Females show worse functional outcome and quality of life compared to males 2 years after meniscus surgery: Data analysis from the German Arthroscopy Registry
Abstract
Purpose
The purpose of this study was to investigate the impact of sex on knee function, activity and quality of life following meniscus surgery using data from the German Arthroscopy Registry.
Methods
This is a retrospective cohort study with data collected between 2017 and 2022. Patient-reported outcome measures (PROMs), namely Knee Injury and Osteoarthritis Outcome Score (KOOS), EuroQol Visual Analogue Scale (EQ Scale), and Marx Activity Rating Scale (MARS), were collected preoperatively and at 6, 12 and 24 months postoperatively. Data were analysed to examine differences between male and female patients regarding PROMs, pre-existing conditions, meniscus lesion types and surgical treatments.
Results
A total of 1106 female (36.6%) and 1945 male patients (63.7%) were included. Males were significantly younger than females and had a higher body mass index. Overall, there were four times more medial meniscus lesions (MMLs) (77.5%) than lateral meniscus lesions (LMLs) (27.9%). Degenerative LMLs were more frequent in females, while traumatic LMLs were more common in males. Frequencies of traumatic and degenerative MMLs were similar among males and females. Males had higher absolute KOOS irrespective of treatment or meniscus lesion type. Meniscus repair resulted in similar improvements in ΔKOOS for both sexes, while meniscus resection exhibited higher absolute KOOS for males at each time point. Males generally had higher EQ Scale and MARS than females.
Conclusion
Greater improvements in knee function, activity and quality of life were observed in males. While MMLs appear to be comparable among sexes, the nature of LML differed significantly. These results may help surgeons to refine patient selection for specific treatments to improve overall clinical outcomes.
Level of Evidence
Level III.
Abbreviations
-
- ACI
-
- autologous chondrocyte implantation
-
- ACL
-
- anterior cruciate ligament
-
- BMI
-
- body mass index
-
- DART
-
- German Arthroscopy Registry
-
- EQ Scale
-
- European Quality of Life Scale
-
- KOOS
-
- Knee Injury and Osteoarthritis Outcome Score
-
- LML
-
- lateral meniscus lesion
-
- MARS
-
- Marx Activity Rating Scale
-
- MML
-
- medial meniscus lesion
-
- MRI
-
- magnetic resonance imaging
-
- Pedi-IKDC
-
- Pediatric International Knee Documentation Committee (Score)
-
- PROM
-
- patient-reported outcome measure
-
- SD
-
- standard deviation
INTRODUCTION
Meniscus injuries significantly impact patients' quality of life and knee function due to the crucial role of menisci in knee stability, load distribution and shock absorption. These injuries can cause pain, restrict mobility and increase the risk of osteoarthritis. Surgical intervention is often required for acute traumatic or degenerative meniscus tears [1, 12].
Gender and sex aspects, as potential factor influencing postoperative outcomes, have been observed in previous studies for various orthopaedic conditions (e.g., anterior cruciate ligament [ACL] tears, cartilage lesions) [8, 19]. Conclusive data on the potential impact of sex or gender on the rate and severity of meniscus injuries, however, remain unclear [18, 19]. Besides these, other factors like lesion type (traumatic vs. degenerative) and surgical treatment method (meniscus suture vs. partial meniscectomy) may also affect postoperative outcomes [17, 26]. For surgical knee cartilage procedures, studies showed that females exhibit better relative postoperative Knee Injury and Osteoarthritis Outcome Scores (KOOSs) as compared to males; yet, males tend to achieve higher absolute KOOSs [9]. However, females exhibited a higher revision rate and greater subjective dissatisfaction than their male counterparts [8]. These factors warrant consideration to improve postoperative outcomes.
Therefore, the present study aimed to investigate the effect of sex on functional outcome, level of activity and quality of life, using data from the German Arthroscopy Registry (DART). It was hypothesised that functional outcome, activity level and quality of life would differ between males and females following meniscus surgery. Moreover, it was hypothesised that the choice of surgical treatment as well as meniscus lesion types would differ among sexes. Elucidating these relationships may optimise treatment strategies and ultimately improve the standard and quality of care for patients with meniscus injuries.
MATERIALS AND METHODS
Data source and collection
DART registry data from patients that underwent meniscus surgery between November 2017 and May 2022 were used for the present analysis. DART, a German multicenter registry established in November 2017, is a web-based platform that records patient characteristics after arthroscopic, open or nonoperative joint treatments in the knee, hip, ankle or shoulder, serving as both a quality assurance tool and a platform for healthcare research [11]. DART aims to monitor the safety and efficacy of arthroscopic joint surgery and nonsurgical joint-related therapies. Patient characteristics and patient-reported outcome measures (PROMs) are collected preoperatively (baseline) and at different follow-up time points postoperatively (6, 12 and 24 months) [3, 16, 23]. From November 2017 to May 2022, the registry included data from 6327 patients that underwent knee surgery. DART is conducted in accordance with the Declaration of Helsinki and registered at germanctr.de (DRKS00012994). Data registration and subsequent collection were approved by the coordinating institutional review board of the University of Freiburg (No. 624/19) as well as by the local ethics committees of every participating institution.
