Abstract
Background
Traditional teaching advocates for routine patella resurfacing (PR) during total knee arthroplasty (TKA) in patients with inflammatory arthritis. However, evidence on this topic remains limited in the Asian population. This study aims to evaluate the postoperative outcomes and complication of patella resurfacing (PR) during primary total knee arthroplasty (TKA) in Asian patients with inflammatory arthritis.
Methods
A retrospective analysis was conducted using registry data from our institution. Patients with inflammatory arthritis who underwent primary TKA from August 2017 to December 2021 were included in the study. Patients were divided into two groups - patella resurfaced (PR, n = 25) and non-resurfaced patella (PNR, n = 31) groups. Demographics, operative data, patient reported outcome measures, and complications were compared.
Results
Preoperative range of motion (ROM) (PR:95.3 ± 23.6° vs PNR:105 ± 19.5°, p = 0.106), Knee Society Scoring System Knee score (KS-KS) (PR:44.6 ± 17.4 vs PNR:49.3 ± 17.7, p = 0.331) and Knee Society Function Score (KS-FS) (PR:40.9 ± 27.3 vs PNR:47.7 ± 27.0, p = 0.325) and Oxford Knee Score (OKS) (PR:25.0 ± 7.8 vs PNR:23.3 ± 10.3, p = 0.525) were similar in both groups. Outcomes between PR and PNR groups at the one-year mark in terms of ROM (PR:112.7 ± 18.1 vs PNR:114.6 ± 16.5, p = 0.455), OKS (PR:41.5 ± 3.9 vs PNR:41 ± 4.7, p = 0.954), KS-KS (PR:84.5 ± 13.2 vs PNR:89.2 ± 9.3, p = 0.095) and KS-FS (PR:73.6 ± 18.3 vs PNR:78.7 ± 19.3, p = 0.173) were also similar. Intraoperative complication (PR:0/25 vs PNR: 3/31 (9.6 %), p = 0.245) and re-operation rates (PR: 1/25 (4 %) vs PNR: 1/31 (3.2 %), p = 0.877) were also similar in both groups.
Conclusion
This study conducted on a mixed Asian population with inflammatory arthritis demonstrated that the one-year postoperative ROM and functional outcomes, complication, and re-operation rates between PR and PNR groups were similar. Hence, routine patella resurfacing on all Asian patients with inflammatory arthritis undergoing TKA may not be necessary.
Keywords: Patella resurfacing, Primary total knee arthroplasty, Inflammatory arthritis, Mixed Asian population
1. Introduction
Patella resurfacing for TKA continues to be a controversial topic despite decades of discussion with newer and more updated evidence.1, 2, 3 There are three primary schools of thought: to always, never, or only selectively resurface the patella.4 Surgeons who routinely resurface the patella believe it significantly reduces the risk of postoperative anterior knee pain1,5 and rates of secondary resurfacing and reoperation.1,5,6 The group that never resurfaces the patella believes it avoids patella resurfacing-related complications,4 shorter operation time,7 more cost efficient7 with no statistical difference in functional outcomes.4 The group that selectively resurfaces the patella abides by a few relative indications, such as anterior knee pain, severe patellofemoral joint cartilage wear, and cases of inflammatory arthritis.4
In the Asian population, patients predominantly have smaller stature and thinner patellae.8,9 Current literature revealed paucity of information on patella resurfacing in Asian patients with inflammatory arthritis.10 Existing studies and knee registries on patella resurfacing are predominantly Caucasian based11 and mainly focus on osteoarthritis and rheumatoid arthritis, excluding other inflammatory arthritis conditions.10,12,13
This study aims to investigate the short-term postoperative clinical and functional outcomes, as well as the complication rates of patella resurfacing in a mixed Asian population with inflammatory arthritis who underwent primary TKA. The authors hypothesize that patella resurfacing need not be routine practice in all Asian patients with inflammatory arthritis undergoing primary TKA.
