Cubitus Varus – Correction by Distraction Osteogenesis

Cubitus varus is most common complication of malunited supracondylar fracture in children. Lack of remodelling establishes the deformity. Cosmetic appearance is the common indication for surgery, which more authors now agree, should be done as early as deformity becomes established. Many osteotomies have been described but most, if not all are technically demanding and are being replaced for want of better stabilization, three dimensional correction and above all simplicity. Medial open wedge osteotomy fell in to disrepute because of its inherent instability, need of bone graft and neurological complications. Various newer techniques have been tried to correct the deformity in three dimensional planes but to achieve that, accurate preoperative planning, calculations and special attention to surgical detail are needed. And still results are no better than simple lateral close wedge osteotomy. We present our clinical study to correct this deformity by doing gradual medial opening wedge osteotomy in lower humerus; stabilizing and distracting it with an external fixator – cum – distractor.

Material and Methods

During 1996 to 1999, a total of 30 patients of cubitus varus deformity of more than six months duration were admitted in the Department of Orthopaedics, Pt. B.D Sharma, Post Graduate Institute of Medical Sciences. Rohtak, Haryana. Medial osteotomy was performed and distraction was done by a simple external fixator – cum – distractor.

Apparatus: The external fixator – cum – distractor is made up of stainless steel and consists of three portions : one central hexagonal hollow portion which threaded from inside (turnbuckle) and two straight end pieces, both threaded and can be telescoped in or out of turnbuckle. The end pieces have holes for schanz screws. One full turn of hexagonal turnbuckle leads to distraction of about 3 mm. One third of full turn per day will thus distract 1 mm.

The Patients: The prospective study included 30 children of age 6 to 14 years with cubitus varus deformity ranging from 17° to 40°. Apart from routine investigations required for fitness of patients for anaesthesia and surgery, a roentgenogram of both elbows with arm and forearm in AP view in full extension and lateral view in flexion were taken. Humero – elbow – wrist (HEW) angle was measured on both sides and arc of motion was noted. Clinically carrying angles of both sides were assessed and compared. Preoperatively patients as well as their parents were taught to practice active elbow movements and the distraction process of the apparatus.

Operative Procedure: All surgeries were performed under general anaesthesia under full aseptic conditions and pneumatic tourniquet. Procedure was done under image intensifier or X-­ray control. Postero – medial longitudinal incision was given along lower third of shaft of humerus for about 3 to 4 inches in length starting from just below elbow joint upwards. After superficial dissection, ulnar nerve was exposed, isolated and retracted anteriorly. Shaft humerus was then approached by going through the fibers of triceps. Two schanz screws were passed distal to the proposed site of osteotomy which is just above and tangential to olecrenon fossa under radiological control to make it parallel to joint line. The fixator – cum – distractor was applied to the screws and then through the holes of proximal end piece of the apparatus; two proximal schanz screws were passed slightly posterior in coronal plane to the distal ones. Now the apparatus was detached from the screws and osteotomy was performed with a sharp osteotome taking care to leave a lateral osteoperiosteal hinge. This hinge is important to stabilize the distal fragment. Tight medial intermuscular septum was incised and triceps fibers found to be shifted medially were erased from medial side of olecranon. Mar nerve was transposed anteriorly, avoiding its kinking in the musculofascial sleeve proximally. The apparatus was reapplied away from skin, periosteum stiched over the site of osteotomy and closure of wound was done in layers. No splint was required in most cases.

Postoperative: Active elbow movements were started from the first postoperative day. Stitches were removed after ten days of surgery. Pin site dressings with betadine lotion were done on alternate days and were taught to the patients as well as parents.

Distraction Process: Gradual distraction was started from third to fifth post-operative day onwards (as most patients were children with higher osteogenic potential) at the rate of one mm/day in 8 to 10 steps till the deformity was fully corrected. After correction of deformity (achieving HEW angle and carrying angle identical to normal side) the apparatus was kept in place till full consolidation at the site of osteotomy. Distraction process and pin site dressings were taught to the patients and/or their parents and they did it at their homes. Fixator – cum – distractor was removed after full consolidation (about 7 to 9 weeks) at osteotomy site.

Follow Up: All patients were followed up for minimum of two years duration at regular fortnight intervals till removal of apparatus and then three monthly. The correction of deformity and formation of callus was assessed clinically by carrying angle and radiologically by HEW angle. After achieving the desired amount of correction, patients were regularly followed-up with apparatus in place till there was full consolidation at the site of osteotomy. Full consolidation tool about 8 to 9 weeks in most patients. Fixator – cum – distractor was removed in outdoor, taking care to avoid intanglement of ulnar nerve, by pushing the nerve anteriorly (away) from the threads of schanz screws).

Results

Medial opening wedge osteotomy stabilized with external fixator – cum – distractor was used to correct cubitus varus deformity in 30 patients (25 males and 5 females) with age group from 6 to 14 years. Ulnar nerve was transposed anteriorly in all patients and image intensifier or X-ray control was used in all cases. Distraction was started from 3 rd to 5 th day of surgery at rate of one mm/per day in 8 to 10 divided intervals and continued till desired amount of correction was achieved (checked clinically by carrying angle and radiologically by HEW angle). At about 7-9 weeks the callus at the site of osteotomy consolidated and the apparatus was removed. The removal was done in routine outdoor and under mild sedation. Mean cubitus varus deformity corrected by this technique was 29.6° (-10° to 42°).