Patient selection
Eligible patients had to report their biological sex (male or female) and have had undergone surgical treatment for a meniscus lesion (meniscus sutures or partial meniscectomy). Additionally, patients qualified if they had registered KOOS, EuroQol Visual Analogue Scale (EQ Scale) or the Marx Activity Rating Scale (MARS). Meniscus lesions had to be identified as medial or lateral and traumatic or degenerative. Tibial meniscal refixation and reconstructive meniscal sutures were labelled as repairs, while minimal debridement of the meniscus, partial- and total resection were labelled as resection. Patients who reported both repair and resection were classified as repair. Patients were excluded if they did not report their biological sex or labelled it as diverse, if the meniscus lesion type (traumatic or degenerative) was not classified or if they did not report any PROMs at baseline and at least one follow-up visit.
Statistical analysis
Baseline patient characteristics were analysed by anthropometrics, including sex, preoperative conditions, epidemiology, aetiology and concomitant procedures. Z tests for proportions were used to compare fractional metrics statistically. Sex differences in patient characteristics were assessed using unpaired t tests. When examining sex differences in PROMs at baseline (preoperative) and follow-up (6, 12 and 24 months postoperative), unpaired t tests were used, considering all types of treatment and or resection and type of meniscus lesion (traumatic or degenerative). Mean differences in PROMs (ΔKOOS, ΔEQ Scale, ΔMARS) from preoperative to 6 months postoperative and subsequent follow-up periods (6–12 and 12–24 months) were tested for significant differences using a one-sample t test. Data were assessed for normal distribution, and appropriate parametric or nonparametric statistical tests were applied. A significance level of p ≤ 0.05 was established for the analyses. Statistical calculations were performed using Matlab (R2023a; MathWorks), and results were presented as mean ± standard deviation (SD).
RESULTS
Patient characteristics
Out of the entire patient population, 3051 patients met the eligibility criteria for the present study (Figure 1). Male (n = 1945) patients were significantly younger than female (n = 1106) patients (46.2 ± 13.8 vs. 48.6 ± 13.6 years; p < 0.01). BMI was higher in males than that in females (27.8 ± 6.0 vs. 27.2 ± 6.3; p = 0.02). No significant differences were observed regarding the time frame between onset of symptoms and surgery between male and female patients (21.4 ± 24.4 vs. 23.0 ± 24.7 weeks; n.s.).
Smoking habits were similar (12.4% vs. 10.8%; n.s.), but females reported higher preoperative physical activity (23.7% vs. 20.0%; n.s.) and had higher incidences of certain pre-existing conditions such as thyroid diseases (15.5% vs. 3.4%; p < 0.01) and depression (4.9% vs. 1.9%; p = 0.05). The five most frequently utilised nonoperative treatment options were pain medication, physiotherapy, technical aid (e.g., bandages and insoles), as well as rest. The use of pain medication and physiotherapy was reported more frequently in females than in males (p < 0.01).
Meniscus pathologies
Among the 3051 eligible patients, 25.1% underwent meniscus repair (63.4% males and 36.6% females), while 74.9% underwent meniscus resection (63.9% males and 36.1% females) (Figure 2a). Medial meniscus lesions (MML) were more common than lateral meniscus lesions (LML) across sexes, with degenerative causes predominating over traumatic ones. Males exhibited a higher incidence of traumatic LML, whereas females showed more degenerative LML. Complex tear patterns were most common in MML, with males more frequently having radial tear patterns in LML and females showing a prevalence of flap tear patterns (Table 1).
| Characteristics | Males | Females | P | ||
|---|---|---|---|---|---|
| n | % | n | % | ||
| Medial lesion | 1.507 | 77.5 | 828 | 74.9 | n.s. |
| Traumatic | 335 | 17.2 | 163 | 14.7 | n.s. |
| Degenerative | 1.172 | 60.3 | 665 | 60.1 | n.s. |
| Tear pattern | |||||
| Longitudinal | 87 | 4.5 | 46 | 4.2 | n.s. |
| Bucket handle | 68 | 3.5 | 16 | 1.5 | 0.05 |
| Radial | 103 | 5.3 | 74 | 6.7 | n.s. |
| Horizontal | 295 | 15.2 | 145 | 13.1 | n.s. |
| Complex | 555 | 28.5 | 304 | 27.5 | n.s. |
| Root | 23 | 1.2 | 55 | 5.0 | 0.03 |
| Flap | 311 | 16.0 | 137 | 12.4 | 0.04 |
| Ramp lesion | 14 | 0.7 | 6 | 0.5 | n.s. |
| Other | 39 | 2.0 | 25 | 2.3 | n.s. |
| Lateral lesion | 543 | 27.9 | 319 | 28.8 | n.s. |
| Traumatic | 258 | 13.3 | 102 | 9.2 | 0.05 |
| Degenerative | 285 | 14.7 | 217 | 19.6 | 0.04 |
| Tear pattern | |||||
| Longitudinal | 68 | 3.5 | 38 | 3.4 | n.s. |
| Bucket handle | 37 | 1.9 | 23 | 2.1 | n.s. |
| Radial | 112 | 5.8 | 42 | 3.8 | 0.05 |
| Horizontal | 51 | 2.6 | 34 | 3.1 | n.s. |
| Complex | 106 | 5.5 | 74 | 6.7 | n.s. |
| Root | 29 | 1.5 | 12 | 1.1 | n.s. |
| Flap | 78 | 4.0 | 44 | 4.0 | n.s. |
| Ramp lesion | 1 | 0.1 | 4 | 0.4 | n.s. |
| Other | 41 | 2.1 | 29 | 2.6 | n.s. |
- Note: Bold values are statistically significant.