2. Methods and materials
A retrospective cohort study was conducted on a prospectively collected institutional knee arthroplasty registry database. Subjects with inflammatory arthritis who underwent primary TKA between August 2017 to December 2021 were included in this study. The exclusion criteria were patients without inflammatory arthritis, revision knee arthroplasty and unicompartmental knee replacement surgeries. Patients lost to follow-up one year post-operation were also excluded from this study. This study was performed using STROBE reporting guidelines.14
2.1. Surgical technique
In this series, TKAs are performed using conventional, navigated, and robotic techniques to restore the mechanical axis utilizing a mixture of gap balancing and measured resection, depending on the surgeons preference. During patella resurfacing, conventional patella cutting guides were used to obtain smooth and even cut surface and the desired thickness of residual patella. Cemented technique of the patella component was performed for all cases with resurfacing. In patients whom patellae are not resurfaced, patelloplasty and electrocautery circumpatellae denervation was performed. Modern “patella-friendly”, all polyethylene prostheses are utilized in all cases in this study.
In our institution, the decision to resurface the patella was based on the primary surgeons’ preference. Patellae that were too thin, too small, or too osteoporotic were contraindications to patella resurfacing.
Postoperatively, all patients were allowed to full weight bear on the operated limb, with no restriction in the knee range of movement. Early mobilization by physiotherapists and occupational therapists is initiated from the day of surgery.
2.2. Follow up and outcome measures
After TKA surgery, all patients are scheduled for review at two weeks, three months, six months, and one year post-operation. During their preoperative, three-month, and one-year post-operation reviews, all patients are assessed for their Knee Society Score (KSS), Oxford Knee Score (OKS), and range of movement (ROM). These outcome measures are recorded in the institution's knee registry database.
The OKS is a validated 12-item patient-reported measure questionnaire to determine post-TKA patients’ pain and function.15 The score consists of 12 questions, each with five possible responses that are scored from 0 to 4. The total score can range from zero to 48, with higher scores indicating better knee function and less pain. A study by Clement et al. demonstrated minimal clinically important difference (MCID) for the OKS was 5.0 points (95 % CI 4.4–5.5) for pain relief and 4.3 points (95 % CI 3.8–4.8) for function.16 This suggests that any statistical difference in these scores translates into meaningful clinical outcomes.
OKS questions 3, 5, 7 and 12 were selected for assessment of patellofemoral joint related outcomes.17
Q3. Have you had any trouble getting in and out of the car or using public transport because of your knee? (With or without a stick)
Q5. After a meal (sat at a table), how painful has it been for you to stand up from a chair because of your knee?
Q7. Could you kneel down and get up again afterwards?
Q12. Could you walk down a flight of stairs?
KSS score is subcategorized into “function” and “knee” components with three and seven items, respectively, comprising both patient-reported outcomes and clinical assessment of the operated knee. Each subcategory is scored out of 100, with higher scores indicating better clinical and functional status respectively. Lee et al. demonstrated that the MCID for the KSS Function Score is between 6.1 and 6.4, and for the KSS Knee Score to be between 5.3 and 5.9 after TKA.18
In this study, the ROM of the knee was measured using a goniometer by a trained nurse as an independent assessor. The goniometer is placed over the lateral epicondyle of the femur, with its proximal arm in line with the greater trochanter of the hip, while its distal arm is directed to the lateral malleolus of the ankle.
2.3. Statistical analysis
Sample size determination was based on the maximum number of available patients within the defined period. Descriptive statistics are reported as frequencies and percentages for categorical variables. A test of normality was performed on all continuous variables using Shapiro-Wilk tests. Student's t-test and Mann-Whitney U test were performed on continuous variables with or without normal distribution respectively. Fisher's exact test and Pearson's chi-square test were used for categorical variables. A p-value of <0.05 was considered to be statistically significant. Patients lost to follow-up at the 1-year post-operation review were excluded from the study.
Ethical statement
The study was approved by the institution's ethics committee (NHG DSRB Study Reference Number: 2020/00095, NHG DSRB Study Amendment ID: 2020/00095-AMD0003).
