Orthopedics

Feature Article 

Outcomes of Cementless Total Knee Arthroplasty in Patients With Rheumatoid Arthritis

Nirav Patel, MD; Chukwuweike U. Gwam, MD; Anton Khlopas, MD; Nipun Sodhi, BA; Assem A. Sultan, MD; Sergio M. Navarro, MD; Prem N. Ramkumar, MD, MBA; Steven F. Harwin, MD; Michael A. Mont, MD

Abstract

The objective of this study was to evaluate implant survivorship, clinical outcomes, postoperative complications, and radiographic outcomes of cementless total knee arthroplasty (TKA) in patients who have rheumatoid arthritis (RA). Patients who underwent a primary cementless posterior-stabilized TKA and who had RA were reviewed. A total of 126 TKAs in 122 patients who had a mean follow-up of 4 years were analyzed. Implant survivorship was calculated. Postoperative clinical and radiographic follow-up was performed at approximately 6 weeks and 3 months and then annually. Changes in range of motion and Knee Society scores were noted. Radiographic evaluation was conducted as part of the follow-up process. Implant survivorship was 99.2%, with 1 aseptic failure. At final follow-up, mean extension and flexion were 2° (range, 0°–10°) and 124° (range, 95°–140°), respectively. Mean Knee Society pain and function scores were 92 points (range, 80–100 points) and 84 points (range, 70–90 points), respectively. There were no surgical complications. No progressive radiolucencies, loosening, or subsidence were noted except from the single aseptic failure reported. This study reports excellent survivorship and clinical and radiographic outcomes of cementless TKAs in RA patients. Although the decision regarding whether to use cemented or cementless TKAs in these patients should be based on surgeon experience and patient characteristics, the recent advances in implant fixation of cementless TKAs indicate no salient contraindications for RA patients. [Orthopedics. 2018; 41(2):103–106.]

Abstract

The objective of this study was to evaluate implant survivorship, clinical outcomes, postoperative complications, and radiographic outcomes of cementless total knee arthroplasty (TKA) in patients who have rheumatoid arthritis (RA). Patients who underwent a primary cementless posterior-stabilized TKA and who had RA were reviewed. A total of 126 TKAs in 122 patients who had a mean follow-up of 4 years were analyzed. Implant survivorship was calculated. Postoperative clinical and radiographic follow-up was performed at approximately 6 weeks and 3 months and then annually. Changes in range of motion and Knee Society scores were noted. Radiographic evaluation was conducted as part of the follow-up process. Implant survivorship was 99.2%, with 1 aseptic failure. At final follow-up, mean extension and flexion were 2° (range, 0°–10°) and 124° (range, 95°–140°), respectively. Mean Knee Society pain and function scores were 92 points (range, 80–100 points) and 84 points (range, 70–90 points), respectively. There were no surgical complications. No progressive radiolucencies, loosening, or subsidence were noted except from the single aseptic failure reported. This study reports excellent survivorship and clinical and radiographic outcomes of cementless TKAs in RA patients. Although the decision regarding whether to use cemented or cementless TKAs in these patients should be based on surgeon experience and patient characteristics, the recent advances in implant fixation of cementless TKAs indicate no salient contraindications for RA patients. [Orthopedics. 2018; 41(2):103–106.]

Rheumatoid arthritis (RA) patients have a proliferative synovitis, which results in destruction of articular cartilage and bone.1 The knee is affected in 90% of patients who have chronic RA, and total knee arthroplasty (TKA) is one of the most successful ways to treat end-stage disease in these patients.2–8 As a result of RA, patients often have poor bone quality, synovitis, and disuse muscular atrophy. As such, cemented TKA has traditionally been recommended to provide initial stability of fixation. These patients are also prone to bone and soft tissue deformities, which can affect the initial and long-term durability of components.5,9

More recently, improved cementless designs have shown equal, if not better, results in terms of fixation and longevity when compared with cemented TKAs.2,10–16 However, there have been concerns about the initial fixation of cementless implants in RA patients.2 Rheumatoid arthritis is known to affect the properties of the bone, increasing unmineralized tissue and resorptive activity and thus leading to osteoporosis.17,18 In addition, commonly used medications in this patient population (nonsteroidal anti-inflammatory drugs, corticosteroids, and methotrexate) have been shown to impede bone in-growth into porous-coated implants.19,20 The biologic bond between the bone and metal, which is crucial to the success of these implants, may be suboptimal, increasing the risk of loosening and wear and ultimately contributing to poor long-term results.

