Evaluating and Treating Patients With a Recalled Exactech Knee Replacement: A Consensus Approach

History of Exactech Total Knee Arthroplasty Devices

Founded in 1985, Exactech, Inc. (Gainesville, FL, USA) sells a portfolio of upper- and lower-extremity joint replacement products and surgical instruments. The company introduced the Optetrak knee system—a bicondylar, nonanatomical, symmetric device—in 1994 [6] as an evolution of the initial posterior-stabilized (PS) knee design. It gained wide acceptance due to its liner modularity and the introduction of a mid-level constraint PS insert. The deepened and elongated femoral trochlea and improved patellar button design enhanced patellofemoral tracking [10]. Potentially due to the more constrained trochlear design, in 2006, Berti et al [3] reported the superiority of patellar resurfacing versus nonresurfacing in their clinical and biomechanical evaluation of the Optetrak device. A number of clinical follow-up studies established an overall excellent track record for the Optetrak knee system [1,2,16]. In a 2011 study of more than 420 knee joints, García-Crespo et al [10] reported good midterm results of the Optetrak system, with a 12-year revision-free implant survival rate of 91.3%. In another study, the survival rate for the Optetrak system was 97.2% at 10 years [5].

The Optetrak Logic was the next generation, released to the market in 2009. It incorporated modifications to the anterior surface of the tibial post and the corresponding femoral box to reduce edge loading on the polyethylene post and reduce impingement anteriorly. The effectiveness of the design modifications in reducing post damage was demonstrated by comparing retrieved Optetrak Logic tibial components to retrieved components of the predecessor Optetrak design [12]. The findings of a retrospective clinical study comparing the outcomes of patients who received 1 of these 2 knee replacement devices suggested the superiority of the newer design [4]. In a prospective cohort study, the Optetrak Logic implant was compared to other contemporary knee implants; although the results were generally good, no difference in patient outcomes was found between different designs [14].

Exactech introduced its latest update of the Optetrak design in 2017. Named Truliant, the new design retained many of the features of the previous Optetrak and Optetrak Logic knee systems, including the cam/post geometry and surface articulation, while reducing some of the femoral overhang noted with its predecessors. The Truliant also has a chamfer on the posterior surface of the polyethylene insert to aid in ensuring that the insert is fully locked into the tibial tray posteriorly [8].

The Exactech Recall

On August 31, 2021, Exactech initiated a voluntary recall of some of its polyethylene total joint arthroplasty products. This was followed on October 4, 2021, with the U.S. Food and Drug Administration (FDA) issuing a Class 2 device recall, which included all 3 generations of the Optetrak knee system [17]. According to the company, internal tests showed that approximately 80% of the tibial inserts manufactured since 2004 were packaged in out-of-specification vacuum bags that were oxygen resistant but did not contain a secondary barrier containing ethylene vinyl alcohol to further augment oxygen resistance. The lack of this layer can allow oxygen diffusion into the ultra-high molecular weight polyethylene (UHMWPE) insert, which could lead to increased oxidation of the material. Increased oxidation results in accelerated polyethylene wear with subsequent osteolysis that could lead to bone loss, aseptic loosening, and need for revision surgery [13]. In 2022, Exactech expanded the recall to include all knee, hip, and ankle arthroplasty polyethylene inserts packaged in non-conforming packages, regardless of label or shelf life [9,13].

In 2021, the Australian Orthopedic Association’s National Joint Replacement Registry confirmed increased revision rates for all Exactech Optetrak polyethylene component combinations compared to other total knee replacement systems, with a hazard ratio up to 5.85 at 1.5-year follow-up [2]. The latest study, which retrospectively analyzed a large cohort of almost 8,000 Optetrak Logic implants manufactured by Exactech, showed a short-term (2 years) revision-free survival of 98%, with a drop in the survival rate to 86% at 10 years [11]. More than half of the revisions (56.6%) were due to aseptic mechanical failure. Polymeric wear-related synovitis was detected in 91.4%, and component loosening was found in 3/4 of the revision cases. Isolated femoral implant debonding was found in 15.4%, isolated tibial implant debonding occurred in 1.9%, and debonding of both components was found in 3.8%.

