Article, Orthopedics

Avoiding disaster in the management of dislocated hip hemiarthroplasties: case presentation, diagnosis, and management

Case Report

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American Journal of Emergency Medicine

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Avoiding disaster in the management of dislocated hip hemiarthroplasties: case presentation, diagnosis, and management?

Abstract

Dislocation of a hip hemiarthroplasty is a Rare occurrence; however, a devastating complication during the closed reduction attempt in the emergency department may occur without full understanding and proper reduction techniques: femoral component displacement and fracture.

This is a report of displacement of the femoral component and frac- ture after attempted closed reduction of a dislocated, press-fit bipolar hemiarthroplasty. This complication required operative revision of the femoral component to a cemented stem, resulting in stable reduction with no further dislocation episodes for our 78-year-old female patient. This case provides a rare but potentially devastating complication after hemiarthroplasty dislocation. It should serve as a reminder to approach these reductions with caution. Injury recognition, complete radiographic analysis, and proper reduction techniques will limit un-

necessary damage and expedite the appropriate treatment.

Hemiarthroplasty (HA) of the hip is a common procedure used to treat displaced fractures of the femoral neck in patients who would not benefit from a total hip arthroplasty (THA). Dislocation is less com- mon after HA compared with THA [1]; however, at a reported rate of be- tween 3% and 9%, it is not insignificant [2-4]. Typically, an attempt at closed reduction is made with the aid of sedation as the first line of treatment in the emergency department.

Displacement of the femoral stem during closed reduction is a rare complication and has been reported after THA [5-9]. This has not yet been reported with the use of press-fit HA to the author’s knowledge.

We describe the case of a 78-year-old woman who sustained dis-

placement of the femoral component after attempted closed reduction of a dislocated, press-fit bipolar HA in the emergency department. The mechanism of injury, radiographic recognition, diagnosis and manage- ment in the emergency department, operative intervention, and follow-up are discussed.

A 78-year-old woman with a history of multiple falls as well as hy- pertension, type 2 diabetes, hypothyroidism, polymyalgia rheumatica, dementia, and right Middle cerebral artery stroke with residual left- sided weakness presented to the emergency department with a displaced Femoral neck fracture after a nonsyncopal fall (Fig. 1). In the operating room, a posterior approach to the hip was used to place a size 10 press-fit femoral component with a 46-mm bipolar head.

? This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

The patient’s postoperative course was uneventful, and the patient was discharged to a rehabilitation facility on postoperative day 3. Hip radiographs were obtained before her discharge confirming stable im- plants (Fig. 2).

The patient returned to the emergency department on postoperative day 9 after experiencing a fall at a subacute nursing facility. A left hip ra- diograph revealed a dislocation of the HA with superior migration (Fig. 3). Under conscious sedation, closed reduction was attempted in the emergency department. Standard reduction maneuvers for a poste- rior dislocation were used where the hip and knee were flexed to 90? and traction was applied with internal rotation (Fig. 4). No tactile reduc- tion was noted after approximately 30 seconds of closed reduction at- tempts; however, leg lengths appeared approximately equal. A pelvic radiograph was obtained at this time, which revealed displacement of the femoral component and an associated periprosthetic calcar femur fracture (Fig. 5). The patient was admitted for medical optimization and surgical planning. She returned to the operating room for HA revi- sion 72 hours after admission. The fracture was fixed and a cemented femoral component was placed (Fig. 6). The patient’s postoperative course was uneventful and she was discharged on postoperative day

5. She experienced no further complications and was full weight bearing by 4 weeks. She unfortunately died of unrelated health conditions ap- proximately 20 months after her hip surgeries.

Hemiarthroplasties are becoming much more prevalent as our soci- ety ages and is one of the most common treatments for femoral neck fractures in low-demand patients [10]. The dislocation rate of HA is ap- proximately 5% at 20 years [11]. Emergency medicine physicians must be able to recognize potential and preexisting complications associated with this procedure before attempting closed reduction.

Hemiarthroplasties have 2 designs: press-fit and cemented. Press-fit HAs are supported within the femoral canal by friction with the bone. The outer surface of the femoral component is designed for either on- growth or in-growth of bone that requires at least 8 to 10 weeks for some evidence of growth [10]. Press-fit HAs can also cause proximal femoral fracture at the time of implantation due to hoop stresses and may unfortunately go undetected until representation. After completion of bony on-growth or in-growth, the femoral stem is more stable within the canal. Cemented HAs are placed into the proximal femur with bone cement at the time of implantation. Press-fit and cemented HAs can be distinguished based on radiographic features (Fig. 7). Given the presen- tation of a dislocated press fit HA within 8 weeks of surgery, traction and manipulation under anesthesia must be titrated accordingly to prevent femoral component dissociation.

