Intraprosthetic Dislocation of a Dual Mobility Bearing After Hip Dislocation

Intraprosthetic Dislocation of a Dual Mobility Bearing After Hip Dislocation

Alexander Sah, MD

 

History:

This pleasant 79-year-old female had a series of problems after a metal-on-metal right hip replacement was done elsewhere in 2004. Due to elevated serum metal ion levels, the hip was revised in 2014 to a 28x48mm dual mobility bearing. Per the operative report, it was recognized by the recovery room X-ray that the incorrect head size was used, as the acetabular component inner diameter was actually 38mm. She was taken back to the operating room the same day for revision to the correct 28x38mm dual mobility system. Subsequently, hip instability ensued, and she had two hip dislocations after surgery. They were treated by closed reduction. She notes she was seen by her surgeon in early 2015, but no X-rays were taken. On a pain scale, the hip is rated a 5/10 and is intermittent. The pain is particularly bad when walking and going up stairs. She has been in physical therapy for 3 months without any improvement. She complains of stiffness, instability, limping, and pain. She notes grinding, catching, and instability of the right hip. She is referred for revision consultation.

Preop:

AP pelvis radiograph shows eccentric femoral head position within the acetabular component.
Figure 1

The patient has a well-healed surgical incision. No masses palpated and no swelling was present. She has a noticeable Trendelenburg gait. Due to discomfort, she has limited hip range of motion. There is no detectable subluxation or crepitation with hip motion. X-rays reveal eccentric femoral head position within the acetabular component (Figure 1).

The acetabulum is in excessive abduction, and there is osteolysis adjacent to the acetabular component. Frog-lateral view shows eccentric femoral head position and lysis adjacent to the acetabular component (Figure 2). On closer inspection, there is a shadow lateral to the hip joint with defined margins, suspicious of the mobile polyethylene liner or a fractured fragment of it (Figure 3). Preoperative evaluation with ESR and CRP was negative for infection.

Frog-lateral X-ray shows eccentric head position and lysis adjacent to the acetabular component.
Figure 2
Closer inspection suggests an outline of the polyethylene mobile liner or a fractured fragment of it.
Figure 3

Surgery:

Intraoperative photograph of the mobile polyethylene liner anterior to the femur.
Figure 4

Upon exposure through the fascia, a small amount of clear fluid was encountered. The hip joint was mobilized to expose the posterior hip, and a foreign body was noted anterior to the femur. Exposure of the object revealed the mobile polyethylene bearing lodged between the anterior femur and the surrounding soft tissues (Figure 4).

With this intraprosthetic dislocation, there was disassociation of the femoral head from the mobile polyethylene liner. This complication is unique to dual mobility hip articulations. The mobile liner was becoming enclosed within the soft tissue, and a pocket formed. It migrated from the posterior aspect of the hip, around the side of the femur, to the front of the hip joint. It was removed and involved scar tissue. Tissue samples were sent for cell count and culture, which eventually returned negative for infection.

Postoperative X-ray of revision hip arthroplasty.
Figure 5

The posterior approach to the hip was performed, and the femoral head was visualized to be eccentric in the acetabular component and articulating superiorly. The femoral head was exposed and removed with protection of the neck taper. The acetabular component was then removed with an explant system and revised. The lytic areas were filled with bone graft prior to cup placement. A metal on polyethylene articulation was used (Figure 5).

The patient’s postoperative pain management included a multimodal approach that combined toradol, acetaminophen, and a periarticular injection of liposomal bupivacaine. The exparel medication was expanded to 100cc to have more volume to disperse throughout the tissues. The patient had an intolerance of narcotics, and was therefore relying on non-opioid pain management. She was able to ambulate comfortably the day of surgery and was discharged home safely the following morning.

Postop:

The patient’s pain and stability were improved immediately after surgery. She had an uneventful postoperative course. Her limp improved with continued hip abductor strengthening. She had no episodes of instability. She subsequently required revision of the metal-on-metal hip on her opposite side, as her serum metal ion levels remained elevated prior to revision. She had pelvic lysis and metallosis and damage of her soft tissues at time of her left hip revision.

 

Failure of a metal-on-metal hip replacement: An unusual and severe case of corrosion

Failure of a metal-on-metal hip replacement: An unusual and severe case of corrosion

Alexander Sah, MD

History

The patient is a 79-year-old female with a 5 year history of R>L hip pain. She had anterior hip replacements done elsewhere about 10 years ago. Her gradual right hip pain has worsened over the past year. She now has sharp pain in the groin and at the side of the hip. She also has a worsening limp and depends on a cane for ambulation. She has tried injections, physical therapy, and requires norco for pain control. She has failed these nonoperative treatments, and is referred for revision consultation.