The purpose of this study was to prospectively evaluate implant survivorship, clinical outcomes, postoperative complications, and radiographic outcomes in a large series of newer generation cementless TKAs in RA patients.

Materials and Methods

Patient Selection

Institutional review board approval was obtained prior to initiation of this study. The authors reviewed patients who had RA and underwent a primary cementless posterior-stabilized TKA at a single high-volume institution between June 2008 and June 2014. All RA patients during this period who had a TKA were consecutively treated with this cementless design. No patients were excluded because of subjective view of poor bone stock. A total of 126 TKAs in 122 patients were available for this study. This cohort had a mean follow-up of 4 years (range, 2–8 years). There were 88 women and 34 men, with a mean age of 67 years (range, 47–86 years) (Table 1).

Baseline Patient Characteristics

Table 1:

Baseline Patient Characteristics

Implant Information

Between June 2008 and June 2013, a cementless, beaded, Peri-Apatite (PA)-coated femoral component and cobalt-chrome tibial baseplate (Triathlon Total Knee System; Stryker Orthopaedics, Mahwah, New Jersey) was used. This porous-coated implant incorporated multiple layers of cobalt-chromium beads with a 1.34-mm porous thickness, a porosity of 40%, and a pore size of 0.45 mm as measured by mean intercept length. These beads were coated with PA, a highly crystalline form of hydroxyapatite, which provides a 3-dimensional coating rather than an onlay surface. The femoral component incorporates an open posterior-stabilized box with medial and lateral pegs, which aid in stability.

From June 2013 forward, the prosthesis used was a titanium non–PA-coated baseplate. It was designed using a 3-dimensional modeling and analytical technology (SOMA; Stryker Orthopaedics), which enabled more accurate anthropometric sizing. This was achieved using an extensive computed tomography scan-based database on the tibial baseplate pegs to improve fit and fixation. The system uses a delta keel and 4 pegs instead of screws, having identified the best areas for bone fixation.21

All patients underwent resurfacing of the patella. Between June 2008 and September 2014, a beaded, PA-coated patella was used. From October 2014 forward, a highly porous, coated, metal-backed component with 3 pegs was used.

Surgical Technique

All procedures were performed using a minimally invasive midvastus approach by a midline skin incision. The surgical technique was the same for all implants in this series, as previously described.21 Intramedullary guides were used for the femur. Extramedullary guides were used for the tibia. Cysts and bone defects were filled with autogenous bone from the bone cuts, sclerotic areas were drilled with a 2-mm drill bit, and the components were implanted. Postoperatively, patients were fully weight bearing with range of motion exercises as part of an accelerated physical therapy program. All patients were discharged with greater than 90° of flexion. Synovectomy was not performed, as studies have reported no advantage in routinely performing this adjunct during TKA.22,23

Clinical Evaluation

Postoperative clinical follow-up to evaluate patients occurred at approximately 6 weeks and 3 months and then annually. The outcomes used were range of motion, Knee Society scores (KSS) for pain and function,24 survivorship, and complications (surgical and medical). At their latest postoperative follow-up visit, all patients were progressing. No deaths had been recorded.

Radiographic Analysis

Radiographic follow-up included assessment of radiolucent lines between the bone–implant interface (loosening), general radiolucencies, reactive changes, and implant subsidence at regular clinic visits. Standing anteroposterior radiographs were used to measure the preoperative femorotibial angle. Based on this, there were 82 varus knees (mean, 7.7°; range, 0°–20°), 38 valgus knees (mean, 13°; range, 10°–30°), and 6 neutral knees (less than 5° of deformity). Rather than fluoroscopic positioning, radiographs were performed by 1 of 2 experienced technicians to maintain relatively consistent results.

