Table 1

Musculoskeletal health conditions in former professional football players: data extraction from included studies

Article details (Author(s), year of publication, reference number, country of origin)	Study demographics	Study design and purpose	Health condition(s)	Assessment method(s)	Outcome
Arliani et al, 20145 (Brazil)	N=27 G=male A=45.67 (SD 5.91) C=14.89 years R=not provided	Cross-sectional study To compare the prevalence of osteoarthritis among a group of soccer players and non-professional athletes.	Knee OA	Quantification of pain through VAS, knee radiographs KOOS subjective questionnaire, SF-36, knee MRI	66.6% knee OA in dominant knee (controls: 46.7%) 66.6% knee OA in non-dominant knee (controls: 43.3%)
Armenis et al, 201144 (Greece)	N=150 G=male A=49.8 (SD 7.4) C=8–10 years R=not provided	Cross-sectional study To compare OA ankle findings in retired Greek professional footballers with those in the general population.	Foot and ankle OA	Questionnaire, clinical examinations, radiographs	4.1% clinical OA (controls: 3.56%) 8.8% radiographic OA (controls: 3.7%)
Chantraine, 198531 (Switzerland)	N=81 G=male A=40–74 C=6–15 years R=not provided	Cross-sectional study To examine the presence of knee OA in a group of retired former footballers and to investigate a relationship between limb axis, previous meniscectomy and the presence of OA.	Knee OA	Clinical examination, radiographs	20% clinical signs of knee OA 56% radiographic signs of knee OA 2% clinical signs, but no radiographic evidence of knee OA 17% clinical and radiographic evidence of knee OA
Drawer and Fuller, 20014 (UK)	N=185 G=male A=47.6 (SD 13.2) C=not provided R=not provided	Cross-sectional study To quantify the prevalence of osteoarthritis and the severity of pain in the lower limb joints of players retired from English professional soccer.	OA, hip OA, knee OA, ankle OA	Questionnaire	32% medically diagnosed with OA in at least one of the lower limb joints. 1.7% diagnosed with hip OA of the right hip 4.0% diagnosed with hip OA of the left hip 19.0% diagnosed with knee OA of the right knee 21.3% diagnosed with knee OA of the left knee 5.7% diagnosed with ankle OA of the right ankle 6.3% diagnosed with ankle OA of the left ankle 80% at least minor joint pain in at least one lower extremity joint during one or more daily activities 37% knee pain
Elleuch et al, 200832 (France)	N=50 G=male A=49.2 (SD 3.8) C=10.7 (SD 4.6) R =≥20	Case-control study To study the prevalence of knee osteoarthritis in a group of former professional footballers with comparison to a control group.	Knee OA, knee pain, knee disability	Questionnaire, knee examination, functional assessment using Arabic Lequesne index, knee radiographs, KL radiological classification	80% radiographic OA (controls: 68%) 12% knee pain (controls 34%) 12% knee disability (controls: 46%)
Fernandes et al, 20183 (UK)	N=1207 G=male A=59 (SD 11.7) C=not provided R=not provided	Case-control study To determine the prevalence of knee pain, RKOA, TKR and associated risk factors in male ex-professional footballers compared with men in the general population (comparison group).	Knee pain, knee OA, total knee replacement	Questionnaire, knee radiographs	52.2% knee pain (controls: 26.9%) 28.3% diagnosed with knee OA by a physician (controls: 12.2%) 64% signs of knee OA in radiographs (controls: 35.2%) 11.1% total knee replacement (controls: 3.8%)
Gouttebarge et al, 201818 (The Netherlands—Global)	N=396 G=male A=36 (SD 6) C=11 (SD 5) R=5 (SD 4)	Case-control study To investigate whether retired professional footballers with lower extremity OA have a lower health-related quality of life than those without OA or current professional footballers.	OA	Questionnaire	33% OA (mostly knee OA)
Iosifidis et al, 201533 (Greece)	N=121 G=male A=not provided C=not provided R=not provided	Case-control study To investigate the prevalence of lower extremities clinical and radiographic OA in former elite male athletes and referents from the general population and to examine its association with the participants' demographic characteristics.	OA	Questionnaire, clinical and radiological examination	15.7% clinical OA 2.4% clinical hip OA 9.1% clinical knee OA 4.1% clinical ankle OA 40.6% radiographic OA 7.4% radiographic hip OA 16.5% radiographic knee OA 6.6% radiographic ankle OA