Preop

The patient has a well-healed surgical incision. She has a noticeable Trendelenburg gait. X-rays reveal a metal-on-metal hip replacement with satisfactory component alignment and fixation. Her right greater trochanter is essentially absent, from presumed osteolysis (Figure 1). Preoperative evaluation with ESR and CRP was negative for infection. Metal cobalt and chromium ion levels were significantly elevated. Of note, there is an insufficiency fracture of the greater trochanter seen on the opposite left side, also presumed to be due to corrosion and lysis.

Figure-1a
Fig 1A
Figure-1b
Fig 1B

AP pelvis shows lysis of nearly the entire right greater trochanter. A fracture of the left greater trochanter is also visualized.

Surgery

Upon exposure through the fascia, a copious amount of thick discolored material was encountered (Figure 2). Material was sent for culture, which eventually returned negative for infection. Evaluation of the proximal lateral femur revealed severe osteolysis, with cortical defects laterally (Figure 3). The entire trochanter was essentially dissolved into the thick material previously removed.

Fig 2
Fig 2 - Corrosion and osteolysis byproduct encountered upon hip exposure.
Fig 3
Fig 3 - Photograph showing extent of osteolysis and greater trochanter deficiency.

Exposure of the hip was performed and the hip dislocated. There were three areas of potential metal corrosion or metal wear. First, the backside of the metal acetabular liner was at risk due to a prominent screw head. However, there were no signs of wear at the cup-liner interface. Second, there was also no appreciable damage or wear at the liner-head articulation. Instead, at time of femoral head removal, there was significant corrosion (Figure 4).

Figure-4a
Fig 4A
Fig 4B
Fig 4B

Severe corrosion discovered at the head-neck taper.

Postoperative film with constrained liner placed.
Fig 5 - Postoperative film with constrained liner placed.

An extensive and thorough debridement was performed. The femoral stem was well fixed and retained. The taper was cleaned and a ceramic femoral head with a titanium sleeve placed. Due to the amount of abductor deficiency, and the absence of lateral proximal femur to act as host bone attachment for a potential allograft, a constrained liner was used (Figure 5).

With the extensive debridement and the amount of soft tissue damage from the corrosion process, pain management was dependent on liposomal bupivacaine injected throughout the surgical site. The exparel medication was expanded to 100cc to have more volume to disperse throughout the tissues. Revision arthroplasty procedures can benefit from having more volume of liposomal bupivacaine to optimize tissue infiltration and anesthetic overlap. A multimodal pain management protocol was also used, which allowed the patient to ambulate the day of surgery, and to be discharged home comfortably the following morning.

Postop

The patient’s pain improved almost immediately after surgery. She had an uneventful postoperative course. Her limp is mildly improved, but she understands that her abductor deficiency will persist because of the damage to her trochanter and abductors. She is relieved to have the source of her corrosion resolved, and to be able to now maximize her outcome with therapy. She is also scheduled for revision of her opposite left metal-on-metal hip replacement, which has a less severe case of corrosion.

Tibial Component Loosening and Bone Loss in a Patient with Chronic Pain

Tibial Component Loosening and Bone Loss in a Patient with Chronic Pain

Alexander Sah, MD

History

The patient is a 75-year-old female who underwent right total knee replacement in 1998 by her local surgeon. She did well until 4 years ago when she began to have knee pain. Radiographs indicated loosening of the tibial component (Fig 1). Evaluation at the time revealed that no infection was present. She was informed of the findings and component revision was recommended. Due to medical and social reasons, the patient chose not to have revision surgery. In particular, she had multiple lower spine surgeries and now requires chronic pain medications for her back pain. Radiographs show progression of loosening over time (Figs 2, 3). She now presents 4 years after her initial consultation.

Lucencies are visible under the medial and lateral aspects of the tibial component at time of initial presentation.
Fig. 1
Lucencies are progressive and varus subsidence of the tibial component is evident on subsequent xrays 1 and 2 years later.
Fig. 2
Lucencies are progressive and varus subsidence of the tibial component is evident on subsequent xrays 1 and 2 years later.
Fig. 3

Preop

At this stage, the patient has increased pain and leg deformity. Her leg alignment is in a greater degree of varus alignment. She realizes that her deformity is worsening as it affects her walking ability. She requires a walker to ambulate and can hardly perform her activities of daily living. On physical examination, her range of motion is from full extension to 120 degrees and she has expected instability to varus-valgus stress. Radiographs show significant leg deformity and tibial component loosening (Figs 4a, b, c).

