Six total knee arthroplasties in five patients were revised because of persistent limited motion after the primary arthroplasty. All of the revised implants were of an appropriate size and not malpositioned. No cause of stiffness was identified other than soft tissue contracture. Four of the components were posterior cruciate retaining and two were posterior cruciate substituting. Heterotopic bone formation was observed in two knees before the revision surgery and five knees after the revision surgery. Arc of motion was increased from 36 °(range, 20 °–70 °) before revision surgery to 86 °(range, 70 °–110 °) after revision surgery. What triggers the proliferation of extensive scar tissue formation in patients with arthrofibrosis is not clear. Some patients may be predisposed to this condition or may have it develop as a response to the surgical trauma and postoperative rehabilitation. However, when arthrofibrosis does develop after total knee arthroplasty, some improvement in motion and pain can be achieved with revision surgery.
Many patients achieve satisfactory range of motion (ROM) after total knee arthroplasty. 1 If postoperative motion is limited, treatment with manipulation can facilitate participation in physical therapy exercise programs to obtain adequate flexion.
2,5Occasionally, limited motion persists and causes significant functional impairment that requires operative treatment. Williams et al 19 reported improvement in motion in nine patients with limited flexion after posterior cruciate retaining total knee arthroplasty who were treated with arthroscopic posterior cruciate ligament release and manipulation. However, two (22%) of the patients required revision total knee arthroplasty. Nicholls and Dorr 13 reported satisfactory results in 11 of 12 patients who had revision of a total knee arthroplasty for stiffness. The cause of limited motion was malpositioned components in eight of the patients. The current authors have observed that stiffness can occur after posterior cruciate retaining and substituting total knee arthroplasties that are well aligned with appropriate sized components. This study was conducted to review the pathologic findings and results of surgical treatment for arthrofibrosis after total knee arthroplasty.
MATERIALS AND METHODS
This study was based on a review of the clinical, radiographic, and pathologic findings of six knees in five consecutive patients who required revision total knee arthroplasty because of limited motion after primary total knee arthroplasty. All of the patients had an underlying diagnosis of osteoarthritis and were treated with a prolonged course of physical therapy after the primary total knee arthroplasty. Revision total knee arthroplasty was offered to patients who presented with soft tissue contracture that impaired knee function and who were unwilling to accept the limitations associated with stiffness. The revision operations were performed by one surgeon. Minimum followup was 2 years.
Patients were included in the study if the revision surgery was performed because of complaints of stiffness and pain. Patients who had revision surgery performed because of pain but did not have limited motion were excluded from the study group. Patients who had revision surgery performed because of mechanical failure of the components, wear, or prior infection also were excluded. Included were only well-aligned knees with appropriate-sized components in which no cause of stiffness was identified other than soft tissue contracture. Patients with an underlying diagnosis of inflammatory arthritis were excluded.
All knees were exposed through a medial parapatellar approach with extended tibial tubercle osteotomy. Scar tissue was excised from the suprapatellar pouch, extensor mechanism, and medial and lateral gutters. The tibial polyethylene insert and femoral component were removed, leaving the tibial baseplate and patellar components in place. The posterior cruciate ligament, if present, and scar from the medial and lateral posterior compartments were excised. The femur was revised using a posterior stabilized implant. A revision femoral component was chosen of the same size or slightly smaller than the removed component to provide a wider flexion space and potentially improve knee flexion. A tibial posterior stabilized insert was chosen of appropriate thickness to permit approximately 5° hyperextension and full flexion of the knee without dislocation of the femoral component over the tibial post.
Postoperative rehabilitation was the same as that used for routine primary total knee arthroplasty. Constant passive motion was started on the day of surgery and increased daily within the patient’s pain tolerance. Weight Bearing activity was not restricted. A knee immobilizer was used during ambulation until the patient could actively perform straight leg raise against gravity and then it was discontinued. Physical therapy was performed daily during the inpatient hospitalization and continued on an outpatient basis for approximately 3 months.
Heterotopic bone formation was quantitated using the system of Harwin et al. 8 Heterotopic bone was assessed on lateral radiographs obtained within 1 week before surgery and at the most recent followup. Knee ROM and Knee Society score 9 were recorded before surgery and at the most recent followup. Radiographs obtained before the primary arthroplasty were not available for five of the six knees so it was not possible to assess whether the initial components were excessively large or thick.
Representative soft tissue specimens were obtained from the patellofemoral and posterior compartments. Sections were stained with hematoxylin and eosin and examined using light microscopy.
To determine if the pathologic features of the periarticular soft tissue in patients who had revision surgery for stiffness were different from those for patients who had revision surgery for other reasons, histologic specimens were obtained from a control group of a consecutive series of six knees in six patients who had revision total knee arthroplasty performed for reasons other than stiffness. Representative soft tissue specimens were obtained from the patellofemoral and posterior compartments.
All five patients in the study group were female with a mean age of 65.7 years. Four knees were right and two were left. Four of the revised knee arthroplasties were posterior cruciate retaining and two were posterior cruciate substituting (Table 1). One patient (Patient 5) presented with right knee pain and ROM from 20° to 50° 2 years after primary cruciate retaining total knee arthroplasty. The knee was revised successfully and the patient achieved relief of pain and improvement in motion to 0° to 85°. Degenerative arthritis in the contralateral knee then became sufficiently symptomatic that primary left total knee arthroplasty was performed. To minimize any possible causes of stiffness in the left knee, a primary posterior stabilized prosthesis was used and full ROM was obtained during the operation. The patient achieved flexion from 10° to 85° by the time of her discharge from the hospital but lost motion despite the use of home constant passive motion, daily physical therapy, and adequate pain control with oral analgesics. Two months after the operation, flexion was 10° to 45°. Manipulation was performed using a continuous epidural anesthetic. The patient remained in the hospital for 4 days to receive inpatient physical therapy while the epidural catheter was used to facilitate pain control. At the time of discharge, knee motion was 0° to 90°. Despite continued outpatient physical therapy and home constant passive motion, flexion was limited from 5° to 65°, 3 months after arthroplasty. The patient was readmitted and an epidural catheter was placed to facilitate inpatient physical therapy. The patient remained in the hospital 1 week and achieved motion from 5° to 85° by the time of her discharge. Despite continued outpatient physical therapy and use of oral narcotics for pain control, 1 year after the operation, knee motion was limited from 10° to 30° flexion. Grade 1 heterotopic bone was present along the superior edge of the femoral component (Fig 1). The left knee then was revised using the technique previously described. Dense scar was found covering the patella (Fig 2) and throughout the knee. The femoral component was revised to a smaller, slightly undersized posterior stabilized prosthesis; scar tissue was excised and the tibial tubercle was recessed to lengthen the extensor mechanism. Although Grade 1 heterotopic bone reformed after the revision surgery, the patient’s pain was relieved and she has 0° to 80° flexion.