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Table 1 Design characteristics of included studies

From: Anterior knee pain in younger adults as a precursor to subsequent patellofemoral osteoarthritis: a systematic review

Author, year of publication Design Setting Sampling procedure AKP method of ascertainment, definition PFOA method of ascertainment, definition Length of follow-up
Utting et al 2005 [18] Retrospective unmatched case-control. Hospital orthopaedic surgery (Bristol, UK). Local arthroplasty database (?period).
Cases
Isolated PF arthroplasty for severe isolated PFOA.
Controls
medial TF unicompartmental arthroplasty.
Self-complete questionnaire.
Recall of AKP as a child, teenager, or young adult.
Severe isolated PFOA requiring patellofemoral arthroplasty. -
Kannus et al 1999 [19] Prospective follow-up of RCT. Hospital orthopaedic outpatients (Tampere, Finland). Consecutive patients with unilateral PFPS enrolled in RCT of conservative therapy (1987-1990). Clinical interview, examination and plain x-ray.
Retropatellar pain and crepitus with no other knee abnormalities.
Plain x-rays (AP, lateral, tunnel, tangential) and MRI.
PFOA classified as none, mild, moderate, or severe for each imaging modality.
Mean 6.6 years.
Nimon et al 1998 [20] Prospective follow-up of case series. Hospital orthopaedic outpatients (Oxford, UK). Consecutive adolescent female patients with idiopathic AKP (1974-1980). Clinical history, examination, plain x-ray.
No specific definition provided (other definitive diagnoses excluded, all complained of pain on ascending/descending stairs, squatting, or prolonged sitting).
Plain x-rays (AP, lateral, skyline).
No specific definition provided.
Mean 16 years (range 14-20).
Imhoff & Boni 1989 [21] Prospective follow-up of two case series. Orthopaedic outpatients, (Zurich, Switzerland). ?consecutive patients with PF pain undergoing conservative or surgical treatment (1953-1968). Unclear.
No specific definition provided.
Plain x-rays (views not specified).
Films scored using a 4-point radiographic definition, based on that of Jäger & Wirth [25].
Mean 23 years.
Hvid et al 1981 [22] Prospective follow-up of case series. Hospital orthopaedics/diagnostic radiology
(Nykøbing, Denmark).
Patients with chondromalacia patellae on arthrography (1972-1977). Clinical history, physical examination, and arthrogram.
No specific definition provided.
"a significant clinical syndrome" of chondromalacia patellae.
Plain x-rays (frontal, lateral, axial [26]).
No specific definition provided ("signs of arthrosis were searched for on all films")
Mean 5.7 years.
Dexel et al 1980 [23] Prospective follow-up of two case series. Orthopaedic outpatients, (Zurich, Switzerland). ?consecutive patients with PF pain undergoing conservative or surgical treatment (1953-1968). Unclear.
No specific definition provided.
Plain x-rays (views not specified).
4-point radiographic definition, based on that of Tapper & Hoover [27].
Mean 13 years.
Karlson 1939 [24] Prospective follow-up of comparative case series. Hospital orthopaedics
(Stockholm, Sweden).
? consecutive male patients (mostly army conscripts) with "simple chondromalacia patellae" of both traumatic and non-traumatic origin
(1917-1934).
Clinical history and physical examination.
No specific definition provided.
Plain x-rays (views not specified).
No specific definition provided ("arthritis deformans").
Mean 5.9 years (range 1-20).
  1. AKP Anterior knee pain; AP Anteroposterior; PF Patellofemoral; PFOA Patellofemoral osteoarthritis; PFPS Patellofemoral pain syndrome; RCT Randomised controlled trial; TF Tibiofemoral