Case Title: Acetabular Revision Following Two-Stage Exchange Revision Hip Arthroplasty

 

 

Demographics

 

Age: 71 years Sex: Male BMI: 26.2

 

Relevant Past Medical History

 

Principal pathologies: Non-insulin-dependent diabetes, hypertension, deep venous thrombosis.

Previous surgical procedures: Right total hip arthroplasty 2008, left total hip arthroplasty 2011, inferior vena cava filter (Fig. 19.22).

Medication: Januvia, atenolol, Tylenol, Coumadin.

History of Presenting Complaint: 71-year-old male with primary left THA in 2011 evaluated in the emergency room four years after index procedure for L THA dislocation. Described having several months of nagging left hip pain and two weeks of acutely worse and progressive left groin pain exacerbated by weight bearing for which he was taking Tylenol PRN. Laboratory values included ESR 49 mm/h and CRP 19 mg/L. An aspiration of

the left hip showed 80,000 neutrophils and a differential of 92%.

 

Clinical Examination

 

Symptoms: Acute left anterior groin and pelvic pain and inability to bear weight on the left lower extremity.

Range of motion: The patient was unable to perform an active hip range of motion secondary to pain, subluxation, and dislocation of the hip with passive range of motion.

Main disability: Acute on chronic left groin pain and inability to bear weight on left lower extremity.

Neurovascular evaluation: Sensation intact to light touch over bilateral superficial and deep peroneal and tibial nerve distributions. Palpable, albeit weak, pulses bilaterally. Motor function intact with the exception of weak abduction.

 

Preoperative Radiological Assessment/Imaging

(Figs. 19.22, 19.23, and 19.24)

 

 

 

 

Fig. 19.22 Most recent routine follow-up PA pelvis, prior to emergency department presentation. Evidence of significant femoral peritrochanteric and pelvic periacetabular osteolysis

 

 

 

 

 

Fig. 19.23 AP pelvis taken in the emergency room; loose cup, with cup and head dislocation. Redemonstration of proximal femoral and periacetabular osteolysis

 

 

 

 

Fig. 19.24 AP left hip in the emergency room; loose cup, with cup and head dislocation. Redemonstration of proximal femoral and periacetabular osteolysis. Presence of heterotopic ossification and retained broken screw fragments in the posterosuperior acetabulum

Preoperative Planning

 

Diagnosis: Dislocated left total hip arthroplasty secondary to septic loosening and suspected corrosion and trunnionosis of the femoral stem (Figs. 19.23 and 19.24).

Possible treatment options: One-stage exchange versus two-stage exchange with an antibiotic spacer followed by revision total hip arthroplasty with acetabular reconstruction with either hemispheric cup, antiprotrusio cage, custom pelvic reconstruction, or structural allograft to address areas of deficiency.

Chosen treatment method: Two-stage exchange followed by revision THA with a press-fit hemispherical cup with screw fixation and periacetabular buttress plate.

Expected difficulties: Acetabular bone loss involving the posterior wall and fractured medial wall detected at the time of explantation and spacer insertion.

Strategies to overcome difficulties: Have multiple implants available at the time of surgery including hemispheric jumbo-sized cups and cages along with bone graft. Also, have instruments available to assist with the extraction of components and screw fragments. Need to plan for possible difficulty in removing a well-fixed femoral stem including removal instruments and fixation cables if an extended trochanteric osteotomy is required.

 

Surgical Note

 

Patient’s position: Supine.

Type of anesthesia: Spinal.

Surgical approach: Utilization of the prior lateral incision and direct lateral approach.

Main steps: The cement spacer was removed. The acetabulum and femur were examined. The acetabulum was found to have a deficiency of the posterior wall, and there was a fracture of the medial wall that was detected at the time of

 

spacer implantation. The acetabulum was gently reamed. Attention was then turned to the femur. The canal was debrided and irrigated.

Reconstruction techniques: A hemispherical socket was placed; however, in the presence of posterior wall deficiency, a buttress augment was utilized to support the socket. The cup was fixed with multiple screws, and demineralized bone matrix was placed behind the acetabulum. The augment and the acetabular components were adjoined with the use of cement (Figs. 19.25 and 19.26).

 

Intraoperative Challenges

 

Challenges and solutions: Posterior wall deficiency was resolved with tantalum trabecular metal buttress augmentation of the hemispherical cup.

Unanticipated problems and solution: Deficient bone stock led to challenges in securing buttress augment. This was resolved with application of cement to adjoin the cup and the augment. The cup was also secured with multiple points of fixation.

Thorough description of decision-making, including the reason for the final decision: Acetabular reaming revealed sufficient bone stock such that it was decided to avoid further bone loss associated with reaming to accommodate a jumbo-sized cup. It was decided to address posterior wall deficiency separately with a posterior buttress. A porous-coated multihole tantalum cup was selected as it was anticipated; multiple points of fixation would be needed to secure the cup. It was decided that porous tantalum offered the best potential for bone ingrowth and reduced chance of periprosthetic infection. Structural allograft was avoided due to an increased risk of recurrent infection and associated risk of bone resorption and collapse.

Postoperative Radiographs

(Figs. 19.25 and 19.26)

 

 

 

Fig. 19.25 AP pelvis with juxtaposed right-sided primary total hip arthroplasty with press-fit cup without additional screw fixation. Left side with cementless cup secured with multiple points of fixation. Trabecular metal augment functioning as a buttress to the cup

 

 

 

 

Fig. 19.26 Frog-leg lateral with redemonstration of the cementless cup with multiple points of screw fixation and trabecular metal augment

 

Postoperative Management

 

Chemoprophylaxis and anticoagulant treatment period: The patient was started on Coumadin post-op because of having had a history of prior DVTs.

Gait/limb loading until full loading: The patient was made toe-touch weight bearing for six weeks post-op.

 

Follow-Up and Complications

 

The patient has done well postoperatively except for developing a large hematoma because of uncontrolled anticoagulation. His INR was 8.5 at one point. The hematoma required evacuation. There have been no subsequent complications.

 

Discussion [27, 40–42]

 

Advantages of the applied method: The selected method of treatment offered the greatest preservation and potential restoration of host bone and biologic fixation. The increased elasticity and coefficient of friction of tantalum metal are associated with enhanced initial fixation and faster biologic fixation. This method also permits restoration of a normal hip center.

Disadvantages of the method: A disadvantage to this method of treatment includes the utilization of two discrete components lacking provisions for direct fixation to one another, therefore requiring supplemental means of adjoinment. In this setting, cement was used to adjoin the cup and the augment and may allow an additional interface for failure.

Alternative evidence-based techniques for the case: An alternative method of reconstruction would be using an antiprotrusio cage or a cup-cage construct.

Why is the chosen technique better for this case? Using a routine sized cup and an augment preserved host bone and allowed for potential restoration of bone stock with supplemental bone grafting. The use of an augment allows selection

of sizes and shapes to address present defects specifically. It avoids creating a high hip center as can occur with the utilization of jumbo cups. And as opposed to using a structural allograft, the selected reconstruction is technically less difficult and without the risk of associated complications. Indications and contraindications for your technique: Bone stock such that there is a minimum of 50% host bone contact is required to use a hemispherical cup. Augments are best applied in the setting of contained defects. Pelvic discontinuity would be a contraindication to hemi-

spheric cup use.