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Bicompartmental Knee Arthroplasty: A Bone-sparing, Ligament-sparing, and Minimally Invasive Alternative for Active Patients

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Abstract

In the past, treatment of knee osteoarthritis has been limited to unicompartmental knee replacement or total knee arthroplasty (TKA). Neither option is well suited for the active patient with midstage osteoarthritis of the medial and patellofemoral compartments. Now an alternative treatment is available that targets the diseased area without sacrifice of normal bone or both the cruciate ligaments. Minimally invasive surgical techniques are easily used, which reduces tissue trauma and results in a quicker recovery than TKA. Bicompartmental replacement offers decreased pain, stability through normal ligament structure, and the retention of normal bone for patients with medial and patellofemoral osteoarthritis.

Osteoarthritis of the knee is very common and accounts for more than 350,000 knee arthroplasty procedures each year. Yet, most patients do not present with equal involvement of the medial, lateral, and patellofemoral compartments. For many, the most common finding is arthritic involvement of the medial and patellofemoral compartments. Traditional treatments use either unicompartmental or total knee replacement (TKR); neither of which is well suited for active patients with medial and patellofemoral arthritis. A revolutionary bicompartmental design is now available specifically to address the joint involvement of these patients with a monolithic device that resurfaces both the medial and the patellofemoral compartments, while leaving the lateral bone areas and cartilage intact. In addition to bone conservation, the anterior and posterior cruciate ligaments are preserved, resulting in more normal knee function. A minimally invasive surgical technique is well suited for this procedure and allows for a quicker recovery when compared to TKR. Treatment specifically targeted at the pathologic compartments without loss of normal bone and ligaments results in a rapid return to normal activity, increased stability, and decreased pain. Figure 1 shows a bicompartmental replacement and the graphic representation of the prosthesis.

Unicondylar knee replacement and patellofemoral joint devices are designed to treat only one compartment of the knee. Both devices allow for conservation of healthy tissue and bone, but the devices are designed to treat only the specific compartment and not to work together. Unicondylar knee arthroplasty of the medial compartment conserves bone and ligaments, which have been reported to result in a more normal gait, better quadriceps function, and better knee flexion than those treated with TKR.¹ However, success of this treatment is highly dependent on the accurate assessment of possible arthritic involvement of the patellofemoral compartment. Undetected pathology and disease progression to the patellofemoral compartment has been correlated with late failure of the unicondylar knee arthroplasty.^1,2 In contrast, patients with involvement of only the patellofemoral compartment can be treated with a patellofemoral joint device, but again, proper patient selection is crucial because disease progression to medial or lateral tibiofemoral compartments resulting in recurrent joint pain is not uncommon.³

The loss of the anterior cruciate ligament (ACL) and possibly the posterior cruciate ligament following TKR results in a change of knee kinematics not found in unicompartmental or bicompartmental arthroplasty. In addition, removal of all three compartments of the femur, regardless of arthritic involvement, may be responsible for higher pain scores and a longer recovery compared with unicondylar knee arthroplasty. Patient activity levels also should be a consideration with TKR in the event of future revision. Compared with unicondylar knee arthroplasty and TKR, the Journey Deuce bicompartmental device (Smith & Nephew, Memphis, Tenn) could be described as the ideal knee implant for patients with mid- to late-stage arthritis involving the medial and patellofemoral compartments. Journey Deuce is a durable device available in either low-wear oxidized zirconium for the high-demand patient or cobalt chrome for less active patients. The device uses a monolithic design that replaces only the diseased medial and patellofemoral compartments while sparing the lateral compartment and both cruciate ligaments. Retention of the cruciate ligaments maintains normal kinematics and proprioception. Because bone and ligaments are conserved, pain relief should be similar to unicondylar knee arthroplasty. Less pain and reduced tissue trauma help to speed recovery and a return of function. Conservation of bone also provides reference landmarks in the event of future revision. Journey Deuce is suited for the active high-demand patient. However, the Journey Deuce also benefits the less active patient, regardless of age. Contraindications for this bicompartmental arthroplasty include tricompartmental arthritis, rheumatoid arthritis, fixed flexion contracture, severe deformity, and functional ACL laxity.

Materials and Methods

The monolithic design of the Journey Deuce device resurfaces the medial and patellofemoral compartments of the femoral bone. The patellar portion of the monolithic construct has a trochlear groove for improved patellofemoral tracking throughout the range of motion (ROM). The patellofemoral surface functions with either a resurfaced or nonresurfaced patella. The medial femoral condyle articulates on a unicompartmental tibial base sized to provide the maximum coverage on the cortical shell of the resurfaced tibial plateau. Postoperative radiographs (Figure 2) demonstrate the monolithic design and positioning of the resurfaced patella.