3. Results
A total of 2014 TKAs were performed from August 2017 to December 2021, of which 68 were cases of inflammatory arthritis. Twelve patients were removed from this study as they were lost to follow-up one year post-surgery. Fifty six patients were included in this study, of which 25 patients were in the patella resurfaced (PR) group while 31 were in the patella not resurfaced group (PNR). PR group consisted of 68 % RA cases while the PNR group had 58.1 % RA cases, p = 0.623. Other cases of inflammatory arthritis include systemic lupus erythematosus, psoriatic arthropathy, gout, pseudogout and juvenile idiopathic arthritis.
3.1. Baseline characteristics
Baseline demographics including age, gender, race, BMI, and American Society of Anaesthesiology (ASA) score were were comparable between the two groups (Table 1). Table 1 provides furrther details on the types of inflammatory arthritis present in each group.
Table 1.
Comparison of baseline demographics between patella resurfaced and patella not resurfaced groups.
| Patella Resurfaced |
Patella Not Resurfaced |
p-value | |
|---|---|---|---|
| N = 25 | N = 31 | ||
| Age | 63.1 ± 7.0 | 66.6 ± 6.1 | 0.054 |
| Gender | |||
| Male | 7 (28 %) | 8 (25.8 %) | 0.854 |
| Female | 18 (72 %) | 23 (74.2 %) | |
| Race | |||
| Chinese | 18 (72 %) | 21 (67.7 %) | 0.042 |
| Malay | 1 (4 %) | 7 (22.6 %) | |
| Indian | 6 (24 %) | 2 (6.5 %) | |
| BMI | 26.0 ± 6.9 | 25.3 ± 4.9 | 0.648 |
| ASA | |||
| 1 | 0 (0 %) | 1 (3.23 %) | 0.625 |
| 2 | 12 (48 %) | 13 (41.9 %) | |
| 3 | 13 (52 %) | 17 (54.8 %) | |
| Type of Inflammatory Arthritis | |||
| Rheumatoid Arthritis (RA) | 17 (68 %) | 18 (58.1 %) | 0.623 |
| Systemic Lupus Erythematosus (SLE) | 2 (8 %) | 2 (6.5 %) | |
| Psoriatic Arthropathy | 2 (8 %) | 1 (3.2 %) | |
| Inflammatory Spondyloarthropathy | 1 (4 %) | 1 (3.2 %) | |
| Seronegative Inflammatory Arthritis | 1 (4 %) | 1 (3.2 %) | |
| RA with SLE Overlap | 0 | 1 (3.2 %) | |
| RA with Sjoren's Syndrome Overlap | 0 | 3 (9.7 %) | |
| Polyarticular Juvenile Inflammatory Arthritis | 0 | 2 (6.5 %) | |
| Gout | 2 (8 %) | 1 (3.2 %) | |
| Pseudogout | 0 | 1 (3.2 %) | |
3.1.1. Preoperative treatment of inflammatory arthritis
Table 2 presents a comparison of the number of disease modifying anti-rheumatic drugs (DMARDs), biologic agents and glucocorticoid patients in each group were taking prior to surgery. There were higher percentage of patients in the PNR group were on three DMARDs preoperatively (12.9 % vs 0 %), but this difference did not reach statistical significance.
Table 2.
Preoperative treatment for inflammatory arthritis.
| Patella Resurfaced |
Patella Not Resurfaced |
P-value | |
|---|---|---|---|
| N = 25 | N = 31 | ||
| Number of Conventional DMARD Agents | |||
| 0 | 4 (16.0 %) | 4 (12.9 %) | 0.208 |
| 1 | 15 (60.0 %) | 13 (41.9 %) | |
| 2 | 6 (24.0 %) | 10 (32.3 %) | |
| 3 | 0 | 4 (12.9 %) | |
| Glucocorticoids | 19 (76.0 %) | 23 (74.2 %) | 0.877 |
| Biologics | 3 (12.0 %) | 2 (6.5 %) | 0.469 |
3.1.2. Intraoperative factors
A comparison of intraoperative factors between the two patient groups revealed that the duration of surgery and method of knee replacement (conventional, navigated, or robotic techniques) were statistically similar (Table 3).
Table 3.
