36-year-old man with RA with bilateral knee pain and severe valgus deformities
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A 36-year-old man with seronegative rheumatoid arthritis presented to clinic for evaluation with a history of debilitating bilateral knee pain and deformity.
He was diagnosed with RA at 23-years-old and, since that time, had been on several disease-modifying antirheumatic drugs. He reported being able to perform activities of daily living and work as an automobile mechanic, both limited by pain and deformity. In addition, he was self-conscious about the cosmetic appearance of his knees due to the severe valgus. His pain was located over the medial and lateral joint lines. He had trialed nonoperative management for multiple years with corticosteroid injections, NSAIDs, physical therapy and activity modification with mild relief of his symptoms.
On exam, his knee range of motion was approximately 10° to 105° bilaterally. He was unable to achieve full passive or active extension of his right or left knee. He had a 25° right knee and 30° left knee fixed valgus deformity. Figures 1 to 4 are radiographs taken during his initial visit demonstrating severe tricompartmental osteoarthritis with valgus deformities of the right and left knee. In addition, though not typical for RA, there was extensive ossification of the capsular, tendinous and ligamentous tissues about the knees.
Source: Howard A. Chansky, MD; Arthur McDowell, MD; Pooja Prabhakar, MD
What are the next best steps in management of this patient?
See answer below.
Staged bilateral TKA
We recommended a staged bilateral total knee arthroplasty after extensive discussion of the risks and benefits, including the possibility of injury to the common peroneal nerve. He was interested in proceeding with surgery given his symptoms. His medication regimen was optimized as he was taking two immunosuppressants. His last infliximab infusion was scheduled to occur at least 4 weeks prior to surgery, and he was weaned down to only 5 mg prednisone per day. We had a long discussion regarding his medication regimen and his risk for infection. Given our discussion regarding the risk and benefits, he elected to proceed with a staged bilateral TKA.
In the OR, the right knee was taken through a passive range of motion while the patient was relaxed under general anesthesia and found to have a fixed 25° valgus deformity and lacked 10° of extension.
Due to the severe valgus deformity, we elected to approach the knee via a longitudinal lateral arthrotomy with a coronal plane Z-plasty of the lateral retinacular and capsular complex, originally described by Peter A. Keblish, MD. A longitudinal skin incision was made lateral to the tibial tubercle and over the lateral border of the patella. This was followed by creation of a full-thickness lateral skin flap.
Surgical procedure
We used sharp dissection to longitudinally incise the quadriceps tendon and then performed sharp dissection through the superficial lateral retinaculum in a posterior and distal direction until approximately 5 cm to 6 cm posterior to the lateral border of the patella. This dissection was swung anteriorly and distally lateral to the patellar tendon. Next, we dissected in an anterior and medial direction to separate the retinaculum into separate superficial and deep layers. The original plan was to mobilize a portion of the infrapatellar fat pad with the lateral soft tissue flap, but ossification precluded this. After performing this sharp dissection to split the retinacular layer in the coronal plane, we sharply incised the deep capsular layer adjacent to the patella. This resulted in two distinct layers: one superficial-anterior and medial; and the other: deep, posterior and lateral, deep, posterior and lateral. Upon closure, this allowed significant lengthening in the coronal plane of the lateral soft tissue structures. There was extensive heterotopic ossification enveloping the knee surrounding the patella, femur and the tibia. Throughout the case, we avoided hyperextension, varus stress and dissection in the posterolateral corner.
Upon excising all the heterotopic ossification, we were able to passively correct the knee to approximately 10° to 15° of valgus. We subperiosteally released the soft tissue attachments to Gerdy’s tubercle. With this maneuver, we were able to passively place the knee in approximately 5° of valgus. We were then able to flex the knee and mobilize the patella over the medial aspect of the femoral condyle. No quadriceps snip was necessary. We placed the intramedullary patella guide rod and made a +4 mm cut and made this in 5° of valgus. We cut the proximal tibia using the mid-medial third of the tubercle, the anterior tibia and the second ray as references. The proximal tibial anatomy was distorted due to bone loss and deformity and several tibial cuts removing an additional 2 mm of bone were made before we achieved full extension.
We sized the femur and used the trans-epicondylar axis and our flexion gap to help determine 3° to 5° of external femoral rotation. We made our anterior, posterior and chamfer cuts. There were symmetric flexion and extension gaps with the 10-mm trial spacer block. We then completed the box cut to accept the Persona revision femoral component (Zimmer Biomet). We then placed a tibial trial and there was laxity throughout the range of motion. However, we felt we had adequate soft tissue balance and central patellar tracking. We then made our patella cut and placed a patella button in a slightly medial position. We marked the rotation of the tibial component, which was over the approximate center of the tubercle. We removed the trials and exposed the proximal tibia.