In 28 cases, the correction achieved was within 5° of normal. In one case it was within 6° of normal. This patient already had lateral closed wedge osteotomy done elsewhere and had a recurrence of cubitus varus deformity. Only one case had a poor result because the parents did not distract the callus for 3 weeks and in that time the osteotomy consolidated and no correction was possible. There was no case of neurological deficit, not even during removal of schanz screws. Mild stiffness which was present in 2 cases disappeared after removal of the appratus. Superficial pin site infection was the main complication in 3 patients (10%). It subsided with oral antibiotic and proper pin site dressing. The average follow-up of patients was about 34 months.

Discussion

Various methods have been described in literature to correct cubitus varus deformity by corrective osteotomy followed by fixation with POP cast, wires, plates and screws. Most osteotomies are based on lateral close wedge osteotomy of French. Others have tried to correct varus and medial rotation by step-cut technique, dome osteotomy, pentalateral osteotomy and numerous other techniques. The main drawback of these procedures which we faced was the accuracy of osteotomy cuts which need to be very precise. These osteotomies though well described, are a difficult proposition for even a trained surgeon as even 5° to 10 0 of over or under correction makes the outcome unacceptable to the patient. Other lacunae cited in the literature have been : recurrence, loss of fixation, lazy S deformity and neurological deficit. Widespread use of llizarov’s ring fixator for correction of bony deformities around the knee joint gave us an idea to utilize the principle of distraction osteogenesis and law of tension stress in our technique. As most of our patients were in younger age group, union was no problem and consolidation took 7 to 9 weeks in all cases. The rate of distraction was kept at 1 mm/day in 8 to 10 divided times and was done by the patient and/or parent themselves at home. Later as we found early appearance of callus, we increased the rate of distraction to 2 mm/day. Rotational element was tried to be corrected by placing the proximal screws posteriorly and distal screws anteriorly in coronal plane, although many authors have noted that rotational deformity is difficult to correct in very thin supracondylar region and it is of no consequence and should be ignored. Theoretically during distraction. rotational element should have also been corrected but we were unable to confirm these findings. We incised the medial intermuscular septum and erased some medial fibres of triceps from olecranon to minimise the recurrence of deformity by pull of the septum and triceps muscles. We had no case of lazy S deformity. This deformity, which occurs with lateral closed wedge osteotomy, is because of the appearance of protruding lateral epicondyle of humerus from where the wedge has been removed. As our osteotomy was medial open wedge type, we did not face this cosmetic problem in any of our case. Our procedure has some added advantages described below.

Advantages of exposure: 1. Ulnar nerve can be seen and transposed anteriorly. 2. Medial soft tissue release can be done at the same sitting. 3. Posteromedial scar gives a better cosmetic appeal as it hides from the casual sight.

Advantages of gradual medial opening osteotomy: 1. Length is gained 2. No bone graft is required; unnecessary morbidity is thus avoided. 3. Gradual distraction of callus gives stability. 4. Reduced chances of lazy S deformity. 5. No need of preoperative or peroperative calculation of cuts and angles.

Advantages of apparatus : 1. Cheap and easily available. 2. Very easy to apply and removal is an outdoor procedure. 3. Patient can himself distract, so reduced hospital stay. 4. Elbow motion and daily activities can go on unhindered, so early and easy physiotherapy and no stiffness associated with plaster immobilization. 5. Desired amount of correction can be achieved to the satisfaction of patient/ parent as they can participate and judge for themselves.

The procedure has few disadvantages as well: 1. Pin site infection which can be minimised by appropriate pin site dressing and care. 2. X-ray control or image intensifier is needed for proper placement of juxtaarticular schanz screws. 3. Initially patient may have difficulty in adapting to the medially place apparatus in the arm which touches the thoracic cage area and patient has to keep shoulder abducted while sleeping. 4. Being uniplanner apparatus it is not as stable as Ilizarov’s ring fixator.

The simple versatile technical of application and easy removal of apparatus and most importantly its accuracy and post operative simplicity to achieve an excellent cosmetic outcome which is most important to the patient, prompts us to recommend the procedure.

Summary

Cubitus varus deformity in thirty children was corrected by gradual medial opening wedge osteotomy. The osteotomy was stabilized and distracted by simple external fixator – cum – distractor. The patients of both sexes and age from 6 to 14 years, had varus deformity from 17° to 43°. We achieved good to excellent results in 28 cases as regards to correction of deformity and range of motion at elbow joint. None of the cases had neurological deficit or permanent stiffness. One case had fair result due to under – correction and another case had a poor result as osteotomy united before correction. The main complication faced was superficial pin-site infection particularly in summer season and a in fatty children but was managed by good pinsite dressing and care. The technique has been found to be quite effective, technically simple, cosmetically acceptable and with little, if any, lazy S deformity.

Leave a Reply

Your email address will not be published. Required fields are marked *

Back to Top