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

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