Kettunen et al, 199934 (Finland)	N=31 G=male A=56.5 (SD 5.7) C=not provided R=not provided	Case-control study To evaluate lower-limb explosive strength with respect to lifetime athletic activity.	Monthly knee and hip pain, reported knee and hip disability, knee OA, hip OA	Interviews, clinical examinations, quantitative functional measurements, knee x-ray examination, hip MRI	45% knee pain 13% hip pain 35% knee disability 3% hip disability 29% knee OA 12% hip OA
Kettunen et al, 200135 (Finland)	N=90–107 G=male A=48–95 C=not provided R=not provided	Case-control study To determine the relationship between previous lower-limb loading and current self-reported hip and knee disability.	Hip disability, knee disability	Questionnaire	6.5% hip disability 16.7% knee disability
Klünder et al, 198036 (Denmark)	N=57 G=male A=56.4 (40–79) C=22.8 (11–41) R=not provided	Case-control study The purpose of this study was to examine the relationship between top-level football playing over many years and the prevalence of osteoarthritis in the hip and knee joints.	OA, hip OA, knee OA	Radiographs, clinical examination	52.7% OA (controls: 33.3%) 49.1% hip OA (controls: 26.3%) 14.0% knee OA (controls: 12.3%)
Koch et al, 202137 (Germany)	N=126 G=male A=32.2 (SD 4.2) C=25.6 (SD 4.5) R=not provided	Cross-sectional study To investigate the impact of injuries that male professional football players endure during their career, reasons for the end of their career and the postcareer phase of retirement.	Hip OA, knee OA, ankle OA, shoulder OA	Questionnaire	11% hip OA 44% knee OA 35% ankle OA 4% shoulder OA
Krajnc et al, 201038 (Slovenia)	N=40 G=male A=49.2(SD 9.7) C=18.9 (SD 3.8) R=not provided	Cross-sectional study The aim of the study was to evaluate differences in knee injuries and osteoarthritis between the dominant and non-dominant legs of former professional football players.	Symptomatic knee problems (dominant vs non-dominant leg), radiographic knee OA (dominant leg vs non-dominant leg)	History of previous knee injury, knee operations during career, knee radiographs	52.5% subjectively more symptomatic knee non-dominant leg. 25% subjectively more symptomatic knee dominant leg 57.5% radiographic knee OA non-dominant leg 42.5% radiographic knee OA dominant leg >60% radiographic knee OA in one or both knees
Kujala et al, 199439 (Finland)	N=313–178 G=male A=23–76 years C=not provided R=not provided	Case-control study To compare the cumulative 21-year incidence of admission to hospital for osteoarthritis of the hip, knee and ankle in former elite athletes and control subjects.	Admissions to hospital for OA of the weight bearing joints of the lower limb (1970–1990)	Public archives and hospital discharge summaries (1970–1990)	6% admission to hospital for OA in lower limb (controls: 2.6%) 3.2% admission to hospital for hip OA (controls: 1.4%) 2.0% admission to hospital for knee OA (controls: 1.3%) 0.8% admission to hospital for ankle OA (controls: 0%)
Kujala et al, 199540 (Finland)	N=31 G=male A=56.5 (SD 5.7) C=not provided R=not provided	Cross-sectional study To determine the relationship between different physical loading conditions and findings of knee OA.	Knee OA	Questionnaire, interview, clinical examination, knee radiographs	29% knee OA 26% tibiofemoral OA 16% patellofemoral OA 29% knee osteophytes 19% tibiofemoral osteophytes 26% patellofemoral osteophytes 23% subchondral cysts 45% monthly knee pain 35% knee disability 39% extension deficiency
Lindberg et al, 199366 (Sweden)	N=71 G=male A=63 C=not provided R=not provided	Case-control study The aim of the study was to compare the prevalence of hip OA in former soccer players with a randomly selected control group.	Hip OA	Hip radiographs	14.1% hip OA (controls: 4.2%)