Journey Deuce implantation is conducive with a minimally invasive procedure because the lateral area is not exposed. An incision of approximately 10 to 12 cm gives ample room for surgery yet minimizes exposure and tissue damage. Excision of the medial fat pad may aid in visualization of the joint. The first area resected is the medial portion of the tibial plateau. The extramedullary alignment tool is used to position the fixation rod and cutting guide for resection of the tibial plateau. Once resected, the proper size of the tibial base plate is determined. The flexion and extension balance is assessed using trial components.

When tibial preparation is complete, femoral preparation is begun by opening the femoral canal and inserting the intramedullary rod. The anterior femoral alignment is determined using the femoral alignment template and cutting block. When alignment is verified, the anterior femur is resected. The distal cut is determined using the variable angle alignment guide and distal cutting block in reference to the intramedullary rod. The angle is adjusted according to the transition point laterally. Pins are placed into one set of holes in the cutting guide for stabilization. Another set of holes allow for movement of the block proximally or distally. When the cutting block is aligned, the variable collet and valgus alignment guide can be removed to improve visibility. A medial distal femoral cut is performed to allow the final implant to sit at or just proximal to the native cartilage laterally.

When the medial distal and anterior cuts are made, the mediolateral position is determined according to the position of the posterior condyle. Reference lines on the cutting block are used to determine the width of the implant. The second landmark for the mediolateral position is the finger of the anteroposterior cutting block, and should be proximal to the transition point. Verification of the posterior resection level should be made using femoral shims. Resection is first performed on the posterior resection followed by the posterior chamfer. Next, the femoral cuts are made on the anterior resection and transition zone resection. A reciprocating saw may be useful in the resection of the transition zone cut.

When resection of the femur is complete, the patella may be resurfaced with an inset or round resurfacing component. After the femoral and patellar preparation is complete, trial devices are seated and the ROM verified. For proper device placement, it is critical for the transition area of the femoral trial to be equal to or recessed below the native cartilage. If not, additional distal cutting must be done.

The tibial base and femoral implant are cemented in place using pegs to locate and secure the device in position. When the cement has cured, the front-loading tibial insert is locked in position on the tibial base. Care must be taken to avoid excess cement on any component. Extruded cement may be hard to visualize in minimally invasive surgery and may result in difficulty seating the insert or future soft tissue irritation, impingement, or decreased ROM.⁴

An area that requires particular attention when implanting the Journey Deuce device is the transition zone between the trochlea and the lateral femoral condyle. This area should result in a smooth transition from the device to the bone surface of the lateral condyle.

Results

To estimate the utility of the Journey Deuce device, 100 consecutive patients older than 40 years (average age 63.7; range: 40-88 years) were observed for arthritic compartmental involvement. To determine pathology, a radiologist interpretation was made for each patient. Radiographic interpretation found that 73 of 100 patients had involvement of both the medial and patellofemoral compartments, but no lateral involvement. Identification of this subset of osteoarthritis patients supports the need for a treatment option between unicondylar knee arthroplasty and TKR.

Patients with medial and patellofemoral pathology were implanted with the Journey Deuce bicompartmental device by one surgeon (L.R.R) beginning with the first implant in October 2003. A total of 95 patients were implanted and followed for 33 months. Eighty-two of the 95 patients were discharged 2 days postoperatively. The average ROM for the group was 0° to 117°. Two weeks’ postoperatively, most patients were able to walk with only a minimal limp and without the aid of assistive devices. Patients had no patellofemoral pain or clunking sounds. Lateral joint line tenderness was not present. Blood loss was clearly less than that in the TKR patients, because none required a blood transfusion. Patients reported a high level of satisfaction following Journey Deuce implantation.

A special consideration in the treatment of arthritic knees is the increased expectation of the more active arthritic population, whether young or old. To adequately serve this population, TKR should not be the first option for midstage arthritic patients with involvement of the medial and patellofemoral joints. Patient satisfaction is crucial to the arthritic population and should be considered when determining the course of treatment. In 2001, Hawker et al⁵ analyzed eligibility requirements for knee arthroplasty. They found that no more than 15% of eligible patients with arthritis would consider arthroplasty. The major reasons patients refused surgical treatment were postoperative pain and disability. The advantages offered by a bicompartmental arthroplasty uniquely meet the demands for normal kinematics and proprioception that allows for a high level of patient satisfaction following arthroplasty and a reduced level of pain. Such devices can benefit younger patients by retaining both cruciate ligaments, thus maintaining stability to the knee. Elderly patients can equally benefit by the reduced pain and blood loss and therefore a much easier postoperative rehabilitation. In addition, bicompartmental arthroplasty has also been used as an alternative revision option for a patient with a loose unicondylar knee arthroplasty. Radiographs of the loose unicondylar knee arthroplasty with revision to a bicompartmental prosthesis are shown in the figures. Note the bilateral tricompartmental prosthesis in comparison (Figure 3).