Comparison of intraoperative factors and perioperative outcomes between PR and PNR groups.
| Patella Resurfaced |
Patella Not Resurfaced |
P-value | |
|---|---|---|---|
| N = 25 | N = 31 | ||
| Duration of Surgery (mins) | 115.9 ± 31.5 | 122.8 ± 50.4 | 0.711 |
| Technology Used | |||
| Conventional | 5 (20 %) | 2 (6.5 %) | 0.202 |
| Navigated | 16 (64 %) | 26 (83.9 %) | |
| Robotic | 4 (16 %) | 3 (9.7 %) | |
| Intraoperative Complications | |||
| No complications | 25 (100 %) | 28 (90.3 %) | 0.245 |
| Complications | 0 (0 %) | 3 (9.6 %) | |
| Reoperation | |||
| No reoperation | 24 (96 %) | 30 (96.8 %) | 0.877 |
| Reoperation | 1 (4 %) | 1 (3.2 %) | |
| OKS | |||
| Pre-operation | 25.0 ± 7.8 | 23.3 ± 10.3 | 0.525 |
| 3 months post-operation | 37.7 ± 6.1 | 36.6 ± 7.5 | 0.766 |
| 1 year post-operation | 41.5 ± 3.9 | 41 ± 4.7 | 0.954 |
| KSS (Knee) | |||
| Pre-operation | 44.6 ± 17.4 | 49.3 ± 17.7 | 0.331 |
| 3 months post-operation | 83.8 ± 10.2 | 83.6 ± 13.1 | 0.760 |
| 1 year post-operation | 84.5 ± 13.2 | 89.2 ± 9.3 | 0.095 |
| KSS (Function) | |||
| Pre-operation | 40.9 ± 27.3 | 47.7 ± 27.0 | 0.325 |
| 3 months post-operation | 62.7 ± 16.3 | 62.7 ± 28.2 | 0.572 |
| 1 year post-operation | 73.6 ± 18.3 | 78.7 ± 19.3 | 0.173 |
| ROM(°) | |||
| Pre-operation | 95.3 ± 23.6 | 105 ± 19.5 | 0.106 |
| 3 months post-operation | 108.2 ± 15.4 | 110.36 ± 13.4 | 0.561 |
| 1 year post-operation | 112.7 ± 18.1 | 114.57 ± 16.5 | 0.455 |
3.2. Clinical and functional outcomes and scores
3.2.1. Range of movement
From Table 3, the range of movement (ROM) in the PR group was 95.3° ± 23.6°, 108.2° ± 15.4° and 112.7° ± 18.1° at the preoperative, three months, and one year post-operation mark respectively, while the ROM in the PNR group was 105° ± 19.5°, 110.4° ± 13.4° and 114.6° ± 16.5° at a similar time frame. The results did not reach statistical significance at each respective time frame, with p-values of 0.106, 0.561, and 0.455 respectively. Comparison of ROM at one year post-operation to pre-operation showed statistically significant improvement (PR = 17.4° ± 22.5°, p < 0.001, PNR = 11.1° ± 17.9°, p < 0.001) (Table 4).
Table 4.
Comparison of one year post-operative versus pre-operative outcomes in PR and PNR groups.
| Patella Resurfaced |
Patella Not Resurfaced |
|||
|---|---|---|---|---|
| Improvement in Outcomes | P-value | Improvement in Outcomes | P-value | |
| OKS | 16.6 ± 9.6 | <0.001 | 17.7 ± 10.3 | <0.001 |
| KSS (Knee) | 39.9 ± 20.3 | <0.001 | 40.0 ± 20.3 | <0.001 |
| KSS (Function) | 31.9 ± 33.1 | <0.001 | 30.0 ± 27.1 | <0.001 |
| ROM (°) | 17.4 ± 22.5 | <0.001 | 11.1 ± 17.9 | <0.001 |
3.2.2. Oxford Knee Score
Similarly, from Table 3, a comparison of OKS between the two groups yielded similar results. The preoperative, three months, and one year post-operative OKS was 25.0 ± 7.8 vs 23.3 ± 10.3 p = 0.525, 37.7 ± 6.1 vs 36.6 ± 7.5 p = 0.766 and 41.5 ± 3.9 vs 41 ± 4.7 p = 0.954 in the PR and PNR groups respectively. The difference in OKS scores between the two groups at 3-months and 12-months postoperation were less than 5, suggesting that there is also no clinically significant difference in OKS outcomes. From Table 4, one-year post-operation versus pre-operation OKS scores showed statistically significant improvements (PR = 16.6 ± 9.6, p < 0.001 and PNR = 17.7 ± 10.3, p < 0.001).