Lv et al, 201841 (China)	N=86 G=male A=53 (51-58) C=19.8 (SD 6.3) R=not provided	Case-control study This study aimed to investigate the prevalence of radiographic KOA among retired professional football players by comparing with a control group.	Knee OA	Questionnaire, clinical examination, knee radiographs.	15.1% radiographic knee OA (controls: 45.3%)
Öztürk et al, 200846 (Turkey)	N=70 G=male A=45.64 (SD 8.39) C=11.04 (SD 3.66) R=13.87 (SD 8.39)	Case-control study To examine the occurrence of radiographic changes and abnormalities of the lumbar spine in former professional football compared with a control group.	Osteophytosis of the lumbar spine	Lumbar spine radiographs, Hannover Functional Ability Questionnaire to measure back pain-related disability	27.1% osteophytosis at level T12 (controls: 5.4%) 27.1% osteophytosis at level L1 (controls: 5.49%) 24.3% osteophytosis at level L2 (controls: 7.1%) 29.0% osteophytosis at level L3 (controls: 19.6%) 51.4% osteophytosis at level L4 (controls: 28.6%) 34.3% osteophytosis at level L5 (controls: 19.6%)
Paget et al, 202045 (The Netherlands—Global)	N=401 G=male A=36 (25–50) C=13 (2–19) R=4 (1–17)	Cross-sectional study To determine the prevalence of ankle osteoarthritis among former professional football and rugby players.	Ankle OA	Questionnaire, Health-related QoL using PROMIS-GH	9.2% ankle OA 8.5% ankle OA ≤40 years of age 12.0% ankle OA ≥40 years of age
Paxinos et al, 201642 (Greece)	N=100 G=male A=46.9 (SD 5.9) C=20.52 (SD 7.4) R=not provided	Case-control study To investigate the prevalence of knee OA in retired professional soccer players in comparison with a group of athletically active military personnel.	Knee OA	Questionnaire using medical and sport history, Greek language version of KOOS, clinical examination of both knees, ultrasound examination of both knees	25% clinically evident varus (<178.5°) knee deformity (controls: 22%) 55% knee OA (controls: 33%) 32% knee OA after controlling for knee surgeries (controls: 17%) 44.1% knee OA after excluding participants with history of knee surgery (controls: 25.3%)
Shepard et al, 200367 (UK)	N=68 G=male A=44 (32–59) C=16 (5–25) R=not provided	Case-control study To compare the prevalence of self-reported, physician diagnosed OA of the hip in ex-professional footballers with that in age matched controls in the general public.	Hip OA	Questionnaire	13% OA hip (controls:<1%)
Sortland et al, 198247 (Norway)	N=43 G=male A=49.8 C=not provided R=not provided	Case-control study To investigate the prevalence of degenerative cervical spine changes in a group of retired professional footballers compared with the general population.	Degenerative changes of the cervical spine	Cervical radiographs, clinical examination	32.6% slight or moderate scoliosis (controls: 37.2%) 11.6% healed fractures (controls: 2.3%) 4.7% moderate anterolisthesis at one level (controls: 4.7%) 20.9% history of longstanding cervical complaints; pain and stiffness. 58.1% reduced motion of the cervical spine. 41.1% markedly reduced range of cervical motion
Turner et al, 200043 (UK)	N=284 G=male A=56.1 (SD 11.8) C=13.5 (SD 5.3) R=not provided	Cross-sectional study To describe the long term impact of football on the HRQL of former professional footballers in the UK.	Surgery, joint replacement, OA	Questionnaire about demographics and career details, treatment experience since retirement, OA diagnosis, HRQL using EuroQoL (EQ-5D)	26.4% had surgery since retirement 16.9% had knee surgery since retirement (10 joint replacements) 5.3% had hip surgery since retirement, (12 joint replacements, 6 players had two joint replacements) 8.5% currently awaiting surgery (13 for joint replacement operations; 7 hip, 6 knee) 48.6% diagnosed with OA in at least one anatomical site. 29.2% OA in two or more joints 16.5% bilateral knee OA 14.8% OA in three or more joints 15.1% were registered disabled (33 of which had OA)
Tveit et al, 201249 (Sweden)	N=363–371 G=male A=50–93 years C=20–21 years R=1–63 years	Case-control study To investigate the relationship between intense exercise and subsequent risk of hip and knee OA in athletes.	Knee OA, hip OA, hip arthroplasty, knee arthroplasty	Questionnaire	14.2% hip OA 8.7% hip arthroplasty 18.2% knee OA 3.3% knee arthroplasty