Discussion

Minimally invasive surgery is a common procedure in TKA, and the same advantages apply to bicompartmental replacement. The minimally invasive bicompartmental replacement surgery results in limited surgical exposure, shorter recovery time, less blood loss, reduced hospital duration, and minimized scarring. The bicompartmental replacement has the added advantage of not having to access the lateral joint. Minimally invasive surgery has many advantages over the standard technique, but care must be taken to prevent potential problems with this type of surgical technique. The most common problems can be divided into two primary groups: iatrogenic injury and malposition of the knee.

Areas of limited visualization should be handled with utmost caution to prevent injury to vessels and ligaments. Frequent manipulations in both flexion and extension should be used to increase the visibility when the minimally invasive surgical technique is used. Also it is recommended in all minimally invasive surgical procedures to resect the proximal tibial and patella first before attempting the femoral component. When performing the distal femoral resection, the knee should be placed in at least partial flexion to allow space from the posterior capsule.

Alignment is of particular concern with any minimally invasive surgical technique because tibial resection into varus has been linked to an increased risk for failure. Particular care should be taken when placing the extramedullary guide to avoid placing the tibial cutting jig too far medially on the face of the anterior tibia. Rotation of the femur and tibia should be carefully aligned to ensure patellofemoral kinematics and femorotibial biomechanics.⁴

Conclusion

The typical osteoarthritic patient is no longer elderly with low activity levels. Patients suffering from arthritic knees are demanding devices that can meet higher expectations in regard to durability, a normal feel, and the elimination of pain regardless of activity. To achieve greater patient satisfaction, the device selection process can no longer be limited to options of either a minimal or maximal treatment. Medial and patellofemoral involvement is the norm for many active midstage arthritic patients, and the bicompartmental device is tailored to treat the pathologic area with the benefit of improved function and bone conservation. The active patient provided with earlier intervention may some day be the elderly inactive patient with need of revision to a TKR. The bone conservation of the bicompartmental design will provide for this transition should the need arise.

References

1. Berger RA, Meneghini RM, Jacobs JJ, et al. Results of unicompartmental knee arthroplasty at a minimum of ten years of follow-up. J Bone Joint Surg Am. 2005; 87:999-1006.
2. Ackroyd CE. Medial compartment arthroplasty of the knee. J Bone Joint Surg Br. 2003;85:937-942.
3. Levitan D. Patellofemoral knee replacement effective when following strict indication criteria. Orthopaedics Today International. 2006;9:8.
4. Berend KR, Lombardi AV. Avoiding the potential pitfalls of minimally invasive total knee surgery. Orthopedics. 2005;28:1326-1330.
5. Hawker GA, Wright JG, Coyte PC, et al. Determining the need for hip and knee arthroplasty: the role of clinical severity and patients’ preferences. Medical Care. 2001; 39:206-216.

Authors

Dr Rolston is from the Henry County Center for Orthopedic Surgery and Sports Medicine, New Castle, Ind; Dr Bresch is from Orthopaedic Surgery Specialists, Des Plaines, Ill; Dr Engh is from the Anderson Orthopedic Institute, Alexandria, Va; Dr Franz is from the Klinik für Orthopädie and Sportsmedicine, Siegen, Germany; Dr Kreuzer is from the Memorial Bone and Joint Clinic, Houston, Tex; Dr Nadaud is from the Knoxville Orthopedic Clinic, Knoxville, Tenn; Dr Puri is from the Northwestern University, Feinberg School of Medicine, Chicago, Ill; andDr Wood is from the University of Western Australia and Perth Orthopaedic Institute, Nedlands, Wash.

All authors of this manuscript are consultants for Smith & Nephew. Dr Rolston has received compensation from the sponsor in the past 12 months. Dr Kreuzer is a consultant for Stryker and has advisor roles to disclose with Tissuelink and Sanuwave. Dr Franz has leadership roles to disclose with the sponsor. Dr Engh has received compensation from Depuy in the past 12 months. He also has stock holdings to disclose with Alexandria Research Technologies and has received research grants from Inova.