Treatment of patella fractures by compressive external fixation (CEF)

Transverse fracture of patella is the most common pattern, which contributes 70 % of the total [6]. When the fragments are displaced, then surgery is absolutely indicated to maintain the function of the extensor mechanism. However the nature of patella and high tensile forces challenge the standard surgical techniques used for fracture. The traditional method for patella fracture is tension band wiring (TBW) which provides sound union in most cases [4, 5, 6, 7, 9].

Complications like infection up to 12 %, fixation failure of 22 % and symptomatic hardware in 20 % to 6

% have been reported. We are reporting here, the Afgan compressive external fixator which was introduced by my friend Mr. M. Ismail Wardak.

The technique is based on tensioned biocompatible thin wire external fixation as developed by Academician Prof. Ilizarov for long bones, allows limitless motion [1, 2].

Our aim and purpose of this technique is to review the functional outcomes of patients treated with this novel method. Loss of reduction, and loss of motion, infection and need for second surgery were defined as negative outcomes.

MATERIALS AND METHODS

From January 2010 to January 2015, 25 patients were treated with displaced fractures of the patella. Displaced fractures means gap of more than 3 mm and articular steps more than 2 mm. All the 25 patients were treated by CEF. 12 patients were typical two part transverse fractures of the patella. The following atypical patterns were also treated:

Upper pole fracture – 2;

Lower pole fracture – 4;

Stellate fracture – 2;

Three part fracture – 4.

Pole fracture too small to permit passage of a wire less than 1 cm in size, are not indicated for this novel procedure.

Causes of injures were motor vehicle collision and others. The age ranges were 17 to 65 years (average 35.5 years). Out of 25 patients 20 were men and 5 were women. Time to operation ranged from 8 hours to 10 days. CEF technique is a minimally invasive, percutaneous procedure on 12 closed transverse fractures of patella presenting less than 3 days from the time of injury. The remaining 13 cases were performed through an open procedure. Open reduction was done in all open fractures, upper and lower pole fractures or when accurate reduction was not achieved percutaneously. All the surgeries were performed under spinal anesthesia. Patient follow up was continued at an average of 4 years postoperatively (range 1-4 years).

Ш Bari M.M., Islam Shahidul, Shetu N.H., Mahfuzer R.M. Treatment of patella fractures by compressive external fixation (CEF) // Гений ортопедии. 2016. № 1. С. 30-32.

Журнал клинической и экспериментальной ортопедии им. Г.А. Илизарова № 2, 2016 г.

Surgical procedure

Knee is kept in extension, the fracture fragments are reduced with the help of patellar clamp and it was confirmed by c-arm. Mild traction is applied to the skin medially and laterally to prevent the wires from kinking the skin. Two 1.5 mm wires are passed horizontally through the proximal fragment. Two additional 1.5 mm wires are placed in the distal fragment. It is to be noted that the wire pairs be as far from fracture line as possible. This allows for bowing of the wires and compression of the fracture during tensions of the device.

The wires are passed through the related holes in the clamp assembly. The clamp assemblies are connected to one another (Fig. 1).

The wires are secured by the nuts on the clamp assembly. Tensioning of the wires and compression of the fractures are done by distracting the clamps from one another by turning the distraction nut until the tension wires are tight. The joint is ranged through flexion and extension while checking the stability of fixation by c-arm.

Open reduction technique

An incision is made vertically over the patella, blood clots are cleaned. The fragments are reduced by clamp. We must palpate the articular surface from side to side to confirm the accurate reduction. The retinaculum is repaired. The wound is closed aseptically. No drains are used.

After 1st operative day it is necessary to clean the wire sites with rectified spirit or any kind of antiseptic solution. All the patients were advised to do physical therapy to increase the range of motion. Full range of motion is allowed along with full weight bearing as tolerated by the patient. Sound union was achieved and that was confirmed by X-ray. After 6 to 8 weeks the device was removed.

Fig. 1. Compressive External Fixator

RESULTS

Sound union was achieved in all the fragments at an average of 6 to 8 weeks. That was proved clinically and radiologically. Knee flexion was 90° within 2 to 3 weeks and it was up to 120° by 4 weeks. The Insall knee score for patient function obtained on 12 patients was 96 points and 2 cases who did not carry our instructions, ultimately resulted in less than 90° arc of motion. Complications included 3 wire site inflammation which managed by local care.

We found articular surface incongruity (≥2m) because of incomplete primary reduction in 2 cases (Table 1).

These three patients with articular incongruity developed patellofemoral osteoarthrosis after 3 years follow up postoperatively.

Table 1

Characteristics of fracture patella

Patients	Type of fractures	Insall knee score
12	Transverse	96
2	Upper pole	90
4	Comminuted	92
4	Lower pole	95
3	Stellate	92
Total = 25

Fig. 2.: 1 – Radiograph of transverse fracture of right patella with displacement. 2 – CEF in the right patella (2nd post op). 3 – CEF in the right patella follow up after 3 weeks. 4 – Radiograph of left patella with CEF in situ (after 3 weeks). 5 – Radiographic final result of the patella after removal of CEF. 6 – Clinical appearance of the patient after treatment

DISCUSSION

Our Novel CEF method and device offers advantages compared with traditional method of treatment. All patients healed well without any major complications, despite allowing unrestricted motion.

Our cases compare favorably with the recent large series reported by Smith et al. [4], who analyzed the results of 51 patella fractures treated by TBW. The CEF technique is an external fixation which allows for adherence to the tenets of articular fracture treatment, accurate reduction with stable fixation for immediate motion, leading to the results we have reported. Early functional activity is an added benefit in our patients which is less cost effective. We did not use any brace. The potential effectiveness of CEF has advantages over the existing other technique.

The most significant advantage of CEF is the lack of retained hardware eliminating symptomatic prominence.

Infection is not a problem. So in our series we think that we should be considered for all displaced transverse, pole and selected comminuted patella fractures. Open and previously infected fractures are the best candidate for this technique. Yahmis et al. [8] described the use of ring external fixation to stabilize the comminuted patella fractures. Big advantage is percutaneously application and in the long term no retained hardware. The technique is a simple, it gives absolute stability, provides a significant decrease in hospital stay, gives rapid bone healing and rehabilitation and we think that this method should be considered in the treatment of displaced patella fractures, either open or closed.

Acknowledgement

We are grateful to Dr. Mohammad Ismail Wardak for teaching us this novel technique for treating the patella fractures by CEF.

Disclosures

The authors report no conflict of interest, financial or otherwise concerning the material or methods used in this study or the findings specified in this paper.