Hemiarthroplasties are implanted by a variety of surgical ap- proaches to the hip that often can dictate the direction of dislocation. Most of HAs are implanted through a lateral or anterolateral approach

0735-6757/(C) 2016

Fig. 1. Left, displaced femoral neck fracture (red arrow) sustained from a fall from standing. No other injuries sustained.

that requires incision of the anterior hip capsule [3]. The violation of the anterior capsule places the hip at increased risk for anterior dislocation if anterior hip precautions are not followed postoperatively. The poste- rior approach is another popular approach that requires incision of the posterior hip capsule. The violation of the posterior hip capsule places the patient at increased risk for posterior hip dislocation if posterior hip precautions are not followed postoperatively.

Fig. 3. Left hip radiograph bipolar HA with superior migration. The stem appears well fixed without any sign of fracture or hardware compromise.

Fig. 2. Postoperative radiographs showing a bipolar press-fit stem.

The direction of hip dislocation determines the presentation of the patient in the emergency department. A patient with a posterior dislo- cation most commonly presents with the affected leg flexed, adducted, internally rotated, and shortened (Fig. 8). Anterior dislocations present with the affected leg abducted, externally rotated, and shortened (Fig. 9). Recognition of the direction of dislocation dictates the tech- nique of reduction under conscious sedation (Fig. 10).

Closed reduction of a dislocated HA or THA is typically successful in the emergency department under conscious sedation. However, one cannot guarantee that this will be successful and the patient may ulti- mately require operative intervention to obtain reduction. One reason that reduction may be hindered is by entrapment from the surrounding musculature. Several reports have indicated entrapment of the femoral component by different muscles, namely, the psoas, rectus femoris, and gluteus muscles [12,13]. All reported cases required open reduction. This was likely the situation presented in this case, preventing closed re- duction and resulting in the displacement of the femoral component.

It is unclear when the discovered femur fracture occurred; it may have occurred during the Traumatic dislocation or during the Reduction attempt. This highlights the fact that even with proper technique, the bone and construct are at risk especially in an osteoporotic, elderly pa- tient. It is extremely important to recognize the type of HA implant (uncemented press-fit femoral component) before attempting a force- ful reduction especially in a potentially undermedicated patient. Emer- gency medicine physicians must remain vigilant for the direction of dislocation, date of surgery, and HA design before reduction to increase the likelihood of Successful reduction and prevent adverse outcomes.

This case provides a rare but potentially devastating complication after HA dislocation. It should serve as a reminder to approach

Fig. 4. Posterior hip dislocation reduction technique. While an assistant provides countertraction by stabilizing the pelvis, the hip and knee are flexed to 90? and internal rotation is performed until successful reduction is achieved.

Fig. 6. Left hip radiograph postoperative day 0 after revision surgery with conversion to a cemented stem. Note the cable to stabilize the calcar fracture.

these reductions with caution in the emergency department. If the reduction does not occur abruptly with appropriate maneuvers and moderate force, consider checking leg lengths and reevaluating the

Fig. 5. Pelvic radiograph revealing persistent dislocation of the left hip complicated by displacement and calcar femur fracture (arrow) of the press-fit, bipolar femoral component.

hip radiographically before further attempts. Closed reduction may not be possible and early recognition of this situation will limit unneces- sary damage and expedite the appropriate treatment.

Christopher R. Nacca, MD* Andrew P. Harris, MD John R. Tuttle, MD

Department of Orthopaedics, Brown University Alpert School of Medicine, Providence, RI, Island

*Corresponding author at: Department of Orthopaedics, Brown University Alpert School of Medicine, 593 Eddy St., Providence, RI 02903. Tel.: +1 401 444 4030; fax: +1 401 444 6243

E-mail address: [email protected] http://dx.doi.org/10.1016/j.ajem.2016.10.006

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    Fig. 7. Left hip radiographs demonstrating uncemented (A) and cemented (B) press hip hemiarthroplasties. Note the lack of a cement mantle distal to the stem (black arrow) compared with a present cement mantle (red arrow).

    Fig. 8. Typical presentation of a posterior dislocated prosthetic hip. The affected leg is

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    Fig. 9. Typical presentation of an anteriorly dislocated prosthetic hip. The affected leg is abducted, externally rotated, and shortened.

    Fig. 10. Anterior hip dislocation reduction technique. While an assistant provides countertraction by stabilizing the pelvis, the hip and knee are extended and axial traction is applied until successful reduction is achieved. Often allowing the legs to hang off the bed with the assistance of gravity will help in difficult reductions.

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