The FDA and Exactech have established a detailed list of all lots of implant components affected by the recall. According to the company, this could include as many as 484 420 units worldwide [13,18]. Recognizing that an enormous number of devices (approximately 143 484 knee and ankle inserts) with defective packaging have been implanted since 2004 in the United States, the FDA and Exactech provided information for patients and physicians [7,9]. However, there are no guidelines for surgeons on how to manage affected patients. Since many patients at Hospital for Special Surgery (HSS) are affected by the recall, a taskforce was formed to develop standardized screening and treatment recommendations. The taskforce included Geoffrey Westrich, MD, Peter K. Sculco, MD, Thomas P. Sculco, MD, Elizabeth B. Gausden, MD, Brian P. Chalmers, MD and Friedrich Boettner MD, all orthopedic surgeons at the adult reconstruction and joint replacement (ARJR) service at HSS, as well as Timothy Wright, PhD, chief biomechanical engineer at HSS. The taskforce developed guidelines by consensus, and the guidelines received final review and approval by Mathias P. Bostrom, MD, chief of the ARJR service at the time.

Guidelines and Follow-Up Recommendations Developed

To aid in the management of patients affected by the recalled knee implants, the taskforce developed a diagnostic algorithm for physicians based on a patient’s current condition and symptoms, with a hierarchy of decision-making steps to ensure optimal treatment (Fig. 1). The guidelines provide general recommendations for screening and treatment arrived at by consensus on our taskforce for additional clinical and radiographic follow-up for these patients. Based on the severity of symptoms and the most recent radiographic findings, the care of an individual patient might vary.

Fig. 1.

Algorithm of the taskforce recommendations.

All patients with Exactech’s recalled knee replacement devices must be informed about the recall, with follow-up visits initiated. For this purpose, the company offers a corresponding patient letter [7].

For asymptomatic patients (those without a knee effusion and/or new onset pain on examination) and with routine radiographs that do not demonstrate osteolysis or aseptic loosening, follow-up should be scheduled every 2 to 3 years. More frequent follow-ups are recommended for patients who have either isolated imaging abnormalities (eg, a focal osteolytic area) or mild symptoms (eg, occasional pain or a small effusion at the knee).

For patients who report chronic or acute onset of symptoms such as persistent or increasing knee swelling, an immediate clinical evaluation and workup should be performed. Exactech offers covering out-of-pocket expenses that patients incur via a claim process.

Diagnostic Workup

Every patient should be thoroughly examined, including screening for excessive knee swelling (joint effusion) or new onset ligamentous instability. Standard radiographs should include anteroposterior (AP), lateral, and Merchant views. Radiographs should be carefully screened for the presence of osteolysis or implant migration and compared to prior radiographs. Typical locations for osteolysis include the medial and lateral femoral condyle, the medial and lateral tibia plateau, and the patella. A common radiographic finding is progressive osteolysis behind the anterior flange of the femoral component.

Any patient with suspicious findings on radiographs should undergo cross-sectional imaging. At our institution, magnetic resonance imaging (MRI) is often the next step because it provides superior assessment of synovitis, presence of polymeric debris, soft-tissue abnormalities (ligament competency), and osteolysis. Computed tomography (CT) imaging is a valuable alternative and provides excellent visualization of osteolytic lesions around both implants. In patients with negative cross-sectional imaging but with weight-bearing pain, a 3-phase whole-body bone scan can provide further information for the diagnosis of femoral implant debonding, which is difficult to detect on cross-sectional imaging.

Every symptomatic patient should undergo standard blood testing including C-reactive protein (CRP) levels to rule out periprosthetic joint infection. Should the serum marker exceed the standard references, aspiration of the joint is strongly encouraged to evaluate aerobic and anaerobic cultures and the synovial white blood cell count and neutrophil percentage. A synovial white blood cell count exceeding 3000 cells/µL with more than 80% polymorphonuclear granulocytes or a positive culture are suspicious for a deep implant infection.