The registry comprised isolated meniscus lesions and meniscus lesions with concomitant procedures. Major concomitant procedures that may influence rehabilitation protocols, like ACL reconstruction or regenerative cartilage procedures, were observed in a relatively low number of total cases and showed equal distribution among sexes. ACL reconstruction was the most common concomitant procedure for traumatic MMLs across sexes (7.9% vs. 7.3%; n.s.), followed by chondroplasty (1.6% vs. 2.1%; n.s.) and microfracture (0.7% vs. 0.9%; n.s.), with females slightly more likely to undergo chondroplasty together with degenerative MMLs (25.5% vs. 28.2%; p = 0.05). For traumatic LMLs, ACL reconstruction was again more common in males (8.6% vs. 5.7%; p < 0.01), followed by chondroplasty (0.5% vs. 0.2%; n.s.) and microfracture (0.4% vs. 0.3%; n.s.). Females underwent the procedure significantly more often than males (19.6% vs. 5.5%; p < 0.01).
Knee function
Irrespective of the type of treatment (repair or resection) or type of meniscus lesion (traumatic or degenerative), males demonstrated significantly higher absolute KOOS at baseline, 6, 12 and 24 months postoperatively compared to females (Table 2; Figure 2). To examine the potential impact of patient age on KOOS, patients were categorised into two age cohorts: those below 40 and those above 40 years of age. In the younger cohort, baseline KOOSs were higher for males compared to females (56.44 vs. 51.16; p < 0.01), a trend that persisted at 6 months (84.41 vs. 76.04; p < 0.01) and 12 months postoperative (87.11 vs. 85.00; p = 0.03). This pattern was also observed in the older cohort, where male participants demonstrated higher KOOSs than their female counterparts at baseline (57.47 vs. 49.61; p < 0.01), 6 months (80.01 vs. 72.27; p < 0.01) and 12 months postoperative (81.02 vs. 74.91; p < 0.01). Still, a limited sample size in the younger cohort (baseline: 312 vs. 149; 6 months: 105 vs. 42; 12 months: 85 vs. 34; 24 months: 53 vs. 18) precluded further statistical analysis at this time point with the available registry data.
| Baseline | 6 M | 12 M | 24 M | Baseline to 6 M | 6–12 M | 12–24 M | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Males | Females | p | Males | Females | p | Males | Females | p | Males | Females | p | Males | Females | p | Males | Females | p | Males | Females | p | |
| KOOS | 55.61 (15.74) | 50.17 (15.40) | <0.01 | 76.18 (15.42) | 70.71 (16.75) | <0.01 | 78.32 (15.18) | 74.32 (17.02) | <0.01 | 80.94 (13.94) | 76.74 (16.83) | 0.01 | 20.41* (15.41) | 21.07* (15.86) | n.s. | 2.01* (10.53) | 2.39* (10.08) | n.s. | 1.12 (9.07) | 1.61 (9.25) | n.s. |
| Repair | 52.54 (16.32) | 50.07 (16.63) | n.s. | 74.93 (13.84) | 70.11 (14.69) | n.s. | 78.24 (13.56) | 75.96 (13.99) | n.s. | 81.67 (9.79) | 75.19 (15.18) | n.s. | 21.49* (15.87) | 22.80* (17.05) | n.s. | 4.48* (9.53) | 4.57* (10.15) | n.s. | 1.01 (7.48) | −0.31 (7.97) | n.s. |
| Resection | 56.11 (15.60) | 50.20 (15.14) | <0.01 | 76.36 (15.63) | 70.85 (17.21) | <0.01 | 78.36 (15.40) | 73.93 (17.69) | <0.01 | 80.86 (14.31) | 77.13 (16.36) | 0.04 | 20.19* (15.33) | 20.64* (15.56) | n.s. | 1.51* (10.66) | 1.75* (10.00) | n.s. | 1.14 (9.32) | 2.22* (9.58) | n.s. |
| Traumatic lesions | 55.30 (16.29) | 48.75 (14.60) | <0.01 | 77.66 (13.55) | 67.68 (16.59) | <0.01 | 81.42 (11.61) | 72.83 (14.69) | <0.01 | 84.37 (10.70) | 77.56 (15.19) | 0.03 | 23.02* (15.48) | 20.17* (15.91) | n.s. | 4.59* (8.70) | 4.17* (9.84) | n.s. | 1.87* (6.02) | 10.03 (9.84) | n.s. |
