HETEROTOPIC OSSIFICATION OF THE ELBOW JOINT

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REVERSE OBLIQUITY INTERTROCHANTERIC FRACTURES

INTRODUCTION

The reverse obliquity intertrochanteric fracture is a distinct type of fracture pattern that is mechanically different from most intertrochanteric fractures. This fracture pattern has been classified under the Orthopaedic Trauma Association classification system as AO/OTA 31-A3 in which the fracture line extends through the lateral femoral cortex distal to the vastus ridge of the greater trochanter. The fracture configuration is opposite to standard intertrochanteric fractures, extending from distal-lateral to proximal medial. Various methods of fixation have been used for this fracture pattern from fixed angled plates and screw-plates to the sliding hip screws and intramedullary fixation devices. Some are biomechanically inappropriate while others are unsuitable for certain fracture configuration. This case write-up will discuss the various fixation devices and the optimum implant in managing these difficult and controversial fractures.

CASE REPORT

Madam LBC is a 92 year old, elderly, Chinese, female, who presented to the Casualty Department, HUKM after a fall at home onto her right hip. She complained of right hip pain and was unable to stand up after the fall. Her gait had always been unsteady after a right sided cerebral vascular accident that had occurred 8 years before. Premorbidly, she was able to walk without any walking aids albeit very slow and unsteady. She was otherwise independent in her activities of daily living. She has no history of hypertension, diabetes, renal or cardiac problems.

On clinical examination, Madam LBC was alert and well oriented. She was pink and her blood pressure and pulse rate was normal. Her right lower limb was externally rotated and shortened and there was tenderness and swelling over the right greater trochanteric region. She had no foot drop, sensory was intact and her distal pulses were normal. Radiographs of the right hip revealed a reverse obliquity intertrochanteric fracture with comminution and extension to the greater trochanter as well as involvement of the lesser trochanter. She was admitted to the orthopaedic female ward and skin traction with 3 kg was applied. She was also initiated on IM Miacalcic 100 iu daily and IM Tramal 50 mg tds for pain relief.

The following day the patient underwent an elective Dynamic Condylar Screw fixation of the right hip under spinal anaesthesia. The patient was placed on a traction table an reduction of the fracture was performed under image intensifier guidance. IV Zinacef 1.5 gm prophylactic antibiotics were given and the skin was cleaned and draped in the usual manner. A longitudinal incision was made centered over the greater trochanter and the fracture site was exposed. K-wires were used initially to stabilize the fracture fragments. The surgeon initially wanted to attempt fixation with a dynamic hip screw but this was abandoned as the insertion site for the lag screw was centred over the fracture site on the lateral cortex of the proximal femur. A DCS guide pin was then inserted under image intensifier guidance and measurement of the length of the lag screw and reaming was performed. The DCS lag screw was then inserted and a 95 degrees 8 hole DCS plate was placed into position and the fracture was reduced again. The plate with then fixed with 5 cortical screws. The wound was then washed and closure of the wound in the usual manner was done.

The immediate post-operative period was uneventful and check radiographs were acceptable. She was only allowed ambulation on a wheelchair as the fracture was comminuted and unstable. On post-operative day 5, Madam LBC was discharged well. Unfortunately, at her first orthopaedic clinic follow-up visit at 2 weeks post-op, the patient complained of right leg swelling over the past 2 days. The wound was clean and there was no calf tenderness. Madam LBC was readmitted to the ward for further investigation. Doppler ultrasound confirmed the diagnosis of right femoral vein thrombosis. She was immediately started on S/C Clexane 60mg 12 hourly which was given for a total of 5 days and Tab Warfarin with doses adjusted to maintain an optimum INR therapeutic range of 2.1 to 4.8. She was still only allowed mobilization with a wheelchair.

DISCUSSION

The reverse obliquity fracture of the proximal femur is a distinct fracture pattern that is mechanically different from most intertrochanteric fractures. The fracture line in most intertrochanteric fractures runs obliquely from the greater trochanter proximally to the lesser trochanter. The reverse obliquity fracture of the proximal part of the femur has the opposite configuration, with the major fracture line running from distal-lateral to proximal-medial. [1]

Evans in 1949 and subsequently, Jensen and Michaelson classified intertrochanteric fractures based on the likelihood of achieving and maintaining anatomic reduction. This classification stresses the importance of an intact posteromedial cortex for maintaining a stable reduction. Unstable fractures are those with comminution of the posteromedial cortex, subtrochanteric extension, and reverse obliquity patterns. The Evans classification has poor reproducibility, thus most surgeons find it more useful and simpler to classify the fracture patterns into stable and unstable fractures. [5]

The Orthopaedic Trauma Association has classified fractures about the trochanter as AO/OTA 31-A, delineating them as extracapsular fractures of the hip. These fractures are further subdivided into groups A1, A2, and A3 fractures. A1 fractures are simple, 2-part fractures. A2 have multiple fragments. A3 fractures include reverse oblique and transverse fracture patterns. The distinctive characteristic of A3 fractures is the fracture line extends through the lateral femoral cortex distal to the vastus ridge of the greater trochanter. A3 fractures have been classified differently by different authors. A3 fractures have been called in some studies as unstable intertrochanteric fractures. Other studies describe these fractures as a combination of intertrochanteric and subtrochanteric fractures. [4] Some authors have even classified this fracture as a Type II-A subtrochanteric fracture using the Russell-Taylor Classification as this fracture pattern behaves more like a subtrochanteric fracture than an intertorchanteric fracture with regards to fracture forces and instability patterns. [7]