3.2.3. Knee Society Score
KSS knee and function scores observed no statistical difference in results between the two groups at the three different time periods (Table 3). Comparison KSS knee score between PR and PNR groups showed the following results: 44.6 ± 17.4 vs 49.3 ± 17.7 p = 0.331, 83.8 ± 10.2 vs 83.6 ± 13.1 p = 0.760 and 84.5 ± 13.2 vs 89.2 ± 9.3 p = 0.095 at the three respective time period. KSS function scores for the three different time periods were 40.9 ± 27.3 vs 47.7 ± 27.0 p = 0.325, 62.7 ± 16.3 vs 62.7 ± 28.2 p = 0.572 and 73.6 ± 18.3 vs 78.7 ± 19.3 p = 0.173 in the PR and PNR group respectively.
However, a comparison between one-year post-operative to pre-operation KSS knee (PR = 39.9 ± 20.3, p < 0.001 and PNR = 40.0 ± 20.3, p < 0.001) and function scores (PR = 31.9 ± 33.1, p < 0.001 and PNR = 30.0 ± 27.1, p < 0.001) yielded statistically significant improvement in both groups (Table 4).
3.2.4. Patella-related outcome measures
A comparison of patella-related outcomes in terms of OKS questions 3, 5, 7 and 12, as demonstrated in Table 5, showed similar results across all fields at preoperative, 3-months and 12-months postoperative time points. However, the results also revealed that a higher number of patients were able to kneel down and get up, and climb stairs at 3 months postoperatively compared to 12 months postoperatively. Furthermore, PNR group had higher percentage of patients who could kneel and climb stairs easily or with only slight difficulty at the 3 months postoperative mark compared to PR group (OKS Q7: ability to kneel down and get up—PR group: 4.2 % vs. PNR group: 20 %; OKS Q12: ability to climb stairs—PR group: 0 %, PNR group: 10 %). However, this result did not reach statistical significance.
Table 5.
Comparison of patella-related outcomes between PR and PNR groups.
| Preoperative |
P-value | 3-months post-operation |
p-value | 12-months post-operation |
p-value | ||||
|---|---|---|---|---|---|---|---|---|---|
| Patella Resurfaced | Patella Not Resurfaced | Patella Resurfaced | Patella Not Resurfaced | Patella Resurfaced | Patella Not Resurfaced | ||||
| OKS Q3 | |||||||||
| No trouble | 0 | 0 | 0.320 | 0 | 0 | 0.193 | 0 | 0 | 0.510 |
| Very little trouble | 7 (29.2 %) | 5 (17.2 %) | 0 | 0 | 1 (5.0 %) | 0 | |||
| Moderate trouble | 5 (20.8 %) | 13 (44.8 %) | 3 (12.5 %) | 1 (3.3 %) | 0 | 1 (3.8 %) | |||
| Extreme difficulty | 9 (37.5 %) | 8 (27.6 %) | 5 (20.8 %) | 12 (40.0 %) | 5 (25.0 %) | 5 (19.2 %) | |||
| Impossible to do | 3 (12.5 %) | 3 (10.3 %) | 16 (66.7 %) | 17 (56.7 %) | 14 (70.0 %) | 20 (76.9 %) | |||
| OKS Q5 | |||||||||
| Not at all painful Slightly | 8 (33.3 %) | 9 (31.0 %) | 0.899 | 3 (12.5 %) | 3 (10.0 %) | 0.782 | 0 | 1 (3.8 %) | 0.705 |