| Lateral | 54.20 (19.16) | 48.14 (13.35) | 0.03 | 80.28 (12.14) | 74.42 (14.11) | 0.01 | 84.08 (12.88) | 75.48 (15.65) | <0.01 | 85.75 (12.95) | 80.53 (15.30) | n.s. | 25.23* (19.35) | 26.85* (16.53) | n.s. | 5.01* (9.73) | 4.05* (6.82) | n.s. | 2.89* (6.41) | 2.40* (7.26) | n.s. |
| Medial | 55.12 (18.03) | 46.39 (15.15) | <0.01 | 80.22 (15.49) | 72.25 (16.36) | <0.01 | 84.49 (13.49) | 80.80 (12.93) | n.s. | 87.74 (12.22) | 82.73 (13.33) | n.s. | 25.57* (16.40) | 25.57* (16.84) | n.s. | 3.97* (10.07) | 6.39* (12.65) | n.s. | 19.70* (15.34) | 19.70* (15.34) | n.s. |
| Degenerative lesions | 55.69 (15.60) | 50.51 (15.59) | <0.01 | 75.81 (15.85) | 71.52 (16.74) | <0.01 | 77.43 (15.96) | 74.72 (17.60) | n.s. | 79.99 (14.59) | 76.55 (16.36) | n.s. | 19.70* (15.34) | 21.31* (15.88) | n.s. | 1.21 (10.92) | 1.90* (10.12) | n.s. | 0.42 (6.10) | 3.19 (10.35) | n.s. |
| Lateral | 57.79 (18.19) | 50.44 (17.30) | <0.01 | 78.75 (16.92) | 72.94 (17.52) | 0.01 | 77.61 (18.16) | 73.75 (19.75) | n.s. | 78.52 (19.05) | 79.83 (18.70) | n.s. | 19.41* (18.24) | 21.57* (19.55) | n.s. | −1.99* (12.51) | −0.69 (9.44) | n.s. | 3.69* (11.65) | 3.22 (11.40) | n.s. |
| Medial | 57.76 (16.78) | 50.34 (16.75) | <0.01 | 79.81 (16.44) | 73.17 (18.42) | <0.01 | 81.26 (16.53) | 75.94 (19.39) | <0.01 | 82.56 (16.22) | 79.57 (17.26) | n.s. | 21.43* (16.46) | 22.73* (17.35) | n.s. | 1.34* (10.71) | 1.65* (10.91) | n.s. | 1.26 (10.86) | 0.68 (10.91) | n.s. |
| EQ Scale | 69.80 (20.06) | 67.21 (20.89) | 0.02 | 76.91 (21.28) | 76.84 (18.60) | n.s. | 78.88 (19.82) | 75.21 (23.22) | 0.04 | 79.86 (20.14) | 74.12 (24.71) | 0.02 | 6.54* (24.17) | 8.52* (21.73) | n.s. | 1.85 (20.98) | −3.09* (19.59) | <0.01 | −0.89 (24.27) | −0.06 (34.02) | n.s. |
| Repair | 65.26 (20.01) | 63.74 (20.48) | n.s. | 78.25 (16.76) | 78.77 (16.69) | n.s. | 81.43 (17.04) | 77.91 (22.19) | n.s. | 79.78 (21.02) | 78.61 (21.92) | n.s. | 11.64* (21.24) | 15.65* (22.84) | n.s. | 2.77* (15.36) | −0.72 (20.97) | n.s. | −3.55 (22.22) | 4.57 (29.09) | n.s. |
| Resection | 70.96 (19.80) | 67.54 (21.49) | <0.01 | 77.30 (21.04) | 75.18 (21.01) | <0.01 | 78.69 (20.11) | 73.68 (23.04) | <0.01 | 79.05 (19.93) | 75.67 (22.61) | n.s. | 6.55* (25.05) | 7.52* (25.98) | n.s. | 1.42 (20.99) | −2.74* (21.47) | <0.01 | −0.37* (23.16) | 0.37* (28.76) | n.s. |
| Traumatic lesions | 67.13 (20.48) | 64.27 (19.85) | n.s. | 79.00 (17.94) | 76.98 (19.56) | n.s. | 83.37 (16.88) | 80.57 (17.82) | n.s. | 80.00 (22.92) | 80.62 (18.40) | n.s. | 12.66* (22.98) | 13.34* (26.04) | n.s. | 5.31* (19.45) | 1.52 (18.79) | n.s. | −5.97 (28.10) | 3.83 (25.73) | n.s. |
| Lateral | 67.16 (20.15) | 65.27 (20.29) | n.s. | 81.78 (11.46) | 81.43 (17.37) | n.s. | 83.56 (16.50) | 82.69 (15.08) | n.s. | 80.67 (19.71) | 81.15 (19.21) | n.s. | 14.48* (20.56) | 16.37* (27.67) | n.s. | 3.51 (19.40) | 1.67 (9.82) | n.s. | −1.57 (32.08) | 1.09 (26.41) | n.s. |
| Medial | 66.00 (20.88) | 62.83 (19.29) | n.s. | 77.18 (20.30) | 76.41 (19.33) | n.s. | 83.20 (16.71) | 80.94 (18.22) | n.s. | 78.66 (25.67) | 80.19 (19.69) | n.s. | 12.27* (24.15) | 14.25* (24.06) | n.s. | 6.45* (18.93) | 1.14 (21.56) | n.s. | −9.74* (25.35) | 2.94 (26.35) | 0.03 |
| Degenerative lesions | 70.38 (19.78) | 67.27 (21.61) | <0.01 | 76.78 (20.95) | 75.38 (20.75) | n.s. | 77.63 (20.35) | 73.62 (23.52) | 0.01 | 78.40 (19.74) | 75.58 (23.14) | n.s. | 5.63* (24.33) | 8.13* (25.75) | n.s. | 0.77 (20.72) | −2.51* (21.19) | 0.04 | 0.10 (21.88) | 0.45 (29.06) | n.s. |
