SIMPLIFIED CALCULATION FOR CORRECTIVE OSTEOTOMIES OF LONG BONES

Osteotomy wedge angle - Aiming to achieve perfection with new device: Pre-clinical stage

Introduction

The surgical execution of osteotomy requires precision in measuring the wedge angle. The pre-operative planning methods are plenty and so are few devices for high tibial osteotomy. But struggle happens for those bony areas other than proximal tibia where alignment correction is needed. The new device is proposed to address this surgical problem. The ease of measuring angle for bony wedge angle, in any bone, independent of its width and in any plane, is the question being solved with the proposed devices.

Methods

Two jig instruments have been shown in the study. First one the curved with direct angle measuring marking in degrees on the body. K wire is accepted through the tower exactly showing the desired angle. The second jig instrument is flat design with marking in millimeters. This device works on trigonometric principle of sum of angles of any triangle is equal to 180°. The jig can be removed leaving the k wires in place to complete the final osteotomy once confirmed.

Results

It's a pre-clinical stage study. The saw bone models show encouraging measurements and perfect execution of angle at the osteotomy site.

Discussion

HTO has been researched a lot with many options of surgical devices. The criticism of using known devices is the variable accuracy, especially for the smaller width of tibial metaphysis. One major limitation of these available instruments is they can be used only for proximal tibial metaphysis. For any other surgical sites like distal femur, distal tibia, distal humerus or tibial slope correction neither these HTO jigs will work nor there is any available universal instrument as such. The common misconception of one degree equal to 1 mm does not stand true at all bony sites. Hence there was a need to solve this problem with universal jig. I have designed two new devices which are currently at pre-clinical stage. The curve device has limitations which get corrected in straight device. The philosophy changes from one direct measurement with two tips of wires forming the angle in a curved device to indirect measurement by simple trigonometric calculation in a straight device. The proposed new device would work in any bone, for any trapezoidal wedge shape osteotomy using simple user-friendly k wires.

Two-level Osteotomy for Genu Valgum with Tibia Valga: Surgical Planning and Execution

Introduction:

Proximal tibial injury leading to tibia valga which, in turn, leading to genu valgum is well described deformity. Management options vary between growth modulation and corrective osteotomy. Osteotomy which is used for skeletally mature patients can either be done in single stage or in multiple stages or in gradual manner.

Case Report:

We describe here a method to obtain single-stage correction with two-level osteotomy in a 20-year-old patient. It includes medial closing wedge osteotomy at distal femur and translational osteotomy at tibial shaft.

Conclusion:

This method of two-level osteotomy recognizes and treats two deformities (i.e., genu valgum and tibia valga) separately and achieves correction in one stage with perfect restoration of mechanical axis of lower limb and joint line obliquity of knee.

Results of the modified reverse step-cut osteotomy in paediatric cubitus varus

PURPOSE

Cubitus varus deformity occurs in children as a late consequence of supracondylar fracture of the distal humerus. Different types of corrective osteotomies have been described, but a gold standard has not yet been established. The aim of this study is to report the clinical, radiological, and cosmetic outcome of the modified reverse step-cut osteotomy technique.

METHODS

This study was conducted on 15 cases, which were operated during the period between July 2015 and June 2016. We used the technique modified reverse step-cut osteotomy with the calculated medial translation of the distal fragment to correct varus and sagittal plane deformity and to achieve anatomical alignment of the forearm axis with the axis of the humerus. Follow-up was done for two years. Pre-operative and post-operative clinical and radiological parameters were compared, and patient satisfaction was assessed.

RESULTS

The mean pre-operative humerus-elbow-wrist (HEW) angle was - 22.4°; it improved to + 9.4° post-operatively. The pre-operative mean range of motion was 131.6°, and the post-operative mean was 132°. The clinico-radiological outcome was assessed according to Oppenheim criteria. There was an excellent result in nine patients (60%), a good result in five patients (33.3%), and poor results in one patient (6.6%). Cosmetic outcome was assessed as per Barrett's criteria, excellent result in thirteen patients (86.6%) and poor results in two patients (13.3%). Post-operative lateral condylar prominence index (LCPI) was compared with the normal side, and there was no significant difference.

CONCLUSION

We have achieved satisfactory results with acceptable cosmetic appearance and functional outcomes with minimal complications. We recommend this technique as a safe, reliable, reproducible, technically easy procedure for correction of cubitus varus deformity.

The Rule of 57: Orthopaedic Trigonometry Made Easy

INTRODUCTION

The Rule of 57 is an easy method for planning osteotomies and calculating translations when correcting spine and limb deformities.

METHODS

The rule is based on the mathematical principle that a circle with a radius of 57 mm has a circumference of 360 mm where each 1° of the circle subtends an arc of 1 mm in length.

RESULTS

Thus a 1 mm opening or closing wedge osteotomy with a width of 57 mm would result in 1° of angular correction.

DISCUSSION

This basic geometric shape can be extrapolated in many ways to determine proper alignment for preoperative planning, performing osteotomies, understanding guided growth, and executing a variety of deformity corrections.