Early treatment of RA and AS can effectively prevent joint destruction and improve the quality of life by controlling symptoms and inflammation. The main antirheumatic drugs used are: ①Non-steroidal anti-inflammation drugs; ②Glucocorticoids, local injection to treat refractory peripheral arthritis; ③Rheumatology medication, the drugs recommended by the American Academy of Rheumatology classification standards mainly include sulfasalazine and methotrexate and leflunomide, etc.; ④Biological agents, TNF antagonists are the first choice, which can improve the pain and function of the axial joints; ⑤Thalidomide, special patients, when other related drugs have no effect, these drugs can significantly improve clinical symptoms7.
Due to severe pain, restricted mobility and deformities in patients with advanced RA and AS, medical treatment can no longer meet the needs of patients, then TKA is the best choice1. As patients with RA and AS have relatively young age, active lifestyles, and higher requirements for postoperative results, in addition to reasonable rehabilitation exercises, whether the continued use of drug therapy after surgery can improve knee joint function. To verify this idea, we conducted follow-up observations on these two types of patients.
Our series (44 stiff knees: 27 with sequential drug treatment versus 17 without sequential drug treatment knees) was the first series of TKAs in stiff patients with limited ROM of 50° or less to verify this question. Our data observed that stiff knee patients with sequential antirheumatic drug treatment after TKA had a better clinical and functional outcome at week 6 after TKA than patients without antirheumatic drug treatment, but a lower scores in functional part of KSS at month 6, year 1 and year 2. The clinical scores of KSS at other following-up time were not statistically significant (p＞0.05) .
We considered that under taking analgesia in both groups in week 6 after TKA, patients taking anti-rheumatic drugs at the same time had a greater degree pain relief and local inflammation control, thereby better improved their postoperative clinical and functional scores of KSS at week 6 after TKA. Then the two groups of patients stopped using conventional analgesics simultaneously, patients in group 1 continued anti-rheumatic drug treatment, and patients in group 2 stopped taking antirheumatic drugs due to economic problems or active exercise awareness. We believed that under economic pressure or active exercise awareness, their (in group 2) activity level would increase in order to recover quickly, which made them have a higher KSS functional scores at month 6, year 1 and year 2 after TKA. This situation was speculated to a certain extent that the amount of activity is related to the KSS after TKA.
There was not much published information regarding results of TKAs in knees with a preoperative arc of motion less than 50°. Aglietti and Buzzi (20 stiff knees, six ankylosed knees) reported ankylosed knees achieved less motion than stiff knees3. Montgomery et al reported no difference in the results after TKA when comparing ankylosed knees with knees of relatively normal motion2. Dr. Ashok Rajgopal (96 patients, 115 knees) reported the long-term functional outcome scores of stiff knees in extension and in flexion are similar8. However, no studies included stiff knee patients to accurately compare stiff knees with sequential antirheumatic drug treatment after TKA with those without to identify the functional improvement.
Postoperative arc of flexion ranging from 64°-103° had been reported in stiff and ankylosed knees in series ranging from 3 to 84 knees9. Our results were comparable to those of previous studies.
In our study the median postoperative arc of motion at different following time in two groups were not statistically significant (p＞0.05) (Table 4), but the median and mean ROM of patients who did not use antirheumatic drugs (group 2) were both higher than those who used antirheumatic drugs (group 1) at month 6, year1 and year 2. This may indicate that patients who did not take antirheumatic drugs sequentially had greater mobility of their knee joints because of active rehabilitation activities.
Postoperatively, VAS at different following time in two groups were not statistically significant (p＞0.05) (Table 4) . But the mean VAS in group 1 were higher than those in group 2 at month 6, year1 and year 2. This may indicate that patients with sequential use of antirheumatic drugs were more sensitive to pain, which limited their postoperative activity.
FJS at year 2 were 50 (range, 25-100) in group 1 and 75 (range, 25-75) in group 2 (Table 4) (p =0.335). This may indicate that patients with sequential antirheumatic drug treatment after TKA did not make sense to forget joint replacement.
In terms of higher satisfaction after TKA in patients with sequential drug treatment, we considered that patients who took antirheumatic drugs continually (at week 6, month 6, year 1 and year 2) after TKA would help relieve their general discomfort and control local inflammation (Table 5).
In addition, small bone sizes, severe osteopenia in a high proportion of patients with RA and AS, and severe soft tissue contractures made the operation technically demanding10. During exposure, stiff knees may need a rectus snip for exposure. Knees with osseous ankylosis in extension almost always need VY quadricepsplasty before the patella can be everted to minimize the risk of patellar tendon avulsion11. Aglietti and Buzzi recommended early quadricepsplasty to aid in exposure and patellar eversion without compromising the integrity of the patellar tendon3. We performed early quadricepsplasty in 4 knees with osseous ankylosis in extension. Twenty knees underwent plus osteotomy on the femoral side and three knees underwent plus osteotomy on the tibial side. One patient underwent quadriceps garter treatment. Three cases of knee joints underwent iliotibial band lysis. All patients underwent subperiosteal dissection.
A constrained total knee prosthesis has been recommended for converting a fused knee to a TKA to substitute for deficient or absent collateral ligaments12, in our experience, posterior-stabilized prostheses were also performed successfully in patients with stiff knees.
McAuley et al evaluated 27 TKAs in patients with a preoperative range of flexion less than 50°4. They reported an overall complication rate of 41% with a revision rate of 18.5%. Similar high complication and revision rates were reported by Naranja et al in patients who had TKAs for ankylosed knees13. The overall revision rate in our series (2.27%) was lower than rates in previous studies.
Our study has several limitations. The primary limitation is that the study lacked adequate power to compare the results of TKAs in patients with knees ankylosed in extension with the results in patients with knees ankylosed in flexion. The other limitation is that several prostheses were used during the study, and the comparison of results based on the implant used also would be prone to inadequate power. To sit in a chair without using one’s hands requires 93° knee flexion on average, and tying one’s shoes while seated requires 106° flexion on average, more cases are needed for subgroup analysis from the two angles8.
Our results were inferior to results of a standard primary TKA and had a lower KSS and FJS14. The surgery is technically demanding and should be performed only by a surgeon with considerable experience. Patients need to be counseled preoperatively regarding the possibility of a suboptimal outcome compared with that of a standard TKA performed in a mobile knee, the need for prolonged physiotherapy, more activity and higher tolerance, and the high complication rate.
In conclusion, for patients with stiff knees, the sequential antirheumatic drug treatment after TKA had no effect on postoperative KSS, but can improve the satisfaction. And according to the result of a higher postoperative functional values of KSS in patients without sequential drug treatment, we considered more postoperative activity or active awareness can improve postoperative function. We recommend patients with RA or AS undergo more activity in time after TKA.