| Lateral | 69.32 (19.60) | 66.92 (22.29) | n.s. | 74.98 (21.62) | 75.98 (20.16) | n.s. | 72.12 (22.89) | 72.59 (25.78) | n.s. | 72.84 (22.68) | 72.46 (26.02) | n.s. | 5.74* (24.68) | 9.93* (30.22) | n.s. | −1.90 (23.46) | −5.05* (22.68) | n.s. | 3.36 (28.19) | 1.71 (37.14) | n.s. |
| Medial | 70.48 (19.96) | 67.27 (21.62) | 0.01 | 76.89 (21.34) | 75.40 (20.63) | n.s. | 78.19 (20.18) | 73.70 (22.79) | <0.01 | 78.48 (20.04) | 76.33 (21.73) | n.s. | 5.41* (24.55) | 7.78* (25.01) | n.s. | 1.40 (20.61) | −1.75 (20.33) | n.s. | −0.64 (21.74) | 0.32 (25.81) | n.s. |
| MARS | 2.02 (3.65) | 1.54 (3.09) | 0.02 | 2.33 (3.21) | 1.97 (3.37) | n.s. | 2.81 (3.64) | 1.93 (3.27) | <0.01 | 3.00 (3.73) | 2.33 (3.44) | n.s. | 0.47* (3.65) | 0.70* (4.03) | n.s. | 0.43* (3.30) | 0.03 (3.27) | n.s. | 0.20 (3.11) | 0.07 (3.10) | n.s. |
| Repair | 1.98 (3.90) | 1.71 (3.45) | n.s. | 2.94 (3.67) | 1.81 (2.91) | <0.01 | 3.47 (4.05) | 2.17 (3.31) | <0.01 | 3.61 (4.38) | 2.46 (3.80) | n.s. | 1.17* (4.12) | −0.03 (3.62) | 0.02 | 0.70* (3.49) | 0.41 (3.35) | n.s. | 0.65 (3.05) | 0.50 (3.07) | n.s. |
| Resection | 1.95 (3.57) | 1.51 (3.00) | 0.03 | 2.48 (3.36) | 1.95 (3.23) | 0.01 | 2.72 (3.63) | 1.98 (3.22) | <0.01 | 2.81 (3.64) | 1.93 (3.15) | <0.01 | 0.63* (3.90) | 0.62* (3.80) | n.s. | 0.32* (3.30) | 0.13* (2.78) | n.s. | 0.08* (3.10) | −0.01* (2.76) | n.s. |
| Traumatic lesions | 2.31 (4.03) | 2.09 (3.95) | n.s. | 3.49 (3.76) | 2.11 (3.46) | <0.01 | 4.35 (4.26) | 2.49 (3.89) | <0.01 | 3.37 (4.35) | 2.96 (4.07) | n.s. | 1.28* (4.47) | 0.08 (4.29) | 0.04 | 0.98* (3.76) | 0.60 (3.57) | n.s. | 0.65 (3.01) | 0.70 (3.53) | n.s. |
| Lateral | 2.08 (4.03) | 2.82 (4.71) | n.s. | 3.68 (3.82) | 2.86 (4.29) | n.s. | 4.34 (4.00) | 2.98 (4.41) | n.s. | 4.41 (4.21) | 2.96 (4.22) | n.s. | 1.48* (4.82) | 0.23 (5.36) | n.s. | 0.89 (3.68) | 0.70 (3.28) | n.s. | 0.82 (2.94) | 0.05 (2.98) | n.s. |
| Medial | 2.37 (3.99) | 1.95 (3.71) | n.s. | 3.31 (3.76) | 1.95 (3.20) | 0.01 | 4.31 (4.36) | 2.90 (4.16) | 0.04 | 4.30 (4.40) | 3.46 (4.53) | n.s. | 1.27* (4.16) | −0.31* (4.21) | 0.02 | 1.11* (3.96) | 1.00 (3.81) | n.s. | 0.59 (3.18) | 1.10 (3.62) | n.s. |
| Degenerative lesions | 1.76 (3.36) | 1.51 (2.94) | n.s. | 2.24 (3.18) | 1.93 (3.14) | n.s. | 2.39 (3.40) | 1.91 (3.06) | 0.04 | 2.47 (3.42) | 1.89 (3.11) | n.s. | 0.58* (3.52) | 0.59* (3.76) | n.s. | 0.20 (3.06) | 0.05 (2.77) | n.s. | −0.05 (3.05) | −0.01 (2.66) | n.s. |
| Lateral | 1.82 (3.61) | 1.50 (2.91) | n.s. | 2.25 (3.30) | 1.93 (3.10) | n.s. | 2.17 (3.39) | 2.17 (3.12) | n.s. | 2.07 (2.89) | 1.71 (2.90) | n.s. | 0.77 (3.50) | 0.38 (3.87) | n.s. | 0.01 (3.21) | 0.06 (2.96) | n.s. | 0.45 (2.99) | −0.20 (1.46) | n.s. |
| Medial | 1.73 (3.30) | 1.50 (2.98) | n.s. | 2.20 (3.18) | 2.00 (3.18) | n.s. | 2.41 (3.43) | 1.95 (3.12) | n.s. | 2.49 (3.45) | 1.84 (3.11) | 0.05 | 0.57* (3.50) | 0.70* (3.78) | n.s. | 0.21 (3.08) | 0.12 (2.68) | n.s. | −0.08 (3.12) | −0.05 (2.86) | n.s. |
- Note: Bold values are statistically significant.
- Abbreviations: EQ Scale, European Quality of Life Scale; KOOS, Knee Injury and Osteoarthritis Outcome Score; MARS, Marx Activity Rating Scale.