AP radiograph shows tibial component loosening and bone loss due to component medial collapse.
Fig. 4a
Lateral radiograph reveals bone loss with component subsidence.
Fig. 4b
Standing full-length view illustrates overall limb varus deformity.
Fig. 4c

Surgery

Intraoperative photograph showing extent of tibial defect after component removal.
Fig. 5

At the time of her revision surgery, the tibial liner cannot be removed because the interface with the tibial component is sunken within the tibial cortex. The femoral component is removed with preservation of as much host bone as possible. When exposure of the proximal tibial is achieved, the tibial component and liner are able to be extracted as one piece because it is so loose. It is nearly completely subsided below the tibial cortical rim. The resulting tibial bone defect is significant (Fig 5). There is essentially only a shell of medial cortical bone remaining. The majority of the tibial metaphysis has eroded.

Intramedullary preparation of the tibia is performed to achieve press-fit of a tibial stem.  It is also used to make a proximal tibial resection to maximize bone support of the tibial tray. Because of the size of the defect, a trabecular metal tibial augment is prepared for with reamers and trial broaches (Figs 6a, b). Improved bone support is achieved with the lower cone portion of the augment, to add to the cortical rim support. After trialing of the components, a constrained liner is used due to the laxity of the collateral ligaments.

Examples of trabecular metal coupled cone augment attached to bottom of revision tibial component.
Fig. 6a
Examples of trabecular metal coupled cone augment attached to bottom of revision tibial component.
Fig. 6b

Postop

Due to a history of spinal fusions, the patient underwent general anesthesia rather than an epidural/spinal. She has chronic pain due to her back surgeries and so she took norco and levorphanol prior to surgery. Multimodal pain management was even more important given her relative resistance to narcotics. Intravenous acetaminophen was used intraoperatively and long-lasting liposomal bupivacaine injections were performed at the conclusion of the surgical procedure. Intravenous ketoralac was also used post-operatively. The patient was able to walk a short distance the day of surgery and was safely discharged home two days after surgery (Figs 7a, b). In addition to her usual narcotic dosages, her pain was well controlled with the described medications. She had much less pain and improved ambulation nearly immediately after surgery.

AP radiograph of revision total knee with tibial coupled cone obtaining additional tibial metaphyseal support.
Fig. 7a
Lateral radiograph of revision total knee with tibial augment.
Fig. 7b

An Unusual Failure of TKA

An Unusual Failure of TKA: Surgical Considerations and Pain Management in the Revision Setting

Alexander Sah, MD

History


A pleasant 61-year-old female presents with a 2 year history of left knee pain. She had previously undergone uncomplicated left total knee replacement at an outside institution. She reports that she was doing well until she fell and broke her left hip in 2012, which was treated locally to her. She feels she has not walked well since that injury, and that her left knee symptoms worsened two years prior to presentation. She does not recall specific trauma. Her orthopaedic surgeon evaluated her, but no diagnosis was made. Overall, the pain has worsened in the past 3 months.

On a pain scale, the knee is rated an 8/10 and is constant. The pain is particularly bad with standing, walking, going up or down stairs, and twisting. The pain is located on the inside and front of the knee. The pain is described as sharp and she also complains of swelling, instability, and limping. She requires Tramadol for pain and other conservative treatment has included activity modification and knee bracing. She uses a walker for ambulation and is mostly housebound. She denies fevers, chills, or signs of infection.

Her past medical history is significant for depression, fibromyalgia, atrial fibrillation, kidney disease, and coronary artery disease. She takes eliquis for anticoagulation.

Preop


Patient is 5’3” and 235lbs, BMI of 41.6, in no acute distress. She is in a wheelchair and is unable to walk without a walker. She has a well-healed midline knee incision. The leg alignment is valgus, with moderate laxity to valgus/varus stress. There is a trace effusion with tenderness to palpation at the medial and lateral joint lines. Her passive knee range of motion is from 0-110 degrees, but there is a 15 degree active extension lag. Due to the size of the leg, it is difficult to assess anterior and posterior knee stability. Her motor, sensory, and vascular exams are intact distally.