After several trials of different tibial trays, we chose the tray that gave the best coverage. It was difficult to assess, given how much of the posterolateral tibia had been ground away by the valgus deformity. We fixed this to the proximal tibia and reamed for the stem and broached. We then made our cut to accept a 10-mm lateral augment. We assembled this trial and performed an additional trial with all the components into place. For ideal stability, we anticipated needing a varus-valgus constrained implant. We had full extension and approximately 110° of flexion with gravity. The patella tracked centrally. The tourniquet had been let down previously for 90 minutes. Before removing the trials, we elevated the leg and reinflated the tourniquet. We removed all the trials and assembled our actual components. We lavaged the knee and cemented the components into place. The cement was allowed to harden with the knee in full extension. We noted similar findings as with our trials and placed the final 10-mm constrained condylar polyethylene insert.
We irrigated and then placed the knee in moderate flexion for closure. The knee was closed in layers from deep to superficial. We used the infrapatellar fat pad, which was preserved on a pedicle with the posterior retinacular flap, to close the gap between the lateral soft tissues and the patella tendon.
The patient was allowed to weight-bear as tolerated and perform range of motion as tolerated. He was discharged after a brief admission to the hospital with aspirin for deep venous thrombosis prophylaxis, an outpatient physical therapy referral and a multimodal pain regimen.
Follow-up
The patient returned for his regularly scheduled postoperative follow-up appointments for an incision check at 2 weeks and routine exam at 6 weeks. His knee range of motion was 0° to 110° at 6 weeks. He was able to recover fully and underwent the same procedure on the contralateral knee 9 months later. He now walks without support, has minimal symptoms and is back at work full-time as an automobile mechanic.
Discussion
RA and other inflammatory arthropathies are now typically controlled by DMARDs and non-steroidal inflammatory medications. However, many of these inflammatory arthropathies, particularly if recognized late, can lead to severe joint destruction and deformity. Severe flexion and valgus contractures are often accompanied by posterior subluxation and external rotation of the tibia. They are often the result of bony collapse and/or soft tissue contracture. When flexion contractures are associated with severe coronal plane deformities, more constraint may be necessary for optimal outcomes. Previous studies have documented an increased incidence in posterior instability and recurvatum deformity in patients with RA undergoing a cruciate-retaining TKA. Those complications lead to an increased rate of revision. While important to minimize constraint, especially in young patients such as ours, we felt that our choice of a condylar constrained insert was necessary and not surprising given the chronicity and degree of deformity present preoperatively. In addition, due to the severity of his polyarticular RA, including involvement of his feet and ankles, he is likely to place lower demands on his knee replacements and we believe these constructs will be durable.
Another important consideration is neurovascular injury in these patients. Patients with a combined valgus deformity and flexion contracture are at higher risk for postoperative peroneal nerve injury. Throughout the case, we were careful to avoid knee hyperextension and excessive valgus and avoided placement of retractors in the posterolateral aspect of the knee. We also proceeded to correct the deformities in a stepwise fashion to minimize forced correction of the flexion or valgus deformities.
In summary, in this complex case of RA of the knees with atypical periarticular ossification and fixed severe valgus and flexion deformities, we obtained good early clinical results via careful preoperative planning, as well as stepwise bony resection and soft tissue releases through a lateral approach with coronal plane Z-plasty.
Key points
- Assess if the valgus knee deformity is correctable.
- Valgus knee deformities can be corrected with soft tissue balancing by releasing tight structures laterally and performing a lateral approach may be beneficial for exposure.
- Augments may be necessary for severe erosions or bone loss.
- Patients with a combined valgus deformity and flexion contracture are at high risk for postoperative peroneal nerve injury.
- References:
- Hwang YS, et al. Knee Surg Relat Res. 2016;doi:10.5792/ksrr.16.020.
- Laskin RS, et al. Clin Orthop Relat Res. 1997;(345):24-28.
- Ranawat AS, et al. J Bone Joint Surg Am. 2005;doi:10.2106/JBJS.E.00308.
- Scuderi GR, et al. J Arthroplasty. 2007;doi:10.1016/j.arth.2006.12.110.
- Xu J, et al. Knee. 220;doi:10.1016/j.knee.2020.02.012.
- For more information:
- Howard Chansky, MD; Arthur McDowell, MD; and Pooja Prabhakar, MD, can be reached at the department of orthopaedic surgery and sports medicine at the University of Washington in Seattle. Prabhakar’s email: prabhaka@uw.edu.
- Edited by Andrew Bi, MD, and Pooja Prabhakar, MD. Bi is a chief resident in the department of orthopedic surgery at NYU Langone. He will pursue a fellowship in sports medicine at Rush University Medical center following residency completion. Prabhakar is a chief resident in the department of orthopaedic surgery at the University of Washington. She will pursue a fellowship in foot and ankle surgery at Baylor University Medical Center following residency completion. For more information on submitting Orthopedics Today Grand Rounds cases, please email orthopedics@healio.com.
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