Data Analysis

Statistical analysis was completed using SPSS version 22.0 software (IBM, Armonk, New York). Implant survivorship was calculated using Kaplan–Meier curves, with revision for any reason as the end point. P<.05 was considered statistically significant.

Results

Implant Survivorship

The overall implant survivorship was 99.2% at final follow-up (Figure). The 1 failure was an aseptic subsidence of a tibial component. This 72-year-old man developed pain and instability at 3 years postoperatively. Anteroposterior and lateral radiographs revealed tibial baseplate subsidence. The patient underwent revision TKA shortly afterward. The tibial baseplate was found to be well fixed to the bone in the subsided position, with no evidence of loosening. It was revised to a cemented tibial baseplate without further complications. At latest follow-up of 4 years, the patient was doing well, having a KSS of 90 points for pain and a KSS of 85 points for function.

Kaplan–Meier curve showing all-cause survivorship (99.2% at mean 8-year follow-up) of the cementless total knee arthroplasty implant.

Figure:

Kaplan–Meier curve showing all-cause survivorship (99.2% at mean 8-year follow-up) of the cementless total knee arthroplasty implant.

Clinical Outcomes

At final follow-up, the mean knee extension was 2° (range, 0°–10°) postoperatively. The mean knee flexion was 124° (range, 95°–140°) postoperatively (Table 2). At final follow-up, the mean KSS was 92 points (range, 80–100 points) for pain. The mean KSS was 84 points (range, 70–90 points) for function at the final follow-up (Table 2).

Postoperative Range of Motion and Clinical Outcomes

Table 2:

Postoperative Range of Motion and Clinical Outcomes

Postoperative Complications

There were no surgical complications. There were 2 (0.8%) medical complications, including 1 pulmonary embolism and 1 myocardial infarction. These were both treated successfully, with both patients recovering fully and having no further sequelae at the final follow-up.

Radiographic Outcomes

No adverse radiographic events (radiolucencies, loosening, or subsidence) were noted, aside from the single aseptic failure resulting in subsidence of the tibial baseplate mentioned above at the final follow-up.

Discussion

Rheumatoid arthritis patients commonly require TKA, which has traditionally been cemented to provide initial stability and long-term durability. With improved techniques and newer generation implants, cementless TKA has been gaining popularity. However, there have been controversies about whether a cementless design is appropriate for this cohort of patients, as they are predisposed to increased bone resorption and bone softening.17,18 In addition, some of the commonly used RA medications have been shown to potentially inhibit ingrowth of bone into porous implants. Therefore, the current authors evaluated outcomes in patients with RA who underwent a TKA using a newer generation cementless implant design. At a mean follow-up of 4 years, this newer generation cementless implant had excellent survivorship of 99.2% in RA patients, with excellent functional outcomes and minimal complications.

This study had several limitations. This was a single-center study, which may make the results less generalizable to the wider population. Future studies could therefore be multicenter with a larger patient cohort. The follow-up was short, preventing the authors from drawing conclusions regarding longer-term outcomes and survivorship. Nevertheless, this study provides promising preliminary results for this group of patients. The authors will continue to follow these patients and report their results.

Most of the published studies on this topic used older generation implants. There are limited prospective studies on newer generation cementless TKA implants in RA patients. Several older generation implant studies have shown good clinical outcomes with cementless TKA in RA patients (survivorship greater than 90% at more than 10-year follow-up).6–8 Armstrong and Whiteside10 examined 55 TKAs in an older RA population (mean age, 62 years), reporting a 96% survival rate at 7 years. There were 2 revisions for infection and failure of the cementless, metal-backed patellar component, but bone stock was preserved in both, allowing for successful revision. The pain (mean, 88 points) and function (mean, 64 points) KSSs improved by 56 and 28 points, respectively, from pre- to postoperatively. Another study25 involved 168 hybrid TKAs in severe RA with a cementless femoral component and cemented tibial/patellar components in 98 patients. At 4-year follow-up, there were no signs of loosening of the femoral component, proving results comparable with those of cemented TKAs.25 More recently, Buchheit et al26 examined 23 patients with RA undergoing 34 posteriorly stabilized TKAs. The survival rate was 97% at 6 years, with 1 revision for loosening of the tibial component. Other complications included 1 early infection, 2 knees with stiffness, 1 supracondylar femoral fracture, and 1 patellar fracture. The postoperative mean pain KSS was 83 points (range, 40–100 points). The postoperative mean function KSS was 74 points (range, 20–100 points).

