. Mean tibial lengthening was 52 mm; mean femoral lengthening was 72 mm. Average healing index was 1.4 months/cm for the tibia and 1 month/cm for the femur. Mean duration of treatment with external fixation was 6.7 months (range, 4.4–10.5 months). Thirty-eight (76%) of 50 patients experienced one or more adverse events during lengthening. We observed 78 adverse events, 35 (45%) of which required additional surgical procedures. All resolved by the end of treatment. Mechanical axis deviation improved from a mean of 15 mm medially to 8 mm medially. Simultaneous lengthening of four segments in patients with achondroplasia is a feasible strategy. Compared with isolated femoral or tibial lengthening, distributing the lengthening between the femur and tibia decreases total external fixator time.

Download Full-text

Osteochondritis Dissecans Lesion Location Is Highly Concordant With Mechanical Axis Deviation

The American Journal of Sports Medicine ◽

10.1177/0363546520905567 ◽

2020 ◽

Vol 48 (4) ◽

pp. 871-875

Author(s):

Matthew L. Brown ◽

Julie C. McCauley ◽

Guilherme C. Gracitelli ◽

William D. Bugbee

Keyword(s):

Lower Extremity ◽

Osteochondritis Dissecans ◽

Distal Femur ◽

Mechanical Axis ◽

Femoral Condyle ◽

Lesion Size ◽

Osteochondral Allograft ◽

Axis Deviation ◽

Mechanical Axis Deviation ◽

Lesion Location

Background: The cause of osteochondritis dissecans (OCD) is unknown. Purpose: To determine if mechanical axis deviation correlates with OCD lesion location in the knee, if degree of mechanical axis deviation correlates with size of OCD lesion, and if the deformity was primarily in the distal femur or proximal tibia. Study Design: Cross-sectional study; Level of evidence, 3. Methods: We identified 61 knees that underwent osteochondral allograft (OCA) transplantation for femoral condyle OCD lesions and used preoperative lower extremity alignment radiographs to measure lower extremity mechanical axis, mechanical lateral distal femoral angle (mLDFA), mechanical medial proximal tibial angle (mMPTA), and hip-knee-ankle angle. Lesion location and area were retrieved from operative records. Results: The location of the OCD lesion was the medial femoral condyle (MFC) for 37 knees and lateral femoral condyle (LFC) for 24 knees. Among knees with MFC lesions, alignment was varus in 25 (68%). Conversely, knees with LFC lesions had valgus alignment in 16 (67%). The mLFDA was significantly more valgus in the LFC group. mMPTA was not different between MFC and LFC groups. There was no significant correlation between degree of mechanical axis deviation and lesion size. Conclusion: In this cohort, two-thirds of patients with symptomatic OCD lesions had associated mechanical axis deviation. Lesion location correlated with mechanical axis deviation (LFC lesions were associated with a deformity in the distal femur). Degree of deformity was not correlated with lesion size. Mechanical axis deviation may play a role in OCD pathogenesis. These data do not allow analysis of the role of mechanical axis deviation in causation or prognosis of OCD lesions, but surgeons treating OCD should be aware of this common association.

Download Full-text