| painful Moderately | 5 (20.8 %) | 7 (24.1 %) | 1 (4.2 %) | 2 (6.7 %) | 2 (10.0 %) | 2 (7.7 %) | |||
| painful | 4 (16.7 %) | 3 (10.3 %) | 2 (8.3 %) | 1 (3.3 %) | 1 (5.0 %) | 0 | |||
| Very painful | 4 (16.7 %) | 4 (13.8 %) | 3 (12.5 %) | 7 (23.3 %) | 2 (10.0 %) | 3 (11.5 %) | |||
| Unbearable | 3 (12.5 %) | 6 (20.7 %) | 15 (62.5 %) | 17 (56.7 %) | 15 (75.0 %) | 20 (76.9 %) | |||
| OKS Q7 | |||||||||
| Yes, easily | 1 (4.2 %) | 3 (10.3 %) | 0.603 | 1 (4.2 %) | 4 (13.3 %) | 0.383 | 1 (5.0 %) | 0 | 0.496 |
| With little difficulty | 3 (12.5 %) | 4 (13.8 %) | 0 | 2 (6.7 %) | 0 | 0 | |||
| With moderate difficulty | 7 (29.2 %) | 12 (41.4 %) | 4 (16.7 %) | 2 (6.7 %) | 1 (5.0 %) | 3 (12.0 %) | |||
| With extreme difficulty | 9 (37.5 %) | 8 (27.6 %) | 6 (25.0 %) | 8 (26.7 %) | 3 (15.0 %) | 2 (8.0 %) | |||
| No, impossible | 4 (16.7 %) | 2 (6.9 %) | 13 (54.2 %) | 14 (46.7 %) | 15 (75.0 %) | 20 (80.0 %) | |||
| OKS Q12 | |||||||||
| Yes, easily | 4 (16.7 %) | 3 (10.3 %) | 0.700 | 0 | 2 (6.7 %) | 0.337 | 0 | 1 (3.8 %) | 0.375 |
| With little difficulty | 2 (8.3 %) | 6 (20.7 %) | 0 | 1 (3.3 %) | 0 | 0 | |||
| With moderate difficulty | 5 (20.8 %) | 7 (24.1 %) | 2 (8.3 %) | 1 (3.3 %) | 0 | 0 | |||
| With extreme difficulty | 4 (16.7 %) | 5 (17.2 %) | 1 (4.2 %) | 4 (13.3 %) | 0 | 0 | |||
| No, impossible | 9 (37.5 %) | 8 (27.6 %) | 21 (87.5 %) | 22 (73.3 %) | 20 (100 %) | 25 (96.2 %) | |||
3.3. Intraoperative complications
Three cases of intraoperative complications were identified in the PNR group and none in the PR group (p = 0.245). Out of the three cases, there were two cases of posterior medial condyle fracture and one case of inadvertent rent in lateral patella retinaculum during lateral patella facetectomy.
3.4. Reoperation
There were two cases of reoperation within the one year follow-up period with one case in each group (p = 0.877). The patient in the patella resurfaced group developed foot drop postoperatively secondary to common peroneal nerve palsy. The patient subsequently underwent left common peroneal nerve exploration, neurolysis, neuroma excision, and nerve grafting using allograft and tibialis posterior tendon transfer to extensor digitorium and extensor hallucis five months after primary TKA. The patient in the PNR group had atraumatic periprosthetic fractures of her left femur two months and nine months after index surgery, likely secondary to severe osteoporosis. The patient underwent distal femur plating and quadriceps tendon repair and subsequently underwent removal of previous screws and intramedullary nailing of the left hip for subtrochanteric fracture respectively.