Radiographs reveal an absence of space between the components on the AP view.

Full length standing AP film.
Full length standing AP film.
Preoperative AP film shows loss of space between the femoral and tibial components.
Preoperative AP film shows loss of space between the femoral and tibial components.

Her patella is tracking centrally.

Figure 3. Preoperative merchant view.
Figure 3. Preoperative merchant view.

A lateral knee X-ray shows a femoral component in an extended position with the anterior flange underneath the anterior femoral cortex.

Figure 4. Preoperative lateral film shows disassociation of the liner, with the femoral component in extension and notching the anterior femoral cortex.
Figure 4. Preoperative lateral film shows disassociation of the liner, with the femoral component in extension and notching the anterior femoral cortex.
Figure 5. Close-up image of the liner dislocated anterior to the tibial component.
Figure 5. Close-up image of the liner dislocated anterior to the tibial component.

There is more cement present adjacent to the femoral prosthesis than expected, suggesting a prior bone defect. The liner is seen disassociated from the tibial tray and dislocated anteriorly.  The need for revision surgery was discussed with the patient. She understands that the dislocated liner requires revision. We discussed that while it is tempting to replace the liner only, there is a possibility that it may fail again if nothing else is revised. In addition, the malpositioned femoral component places her at risk for continued knee failure, or possible periprosthetic fracture. Furthermore, the suspected bone defects filled with prior cement may require additional stems or augments at time of revision. We also discussed the challenge of managing her postoperative pain given her history of fibromyalgia, pain medication use, and limitations due to existing kidney disease.

Surgery


Preoperative workup was negative for infection by ESR and CRP, and intraoperative synovial fluid analysis, frozen section, and cultures were also negative. Upon exposure of the knee joint, the liner was protruding anteriorly. The liner was severely worn posteriorly. The suprapatellar pouch and medial and lateral gutters were re-established and debrided of inflamed synovium from poly debris. The femoral component was then exposed and its placement in extension was confirmed. The component was removed with care to preserve as much host bone as possible, but there was a large defect anteriorly from the notching of the index procedure and after removal of the prior cement. The tibia was then exposed and removed. There was significant lysis and loss of metaphyseal bone, which was more than expected based on the preop films. The cortex of the tibia was mostly intact and reasonably supportive.

The tibia was prepared for an intramedullary stem with hand reaming. A proximal tibial resection was then performed to establish proximal bone support. Because of the extent of metaphyseal bone loss, the tibia was prepared for a trabecular metal coupled tibial cone augment.

 

Figure 6. Trabecular metal coupled tibial cone fixed to tibial baseplate with stem extension.
Figure 6. Trabecular metal coupled tibial cone fixed to tibial baseplate with stem extension.
Figure 7. Close-up of tibial cone attached to tibial baseplate.
Figure 7. Close-up of tibial cone attached to tibial baseplate.

This provided improved proximal support of the component, maximizing contact to host bone. The femur was then prepared for a stemmed constrained component to bypass the anterior bone defect. Trial reductions were performed and there was appropriate knee motion and stability. A hybrid technique was used that cemented the components into place and a press-fit was used for the stems.

Figure 8. Postoperative AP film showing components with stems and coupled tibial augment.
Figure 8. Postoperative AP film showing components with stems and coupled tibial augment.
Figure 9. Postoperative lateral film.
Figure 9. Postoperative lateral film.

The tibial cone can be placed with or without cement, but was cemented in this case because of the quality of the host bone.

For pain management, intravenous Tylenol was used preoperatively. No NSAIDs were used because of her kidney and anticoagulation contraindications. A periarticular injection of Marcaine with epinephrine was performed for short-acting pain relief, and to possibly minimize bleeding. Liposomal bupivacaine was first injected throughout the posterior capsule, medial and lateral gutters, and periosteum. Because of the size of the patient and the revision exposure, 100ml of diluted injection was used; a large volume allows optimization to create as large of a field block as possible. A 22-guage needle was used to maximize infiltration so that the injection stays within the tissue. Finally, the remaining injection was used in the soft tissues and skin prior to closure.

Postop


The patient tolerated the surgery well. Her pain was well controlled and she was able to ambulate the day of surgery. She had an unremarkable hospital course. She was discharged home the second day after surgery. At her two week appointment her incision was healing well, her pain was much improved compared to the pain she felt pre-surgery, and she was ambulating with a cane. At her 6 week appointment she was taking no pain medications and was walking without an assist device.