In a study of 112 RA patients with 179 cementless cruciate-retaining TKAs, a 96.8% survival rate was reported at a mean follow-up of 10.1 years.2 Mean KSSs were improved from 47.5 and 43.6 to 91.2 and 82.3 for pain and function, respectively. However, this was a retrospective study using 3 different types of implants. A study using a novel Hi-tech Knee II (Nakashima Medical, Okayama, Japan) cruciate-retaining prosthesis in 32 RA TKAs reported a 96.9% survivorship at a mean 8-year follow-up.16 Unfortunately, numbers were small and only Japanese patients were included. Both studies used older generation implants.

Conclusion

In this study, cementless TKA in RA patients led to excellent short-term survivorship and clinical and patient-reported outcomes and minimal complications. Future studies should aim to prospectively compare cementless and cemented implants in this patient population. In addition, meta-analyses of the current literature may more clearly demonstrate the outcomes. The decision regarding whether to use cemented or cementless TKA in these patients should be evidence based, depending on surgeon experience and patient characteristics. However, given recent improvements in implant fixation, cementless TKA in RA patients may effectively relieve pain and improve function.

References

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Baseline Patient Characteristics

CharacteristicValue
Total knee arthroplasties, Total No.126
Patients, Total No.122
Age, mean (range), y67 (47–86)
Sex, No. (%)
  Male34 (28)
  Female88 (72)
Body mass index, mean (range), kg/m233 (20–52)
Follow-up, mean (range), y4 (2–8)

Postoperative Range of Motion and Clinical Outcomes

OutcomePostoperative Mean (Range)
Range of motion
  Extension2° (0°–10°)
  Flexion124° (95°–140°)
Knee Society score, points
  Pain92 (80–100)
  Function84 (70–90)
Authors

The authors are from the Rubin Institute for Advanced Orthopaedics (NP, CUG), Center for Joint Preservation and Replacement, Sinai Hospital of Baltimore, Baltimore, Maryland; the Department of Orthopaedic Surgery (AK, NS, AAS, PNR, MAM), Cleveland Clinic, Cleveland, Ohio; the Department of Orthopaedic Surgery (SMN), Baylor College of Medicine, Houston, Texas; and Mount Sinai Beth Israel (SFH), Center for Reconstructive Joint Surgery, New York, New York.

Dr Harwin was not involved in the peer review of this manuscript.

Dr Patel, Dr Gwam, Dr Khlopas, Mr Sodhi, Dr Sultan, Dr Navarro, and Dr Ramkumar have no relevant financial relationships to disclose. Dr Harwin is a paid consultant for, is a paid presenter for, and holds stock in Stryker. Dr Mont is a paid consultant for Stryker, DJO Global, Sage Products, TissueGene, OnGoing Care Solutions, Orthosensor, Johnson & Johnson, Pacira Pharmaceuticals, Cymedica, and Performance Dynamics Inc; has received research support from Stryker, DJO Global, TissueGene, OnGoing Care Solutions, Orthosensor, and Johnson & Johnson; receives royalties from MicroPort; and holds stock in Peerwell.

Correspondence should be addressed to: Michael A. Mont, MD, Department of Orthopaedic Surgery, Cleveland Clinic, 9500 Euclid Ave, A40, Cleveland, OH 44195 ( montm@ccf.org).

Received: September 07, 2017
Accepted: December 06, 2017
Posted Online: January 29, 2018

10.3928/01477447-20180123-05

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