van den Noort et al, 202168 (The Netherlands—Global)	N=401 G=male A=36.5 (SD 5.5) C=52 R=5.3 (4.1)	Case-control study To establish the prevalence of clinical hip osteoarthritis in current and former professional footballers and to explore its consequences on hip function and HRQL.	Hip OA	Questionnaire assessing clinical hip OA, hip function and hip-related quality of life	8% hip OA
Volpi et al, 201969 (Italy)	N=104 G=male A=69.70 (SD 3.20) C=15.31 (SD 3.52) R=not provided	Case-control study To estimate the incidence of hip and knee arthroplasty in Italian male professional football players who have played for a minimum 10 years in the Italian major football leagues.	Hip and/or knee arthroplasty	Questionnaire-based (modified WOMAC questionnaire)	13.5% underwent hip arthroplasty (controls: 0%) 5.8% underwent knee arthroplasty (controls: 1%) 5.8% underwent both hip and knee arthroplasty (controls: 0%) 2.9% underwent arthroplasty in dominant leg 8.6% underwent arthroplasty in non-dominant leg 13.5% underwent arthroplasty in both dominant and non-dominant leg. 7.7% underwent ACL reconstruction and/or meniscectomy (controls: 9%)
Prien et al, 20207 (Germany)	N=49 G=female A=37.2 (SD 4.9) C=9.9 (SD 5.3) R=9.6 (SD 4.0)	Cross-sectional study To assess knee health in retired female football players, using MRI and self-report.	Knee OA	Questionnaire, KOOS, knee MRI	24.5% of knees LFC chondral loss of grade 3 or higher 25.5% of knees MFC chondral loss of grade 3 or higher 31.6% of knees LTP chondral loss of grade 3 or higher 18.4% of knees MTP chondral loss of grade 3 or higher 30.6% of knees substantial tibiofemoral chondral loss 12.2% of knees medial side affected 21.4% of knees lateral side affected 32.7% of knees substantial meniscal loss of grade 3 or higher in lateral meniscus. 32.7% of knees substantial meniscal loss of grade 3 or higher in medial meniscus. 24.5% of knees medial meniscus extrusion >2 mm 25.5% of knees lateral meniscus extrusion >2 mm 51.0% of players substantial tibiofemoral chondral loss 69% of players fulfilled criterion for substantial meniscal loss 59.6% of players fulfilled criteria for substantial knee OA symptoms. 23.4% of players substantial knee OA symptoms only 17% of players substantial chondral loss on MRI only 36.2% of players substantial knee OA symptoms and substantial chondral loss on MRI
Prien et al, 201748 (Germany)	N=152 G=female A=33 (SD 6.19) C=8.6 (SD 5.03) R=not provided	Cross-sectional study The aim of this study was to assess the prevalence of health problems and associated risk factors in former elite female football players.	Physical complaints, knee problems	Questionnaire	81.6% minor to very severe physical complaints in the last 4 weeks 57.9% knee problems while exercising 15.8% (very) severe physical complaints in the last 4 weeks 33.6%–45.4% knee problems during normal daily activities 47.4% spine problems (8.6% severe pain) 46.7% knee problems (9.2% severe pain) 0% of players had an artificial joint replacement. 23.7% diagnosed with OA 13.8% diagnosed with KOA 7.2% diagnosed with AOA

A, age; ACL, anterior cruciate ligament; ACR, American College of Radiology; BMI, body mass index; C, duration of career; EQ-5D, EuroQoL-5 dimension; G, gender; HRQL, health-related quality of life; KL, Kellgren and Lawrence radiological classification; KOOS, knee injury and osteoarthritis outcome score; LFC, lateral femur condyles; LFC, lateral femur condyles; LTP, lateral tibial plateau; LTP, lateral tibial plateau; MFC, medial femur condyles; MFC, medial femur condyles; MTP, medial tibial plateau; MTP, medial tibial plateau; N/n, number of participants; OA, osteoarthritis; PROMIS-GH, Patient-Reported Outcome Measurement Information System Global Health; QoL, quality of life; R, duration of retirement; RKOA, radiographic knee osteoarthritis; SF-36, 36-item short form; TKA, total knee replacement; VAS, visual analogue scale; WOMAC, Western Ontario and McMaster Universities Osteoarthritis Index.