Males experienced significant improvements in ΔKOOS from baseline up to 24 months postoperative, whereas females saw improvements only up to 12 months, with no further gains beyond this point. Changes in ΔKOOS between males and females were similar and not statistically significant for any follow-up (Table 2).
Upon stratification by suture treatment, it was observed that males had higher KOOSs than females initially, but this difference evened out by 12 months. (Figure 2a). Both male and female patients exhibited significant improvements in ΔKOOS from baseline to 6 and 6–12 months postoperative, with no further gains from 12 to 24 months postoperative. No sex differences in ΔKOOS were observed at any follow-up (Table 2).
Upon stratification by meniscus resection, males exhibited significantly higher absolute KOOS than females at all periods of time (Figure 2a). Both sexes showed significant improvements in ΔKOOS across all periods. When comparing males and females, no sex differences in ΔKOOS were observed at any follow-up (Table 2).
Upon stratification by traumatic meniscus lesions, male patients displayed significantly higher absolute KOOS than females at all time points (Figure 2b). Improvements in ΔKOOS for males with traumatic meniscus lesions were significant up to 12 months postoperative, with no further improvement afterwards. Improvements in ΔKOOS for female patients were significant towards all follow-ups. Changes in ΔKOOS were similar for male and females at any follow-up (Table 2).
Upon stratification by degenerative meniscus lesions, male patients displayed significantly higher absolute KOOS up to 12 months postoperative, with no differences at 24 months postoperative (Figure 2b). Both genders showed significant ΔKOOS improvements up to 12 months; males continued to improve up to 24 months, while females did not. When comparing males and females, no sex differences in ΔKOOS were observed at any follow-up (Table 2).
Quality of life
Preoperatively and 12 months postoperative, males had better absolute EQ Scale than females for all patients with a meniscus lesion, regardless of suture or resection, traumatic or degenerative (Table 2; Figure 2). Males experienced a significantly improved ΔEQ Scale from baseline to 6 and 6–12 months postoperative but not from 12 to 24 months. Females improved up to 6 months and then saw a decrease from 6 to 12 months, with no changes thereafter. The improvement in ΔEQ Scale was significantly higher for males only from 6 to 12 months (Table 2).
Activity level
Compared to females, males had significantly higher absolute MARS at all periods of time. (Table 2; Figure 2). Males exhibited significant improvements in ΔMARS from before surgery up to 12 months postoperative, with no change after that. Females improved significantly only up to 6 months, with no further gains. Sex differences in ΔMARS were not observed for any follow-up (Table 2).
Follow-up rates
For male patients, KOOS follow-up data were available for 74% at 6 months postoperative, 62% at 12 months and 40% at 24 months. Conversely, among female patients, the available KOOS follow-up data were slightly higher, with 77% at six months, 66% at 12 months and 37% at 24 months postoperative. Compared to KOOS follow-up rates, EQ Scale follow-up rates tend to be lower for both males and females (6 months: 68% vs. 71%; 12 months: 56% vs. 61%; 24 months: 36% vs. 34%). In contrast, the highest follow-up rates were observed in both sexes for MARS (6 months: 77% vs. 83%; 12 months: 67% vs. 71%; 24 months: 41% vs. 40%).