Reverse obliquity intertrochanteric fractures of the femur are uncommon but not rare fractures. This fracture pattern accounts to between 5% to 16.6% of all intertrochanteric and subtrochanteric fractures.[1,6] The reverse obliquity intertrochanteric fractures of the femur are recognized as biomechanically different from standard intertrochanteric fractures. They behave more like subtrochanteric fractures than intertrochanteric fractures with regards to fracture forces and instability patterns. The tendency for medialization of the femoral shaft in relation to the head and neck components of the fracture places significant deforming forces on the internal fixation. [7]

The fracture pattern of standard intertrochanteric fractures can be effectively treated with sliding-screw devices that allow compression and collapse of the fracture into a stable configuration. The key to the success of these devices is controlled postoperative impaction of the fracture to a stable configuration. This concept requires that the direction of compression be perpendicular to the major fracture line. The application of this concept to reverse obliquity fractures is unfavorable because sliding of the proximal fragment and medialization of the distal fragment can lead to fracture distraction. There is no medial buttress and the implant acts as a load-bearing device. [1]

Haidukewych et al. retrospectively studied 2472 patients with hip fractures between 1988 and 1998 of which 1035 were classified as intertrochanteric or subtrochanteric. Fifty-five of these were reverse obliquity intertrochanteric fractures. Forty-nine were followed up until the fracture united or revision operation was performed. Thirty-two (68%) of 47 hips treated with internal fixation healed without an additional operation. Fifteen of 47 failed to heal or had failure of fixation. The failure rate was 9 of 16 (56%) for sliding hip screws, 3 of 10 (30%) for dynamic condylar screws, 2 of 15 (13%0 for blade plates, 1 of 3 (33%) for cephalomedullary nails, and 0 of 3 (0%) for intramedullary hip screws. Use of the fixed angle devices (the blade plate and the dynamic condylar screw) resulted in fewer failures than did use of the sliding hip screw. (p=0.023). The authors concluded that 95 fixed-angle internal fixation devices performed significantly better than did sliding hip screws. Results were worse for fractures with poor reduction and those with a poorly placed implant. [1]

In a letter to the editor, Stocks concurred with Haidukewych et al. that there is little in the literature to guide treatment of these difficult fractures and that a sliding hip screw has a relatively high failure rate. He observed that despite this, the sliding hip screw is often used for reverse obliquity fractures. This may be because firstly, emergency department radiographs may fail to demonstrate the reverse obliquity pattern. Thus, no plan was made preoperatively to use an implant other than a sliding hip screw. Second, the surgeon may be unfamiliar with the reverse obliquity pattern and how it differs biomechanically from a standard intertrochanteric hip fracture. He also suggested that all intertrochanteric fractures should be referred by their OTA classification before choosing the method of fixation to minimize suboptimal treatment choices. Stocks also concurred that 95 fixed-angle devices perform better than sliding hip screws as the former allows more fixation in the proximal fragment and provides a better buttress on the lateral cortex of the proximal fragment to prevent varus collapse. A relatively good success with intramedullary fixation has been observed as well. [6]

In contrast, Zickel, also in a letter to the editor, commented that Haidukewych et al. lacked perspective on the treatment of reverse obliquity intertrochanteric fractures. He suggested that Haidukewych refer to an article An Intramedullary Fixation Device for the Proximal Part of the Femur . Nine YearsExperience. (1976;58:866-72) in which a follow-up analysis of 84 nonpathological fractures treated with the Zickel nail device. This article had reported 64 oblique pattern fractures treated with the Zickel nail device that had healed uneventfully without the necessity for either reoperation or bone grafting. He commented that it is poorly understood that when a screw-plate or nail-plate device is used to fix this subtrochanteric fracture, the stresses are on the plate and the compression screw is merely anchoring that plate to the proximal part of the femur. Zickel also expressed his surprise thatu Haidukewych et al. failed to realize that intramedullary fixation of this fracture is not only the safest method of fixation but also one that has been used for a long time. [9]

Watson et al. compared the Medoff sliding plate with a standard compression hip screw in a randomized, prospective study for the fixation of 160 stable and unstable intertrochanteric fractures. Stable fracture pattern (46 hips) united without complication in both treatment groups. Unstable fractures (114 hips) which included 8 reverse obliquity fractures (4 treated with sliding hip screw and 4 with Medoff plate) had a overall failure rate of 9.6%. The failure rate with the use of a compression hip screw was 14% (9 patients), significantly greater than 3% (2 patients) with the Medoff plate. However the operating time and estimated blood losses were greater with the use of the Medoff plate. [8]

Kummer et al. in a biomechanical study using sawbone composite femurs showed that significantly more shaft medialization occurred with reverse obliquity fracture patterns when the Medoff plate was fully dynamized. Approximately 80% of this translation occurred within the first 100 loading cycles. When the lag screw was locked and only the femoral plate permitted to slide, minimal translation (