4. Discussion
The practice of patella resurfacing after primary TKA varies widely worldwide. It remains a common practice in the United States, averaging around 82 % of all cases from 2004 to 2014.19 While patella resurfacing has been on the rise in countries such as England and Australia between the same period, it has become less popular in Sweden and Norway,19 and adoption remains low in Asia.4
4.1. Anterior knee pain
Patella resurfacing has traditionally been considered necessary in cases of inflammatory arthritis to reduce the risk of revision surgery.20, 21, 22 However, this practice may be of little benefit, as the incidence of postoperative anterior knee pain is already low. For instance, a study by Fern et al., in 1992 reported a 26.9 % incidence anterior knee pain in rheumatoid arthritis patients treated with Mark I Insall-Burstein Total Condylar knee replacement without patella resurfacing.23 In contrast, more recent studies using modern TKA prostheses reported lower rates of anterior knee pain in RA patients without patella resurfacing, ranging from 7 % to 12.7 %.10,24 Furthermore, both Chareancholvanich et al. and Pehlivanoglu et al. observed similar incidence of anterior knee pain between osteoarthritis and rheumatoid arthritis patients without patella resurfacing.10,24 A study by Metsna et al. even demonstrated that RA patients who underwent total knee replacement without patellar resurfacing experienced lower rates of postoperative anterior knee pain compared to their osteoarthritis counterparts (15.1 % vs. 20.5 %, respectively).25 The findings from this study further supports this notion, as patella-related symptoms are similar in both groups 1-year postoperation. Therefore, the rationale for performing patellar resurfacing to reduce postoperative anterior knee pain in patients with inflammatory arthritis may be less compelling in current clinical context.
4.2. Modern patella-friendly implants
Our results showed that there is no difference in clinical and functional outcome measures. This can be explained by modern knee arthroplasty design and modern methods of disease control. Successful functional and clinical postoperative outcomes of patella resurfacing are highly dependent on the appropriateness of the patella implant's shape, size, and site. Modern knee arthroplasty implant designs place more emphasis on improving patellofemoral articulation. This is achieved by making adjustments to ensure that the patella implant conforms to the prosthetic trochlear groove and matches the radius of that groove more effectively.21 In a meta-analysis performed by Pavlou et al., the authors demonstrated that majority of the studies (4 out of 5) indicated enhanced functional outcomes when utilizing patella-friendly designs, even without patella resurfacing.21 In terms of clinical outcomes, a meta-analysis by Simpson et al. found no statistically significant difference in anterior knee pain or reoperation rates between patellar resurfaced and non-resurfaced groups when "patella-friendly" implants were used.26 This result is consistent with findings reported in other studies.3,27
4.3. Resurfacing-related complications
Patella resurfacing is not without complications. Pagnano and Trousdale reported that more than 50 % of patients with asymmetric bone cut (defined as greater than 2 mm difference in medial and lateral remnant bone thickness) experienced patella complications requiring revision surgery.28 Our study did not observe any patella resurfacing-related complications. However, Feng et al. reported 2.9-fold higher-increase in patella-related complications in RA patients compared to OA patients.12 Despite improvements in TKA prostheses in recent years with more patella-friendly designs, these implants are designed based on the anthropometry of the Western population and are of suboptimal fit for Asian patellae. Shaifuzain et al. performed a cross-sectional study on a cohort of Asian females to compare intraoperative patella dimensions with commonly used prosthetic component systems. The authors showed that 57.6 % of the patellae did not fit even the smallest implants,8 while a corresponding American study showed that only 25 % of their female patients were unable to accommodate their smallest implants.29 Kim et al. demonstrated thinner mean central ridge thickness in Koreans compared to the Western patient population.9 Additionally, gender differences are also seen, with significantly wider and thicker patella in males compared to females.30,31 Clarke et al. reported that female knees were eight times more likely to have a post-resection residual patellar thickness of 13 mm or less compared to males.29 Age also has a significant positive association with patella bone thickness and volume.32 In this study on inflammatory arthritis, all patients are Asians and predominantly female. The demographic profile of these patients predisposes them to have smaller and thinner patellae, increasing the theoretical risk of patella fractures during or after patella resurfacing.33 These did not happen in our series. The likely cause is the selective approach of the surgeons deciding not to proceed with the patella resurfacing if there was insufficient patella thickness or poor bone quality.
4.4. Early detection and treatment of inflammatory arthritis
Early detection and timely initiation of medical treatment remain the cornerstones in the management of inflammatory arthritis. Early initiation of disease-modifying antirheumatic drugs (DMARDs) has been shown to increase the likelihood of disease remission and slow down joint destruction.34 The introduction of tumour necrosis factor-alpha inhibitors in the late 1990s marked the beginning of the era of biologic DMARDs. Today, both biologic DMARDs and synthetic DMARDs are more widely available and have significantly improved the management of inflammatory arthritis by halting joint destruction.35 This advancement may contribute to greater longevity of the patellofemoral joint in patients with inflammatory arthritis.