DISCUSSION
The most important findings of the present study were that differences between male and female patients in terms of pre-existing conditions, meniscus lesion types, surgical treatments and related postoperative outcomes were apparent. Based on the results, the hypotheses that PROMs would differ between males and females and that the type of surgical treatment and meniscus lesion would result in different PROMs for both sexes were confirmed. In short, the DART registry data showed that males generally exhibited higher absolute KOOS, EQ Scale and MARS scores than females at baseline and all follow-up time points. Furthermore, males tended to show greater improvements in ΔPROMs than females. Moreover, the type of meniscus lesion (traumatic vs. degenerative) and treatment (repair vs. resection) impacted clinical outcomes differently for males vs. females. Regarding demographic data, the mean patient age in the presented cohorts is generally above 40 years. This is explained by the fact that arthroscopic surgery is the standard of care for meniscus pathologies in the examined healthcare system among all ages in the absence of osteoarthritis. Such demographic inclusivity ensures that the presented findings are broadly applicable and representative of a typical patient population in clinical practice. Presented age ranges are in line with comparable registry studies reporting ages of 40.2 ± 15.7 years for meniscus repairs and even 52.6 ± 13.9 years for meniscus resection [13].
The study suggests that higher rates of pre-existing conditions in females might explain their lower PROMs compared to males, who typically show greater postoperative improvements. These findings align with previous studies that have reported sex or gender differences in the prevalence of comorbidities and their impact on outcomes following orthopaedic surgery [4]. Differences in biomechanics, hormones and activity preferences between sexes may also affect meniscus lesion characteristics, underlining the importance of gender-specific approaches in treatment planning and outcome optimisation [2, 5].
The study indicates that gender-specific aetiology and risk factors, such as a higher prevalence of valgus deformities in women, contribute to the observed differences in meniscus lesion types: degenerative lesions are more common in females, and traumatic lesions are more frequent in males. Differences in cartilage and meniscus composition between genders may also play a role. These findings, aligned with existing literature, suggest that understanding these disparities is crucial for healthcare providers to make informed decisions in diagnosing and treating meniscus lesions, taking into account the unique risk profiles of each sex [22].
Chondroplasty was more frequently performed in females than in males as a concomitant procedure. This finding could be linked to the higher incidence of degenerative LMLs in females as well as a sexually divergent incidence of cartilage degeneration [8, 22]. Further research and multivariate analysis within the registry data are needed to explore the implications of these findings on the choice of concomitant procedures for each sex.
Irrespective of type of the treatment (repair or resection) or meniscus lesion (traumatic or degenerative), males consistently exhibited higher absolute KOOS values. The ΔKOOS, however, improved in both sexes improved until 12 months postoperatively, which suggests that meniscus surgery is generally effective in improving knee function. However, further research is required to determine whether the observed sex differences in KOOS have a meaningful impact on the long-term functional outcome. The finding that males had higher absolute KOOS irrespective of treatment type or meniscus lesion type is in line with previous research that has reported better PROMs in males following meniscus as well as other procedures [8, 15]. Moreover, it was observed that males and females improved ΔKOOS until 12 months postoperative, consistent with previous studies on meniscus surgery outcomes [10, 25].
The present study also revealed that the type of meniscus treatment (suture or resection) had different effects on the absolute KOOS for males and females. While repair resulted in similar improvements in ΔKOOS for both sexes, resection treatment led to higher absolute KOOS for males at each time point. This must be read with great caution, however, due to the limited follow-up of only 24 months so far. Mid- to long-term follow-ups of the present cohort are needed to answer any question about the superiority of either suture or resection regarding possible clinical outcomes.
Traumatic and degenerative meniscus lesions also exhibited different patterns of KOOS improvement between sexes. Males with traumatic meniscus lesions continued to show improvements in ΔKOOS after 12 months postoperative, whereas females did not. Conversely, females with degenerative meniscus lesions showed continued improvements in ΔKOOS beyond six months postoperative, while males did not. These findings highlight the importance of considering the type of meniscus lesion when evaluating treatment outcomes for male and female patients. Another explanation may be the partial inapplicability of clinical scores like KOOS for men and women. This remains an ongoing debate in the literature [14].
Males generally had higher EQ Scale and MARS than females. While both sexes improved their ΔEQ Scale and ΔMARS 6 months postoperative, males continued to show improvements in ΔMARS up to 12 months postoperative, while females did not. These findings suggest that there may be inherent differences in the postoperative recovery patterns between sexes, which warrants further investigation.
