Table 1.

Intrinsic and Extrinsic Factors Examined

Intrinsic factors	Source	Scoring system
Demographic Data
Age, race, gender, height, weight	Self-reported
Living status	Who do you currently live with?	Alone versus Not alone
Subjective Clinical Data
General affect	MHI-5 [46] (a subscale within SF- 36[43])	Index score: 5–25 (5 items each score 1–5)
Symptoms of anxiety/depression	Anxiety/Depression items in EQ- 5D[46]	Item score: 0–2
Expectations of intervention	How much do you expect your treatment (surgery or physical therapy) to improve your quality of life over the NEXT COUPLE YEARS?	Item score: 0–4
Perception of personal health	Current health status subscale of EQ-5D [55]	Item score: 0–100
Clinical symptoms of knee OA	KOOS symptoms subscale[45]	Index score: 0–20
Clinical symptoms of meniscal tear	In the LAST WEEK, have you had any of the following symptoms in your [INDEX] KNEE? Clicking, catching, popping, giving way, locking, swelling, pain with pivoting/twisting?	Yes versus No for each item
Knee pain with specific activities	KOOS pain subscale[45]	Index score: 0–36
General pain	Pain/Discomfort subscale of EQ- 5D[55]	Item score: 0–2
Index knee-related function during athletic activities or specific postures and activities of daily living	SF-36 activities subscale[43]	Index score: 9–27 (9 items scores 1–3)
General function during ADLs and mild physical activity	KOOS function/daily living subscale[45]	Index score: 0–68 (17 items scores 014)
Objective Clinical Data
Need to take oral medication for knee pain	How often do you take each of the following medications for your knee?	Index score: 0–6
Need for intra-articular knee injection(s)	Have you had injections in your knee in the LAST THREE MONTHS?	Yes versus No
Kellgren and Lawrence OA grade on plain films[47]	AP standing plain radiograph reviewed and scored during pre-trial screening by participating physician	Grade 0 – 4
Score on Timed Up and Go test	Timed Up and Go test supervised by physical therapist during pre- trial musculoskeletal exam[48]	Seconds
Score on Quadriceps and Hamstrings manual muscle testing	Manual muscle testing[49] performed and recorded by physical therapist during pre-trial musculoskeletal exam	Average of 3 trials using the manual muscle test hand held dynamometer, pounds
Extrinsic Factors	Source	Scoring system
Annual income	What is your annual household income from all sources before taxes?	Item score: 1–5
Randomization arm	Randomization arm assigned during pre-trial screening by research coordinator (Surgical / Non- Surgical)	Surgery versus Physical Therapy
Highest level of education achieved	What is the highest level of education you have achieved?	Item score: 1–5