Advancement in pharmacotherapy in management of inflammatory arthritis has also led to changes in the pattern of joint disease. Fujimura et al. observed that knee radiographs of RA undergoing TKA between 2013 and 2017 showed significantly higher rates of osteophytes and medial joint space narrowing compared to radiographs from earlier years (1997–2003).36 Similarly, Takeda et al. reported a decrease in typical radiographic features of RA and relative increase in OA-like features over a 16-year study period from 2006 to 2021.37 Our authors speculate that this factor may account for the comparable postoperative clinical and functional outcomes between the two groups observed in this study.
Lastly, a study by Goodman et al. demonstrated that RA patients with higher BMI and preoperative disease activities are at higher risks of experiencing worse postoperative pain and function one year after surgery.38 Hence, in this unique group of patients with inflammatory arthritis, future efforts should focus on optimising treatment to reduce disease activity preoperatively in order to improve long term postoperative outcomes.
4.5. Strengths and limitations
4.5.1. Strengths
Most studies in current literature focus on rheumatoid arthritis without including other forms of inflammatory arthritis.10,12,13 To our best knowledge, this is the first Asian study that evaluates patella resurfacing in all inflammatory arthritis. As a result, the findings from this study can be applied to a broader spectrum of patients with inflammatory arthritis. Future studies might consider adopting similar methodologies to evaluate surgical outcomes using modern implants in inflammatory arthritis affecting other joints, such as the hip, as the literature in these areas remains limited.39
4.5.2. Limitations
This study is not without its limitations. Despite utilizing our institution's registry data which and including all cases of inflammatory arthritis spanning across a reasonable four years, the sample size of this study remains to be small. This limitation may be attributed to the low incidence of TKA performed for these specific indications. Additionally, this study reported outcomes up to 1 year post surgery and lacked long-term outcome data. Boyd et al. observed that patella-related complications following patella resurfacing typically occur on an average of four years after surgery40; however, our study only includes data up to one year follow up. Hence, studies with longer follow-up periods may reveal potential differences in outcomes.
Lastly, this study did not account for the severity of disease, which can be a confounding factor in determining final postoperative outcomes. Future studies should consider incorporating disease severity markers such as Routine Assessment of Patient Index Data (RAPID3), RA Disease Activity Index (RADAI), Clinical Disease Activity Index (CDAI), MD Health Assessment Questionnaire (MDHAQ) and Disease Activity Scale (DAS28-ESR)38 to enable for a more detailed analysis comparing outcomes in patient with varying degree of disease severity.
5. Conclusion
This study conducted on a cohort of Asian patients diagnosed with inflammatory arthritis showed similar short and mid-term clinical and functional outcomes between PR and PNR groups. Further studies on patella resurfacing in inflammatory arthritis with a larger patient cohort, longer-term follow-up and higher level of evidence are essential to determine if routine patella resurfacing in inflammatory arthritis patients remains relevant today.
CRediT authorship contribution statement
Sherlyn Yen Yu Tham: Conceptualization, Methodology, Formal analysis, Investigation, Data curation, Writing – original draft, Writing – review & editing, Project administration. Wu Chean Lee: Conceptualization, Methodology, Formal analysis, Investigation, Writing – original draft, Writing – review & editing, Supervision. Zavier Yongxuan Lim: Investigation, Data curation. Remesh Kunnasegaran: Conceptualization, Methodology, Resources, Writing – review & editing, Supervision.
Funding/ Grants
No funding ,financial support or grants was received in this study.
Declaration of competing interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgments
Not applicable.
Contributor Information
Sherlyn Yen Yu Tham, Email: styymed@gmail.com.
Wu Chean Lee, Email: leewuchean@yahoo.com.
Zavier Yongxuan Lim, Email: zavi0002@e.ntu.edu.sg.
Remesh Kunnasegaran, Email: remesh.ortho@gmail.com.
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