While the present study offers valuable insights into the impact of sex on PROMs following meniscus surgery, several limitations should be acknowledged. First, the present study reports short-term data which allowed for the detection of first tendencies in sex differences following meniscus surgery. However, it did not allow for a qualified judgement over treatment strategies (repair vs. resection) yet since it is known that resection may perform better in short term but fails to sustain good clinical outcomes at mid- to long-term follow-up when compared with meniscus repair [1]. Data quality issues, such as coding errors, misdiagnoses and missing information, may have influenced the present results. Nonetheless, registry data may still give valuable real-life data on treatment results, including safety issues and short- to long-term outcomes, while including patients not typically represented in clinical trials [21]. Furthermore, there need to be more patient follow-ups on PROMs as well as more adherence. Follow-up rates were lower than in typical observational studies but were similar to other registry studies that have been published earlier [11].
The rates of isolated meniscus surgeries were 25% for MMLs in males and 19% in females and less than 1% for LMLs in both biological sexes. Consequently, various concomitant procedures may have influenced the PROMs. Finally, detecting sex-specific differences in PROMs strongly relies on questionnaires being appropriate for their specific use. As an example, significant differences have already been reported in children, when using adult PROMs versus the Pediatric International Knee Documentation Committee score following knee ligament injuries [7]. Similar implications have been reported for gender or sex differences in foot and shoulder pathologies [6, 24]. Inherent gender and sex differences may lead to variations in symptom presentation, treatment response and overall quality of life assessments. For instance, women may experience distinct hormonal fluctuations and reproductive health issues that can impact their PROMs in areas or subsets such as pain, fatigue and emotional well-being [6]. Additionally, men and women may have different baseline resilience, affecting their perceptions of functionality, mobility as well as pain perception and mental health [20]. These specific disparities highlight the importance of accounting for biological sex as well as its delimitation to the more societal gender when interpreting PROMs, as it can guide personalised treatment approaches and optimise healthcare outcomes for both sexes. More investigations and subsequent validations are needed towards sex-specific scoring systems and PROMs to reflect these differences properly.
Registry research provides valuable real-world insights into treatment outcomes and safety profiles, complementing the controlled environments of clinical trials, which are more precise but less generalisable. While registries offer broad, diverse data that can uncover wide-ranging treatment effects and trends, they also face challenges like data quality and privacy concerns. Big data in healthcare enhances the potential for deep analysis but demands significant computational and privacy safeguards. Clinical trials and registry studies each have unique advantages, and their integration can enrich medical knowledge and improve evidence-based practice. Healthcare professionals are encouraged to utilise both approaches for optimal patient care.
Significant differences between male and female patients in terms of pre-existing conditions, types of meniscus lesions, surgical treatments and postoperative outcomes are presented in this study. It, therefore, highlights the need for further investigation into the long-term effects of different treatments and their inherent postoperative recovery between sexes and thus advocates for future sex-specific approaches in the treatment of common musculoskeletal pathologies.
CONCLUSION
The present study demonstrated significant sex differences in preoperative patient characteristics and functional outcome, level of activity and quality of life following meniscus surgery. While MMLs appear to be comparable among sexes, the nature of LMLs differed significantly. In females, more degenerative LMLs were observed, whereas traumatic LMLs were more common in male patients. Furthermore, greater improvements in knee function, activity and quality of life were observed in males. These results may help surgeons to refine patient selection for specific treatments to improve overall clinical outcomes.
AUTHOR CONTRIBUTIONS
Celine Mai aggregated and prepared the registry data, performed the statistical analyses, created the tables and figures, performed the literature research and drafted the manuscript. Patrick Mai participated in the statistical analysis and creation of tables and figures. Maximilian Hinz participated in the aggregation and preparation of the registry data. Philip P. Roessler conceived the study, devised the design, participated in the literature research and drafting of the manuscript. Rebecca Saenger and Thomas Tischer critically read and revised the manuscript. All authors read and approved the final manuscript.
ACKNOWLEDGEMENTS
The authors thank the German Arthroscopy Registry (DART) for providing data for the study. Open Access funding was enabled and organised by Projekt DEAL. The German Arthroscopy Registry (DART) is an initiative by the Society for Arthroscopy and Joint Surgery (AGA), German Professional Association for Arthroscopy (BVASK), Society for Orthopaedic Traumatologic Sports Medicine (GOTS) in cooperation with the German Knee Society (DKG), and German Association for Orthopaedics and Trauma (DGOU). Open Access funding enabled and organized by Projekt DEAL.
CONFLICT OF INTEREST STATEMENT
Three of the authors (Thomas Tischer, Maximilian Hinz and Philip P. Roessler) are members of the scientific advisory board of the German Arthroscopy Registry (DART). The remaining authors declare no conflict of interest.
ETHICS STATEMENT
The German Arthroscopy Registry (DART) is conducted in accordance with the Declaration of Helsinki and registered at germanctr.de (DRKS00012994). Data registration and subsequent collection were approved by the coordinating institutional review board of the University of Freiburg (No. 624/19) as well as by the local ethics committees of every participating institution. Informed consent was obtained from all individual participants included in the study.