Nonoperative Treatment

In patients with abnormal clinical and/or radiographic findings, the surgeon must carefully balance the risks of a revision surgery versus the risks of observation and progression of the osteolysis. Acute weight-bearing pain and the presence of significant osteolysis on cross-sectional imaging usually indicate the need for revision surgery. Corticosteroid injections and arthroscopic synovectomies to treat swelling and synovitis are usually not indicated, as neither of these interventions addresses the underlying polyethylene particulate wear that will progress if left untreated.

Operative Treatment: Isolated Liner Exchange

Limited indications exist for isolated liner exchange, but it may be considered in the following clinical scenarios.

Ligamentously Stable and Well-Fixed Implants

An isolated liner exchange could be considered for patients with stable flexion-extension gaps and well-fixed implants who present with knee effusions but without significant weight-bearing pain. Even if no evidence is found of implant loosening in the preoperative imaging, intraoperative implant stability must be confirmed at the time of surgery. We have seen numerous examples of debonded femoral components that have normal preoperative imaging but are easily removed at surgery. We believe that weight-bearing pain and/or decreasing flexion range of motion are often associated with femoral component debonding/loosening, so surgeons should proceed with caution when performing isolated liner exchanges in these patients.

We encourage recruiting experienced revision surgeons for assistance with these cases. Implant loosening identified at the time of surgery (usually involving the femoral component) should be treated with both-component revision. A planned, straightforward isolated liner exchange can quickly turn into a much more complex and difficult revision; such operations should only be performed by surgeons at institutions with ready access to equipment and implant inventories capable of managing both-component revision with potential for ligament insufficiency and bone loss.

Thorough Synovectomy/Debridement

Performing a thorough debridement with as comprehensive a synovectomy as possible, including the superior gutters and posterior knee, is essential and should be carried out to reduce residual polyethylene/particulate bioburden. Surgeons should be aware that the flexion and extension gaps, particularly the flexion gap, can change significantly after removal of reactive macrophage-laden synovial tissue.

Small Osteolytic Lesions

The treatment of small, isolated osteolytic lesions with bone grafting as part of an isolated liner exchange should be reserved for select cases. In general, we consider the presence of larger (>0.5 cm in diameter) osteolytic lesions and multiple areas of osteolysis to be an indication for both-component revision. The presence of significant osteolysis behind the femoral component is usually associated with femoral component debonding, and component revision should be planned in these cases. Thorough debridement of the posterior knee is greatly facilitated by removal of the femoral component. However, tibial osteolysis can be present without tibial component debonding.

All patients who have undergone an isolated liner exchange should initially be scheduled for at least annual follow-up examination to assess for resolution of the knee effusion and to confirm absence of osteolysis progression on radiographs.

Operative Treatment: Patella Revision

We have a low threshold to revise the patella button because the bearing surface of the patellar component is often severely damaged, and many cases have had significant osteolysis behind what appeared to be a well-fixed patella. When patella revision results in significant bone loss and inability to replace the removed patella button or it threatens the extensor mechanism, patella button retention and close follow-up examination may be warranted.

Operative Treatment: Both-Component Revision

Both-component revision should be considered for the following situations.

Implant Loosening

Regardless of whether the loosening of the implant was noticed on the preoperative imaging or intraoperatively (eg, in the context of a liner change), a loose implant should always trigger component revision. Although most cases present with isolated loosening of the femoral component, the taskforce recommends both-component revision [15] with a low-threshold for patella button revision [17].

Significant Osteolysis

Evidence of significant or progressive osteolysis on CT/MRI is a strong indication for prompt revision of both components to prevent catastrophic implant failure or progressive osteolysis that compromises the integrity of the collateral ligaments or patella tendon insertion.

Significant Bone Defects

Intraoperatively, bone loss is often seen to be worse than anticipated. For this reason, cross-sectional imaging (MRI and/or CT) is recommended in addition to conventional radiographs. For larger bone defects, cones or sleeves with bone grafting should be considered. Larger osteolytic lesions involving the femoral epicondyles might require a hinge if the insertion of the collateral ligaments is compromised.