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. 2022 Mar 3;2022(3):CD014328. doi: 10.1002/14651858.CD014328

Katz 2013.

Study characteristics
Methods Study design: multicentre, parallel‐group, two‐arm, randomised, controlled trial
Setting: seven US tertiary referral centres ‐ Brigham and Women’s Hospital, Boston; Hospital for Special Surgery, New York; Cleveland Clinic, Cleveland; Vanderbilt University, Nashville; Mayo Clinic, Rochester; Rush University Medical Center, Chicago; Washington University, St. Louis, USA
Trial time period: participants were enrolled between June 2008 and August 2011
Interventions: arthroscopic surgery plus supervised physical therapy versus supervised physical therapy
Sample size calculations: the study was powered to detect a 10‐point difference on the WOMAC functional scale between the operative and non‐operative arms, The study team adopted a Type I error rate of 5% and power of 80% and the target sample size was set at 340 participants. The sample size calculation took into account two sources of sample degradation: losses to follow‐up and cross‐over from the assigned arm to the other arm prior to the primary outcome assessment at six months. The study was also powered for one pre‐planned subgroup analysis in which participants with Kellgren‐Lawrence (KL) Grade 3 (joint space narrowing) would be analysed in one subgroup and those with KL Grades 0 to 2 in the other.
Analysis: outcome analysis only included participants who did not withdraw from the study.
Participants Number of participants

  • Number screened: 14,430 (12,008 did not meet inclusion criteria, 1092 not screened by physician, 195 eligible but not referred, 784 declined to participate)

  • Number of participants at enrolment: 351

  • Number randomised: 351: 174 in the arthroscopy group and 177 in the physical therapy group. 51 crossed over to surgery group at 6 months and 59 crossed over to surgery group at 12 months

  • Number included in analyses: 330: 161 in the arthroscopy group and 169 in the physical therapy group (at 6 months), and 320; 156 in the arthroscopy group and 164 in the physical therapy group (at 12 months)


Criteria for defining knee osteoarthritis with meniscal tear: symptomatic participants 45 years of age or older with a meniscal tear and evidence of mild‐to‐moderate osteoarthritis on imaging
Inclusion criteria.

  • Symptoms for at least four weeks, managed with one or more of: medications, activity limitations or PT

  • Symptoms consistent with torn meniscus (at least one of: clicking, catching, popping, giving way, pain with pivot or torque, pain that is episodic, pain that is acute and localised to one joint line)

  • Availability of knee radiograph and MRI

  • Evidence on knee MRI of osteophytes or full‐thickness cartilage defect; or plain radiographic evidence of osteophytes or joint space narrowing

  • Evidence on knee MRI of a meniscal tear that extends to the surface of the meniscus

  • Willingness to undergo randomisation and ability to understand and sign an informed consent document


Exclusion criteria

  • A chronically locked knee (e.g. participant cannot reduce locking; a clear‐cut indication for arthroscopic partial meniscectomy)

  • Kellgren‐Lawrence Grade 4 (far advanced OA)

  • Inflammatory arthritis or clinically symptomatic chondrocalcinosis

  • Injection with viscosupplementation in past four weeks in index knee

  • Contraindication to surgery or physical therapy

  • Bilateral symptomatic meniscal tears

  • Prior surgery on same knee


Baseline characteristics
Arthroscopic Partial Meniscectomy (N = 161)

  • Mean (SD) age: 59.0 (7.9) years

  • Number of men and women: M/F = 71/90

  • Treatment history: pharmacological and physical therapy

  • Concurrent treatment: NSAIDs, acetaminophen, intra‐articular glucocorticoids

  • Mean (SD) body‐mass index: 30.0 (6.1)

  • Mean (SD) WOMAC physical‐function score: 37.1 (17.9)

  • Mean (SD) KOOS pain score: 46.0 (15.5)

  • Mean (SD) Mental Health Index 5 score: 74.8 (12.9)

  • Mean (SD) SF‐36 physical‐activity score: 44.3 (23.7)

  • Kellgren–Lawrence grade — no. (%): 0‐ 34 (21.1); 1‐ 26 (16.1); 2‐ 37 (23.0); 3‐ 45 (28.0)


Physical Therapy (N = 169)

  • Mean (SD) age: 57.8 (6.8 years)

  • Number of men and women: M/F = 72/97

  • Treatment history: pharmacological and physical therapy

  • Concurrent treatment: NSAIDs, acetaminophen, intra‐articular glucocorticoids

  • Mean (SD) body‐mass index: 30.0 (6.1)

  • Mean (SD) WOMAC physical‐function score: 37.5 (18.3)

  • Mean (SD) KOOS pain score: 47.2 (16.4)

  • Mean (SD) Mental Health Index 5 score: 74.0 (13.9)

  • Mean (SD) SF‐36 physical‐activity score: 43.3 (23.3)

  • Kellgren–Lawrence grade — no. (%): 0‐ 36 (21.3); 1‐ 35 (20.7); 2‐ 39 (23.1); 3‐ 39 (23.1)


Pre‐treatment group differences: no differences were reported between the two groups.
Interventions Arthroscopic surgery
Arthroscopic partial meniscectomy plus physical therapy. The damaged meniscus was trimmed back to a stable rim. Loose fragments of cartilage and bone were removed without any penetration of the subchondral bone. Preoperative antibiotics were used routinely.
Postoperatively, participants were allowed to bear weight as they were able. Bracing was not used. Participants were referred to a physical therapist for a postoperative standardized physical therapy program, as described below.
Exercise:
Supervised physical therapy provided to both groups.
Phase I‐Acute Phase (1‐10 days post‐op)
8 exercises, 12‐15 repetitions, 1‐2 sets of the following types of exercises:

  • Decrease Inflammation: Retrograde Massage, Cryotherapy E‐Stim: NMES or IFC

  • Manual Therapy: Joint Mobilization Soft Tissue Mobilization Stretching LE Muscles

  • Open Chain Exercises: Quad Sets SAQ/LAQ/HS Curls Hip‐4 way

  • Closed Chain Exercises: Bicycle, Elliptical, Treadmill, Leg Press, Balance/Proprioception


Phase II‐Subacute Phase (10 days ‐ 4 weeks post‐op)
Participant must meet 3 of the 4 criteria: Knee A/PROM 0>=115 degrees, moderate to minimal effusion, knee Pain = 3/5)
8 exercises, 12‐15 repetitions, 1‐2 sets of the following types of exercises:

  • Decrease Inflammation: Retrograde Massage Cryotherapy E‐Stim: NMES or IFC

  • Manual Therapy: Joint Mobilization Soft Tissue Mobilization Stretching LE Muscles

  • Open Chain Exercises: Add more Concentric/Eccentric Hip/Knee progressive resistive exercises, ROM

  • Closed Chain Exercises: Resisted terminal knee extension, modified mini squats, step up/down progressions, toe raises, functional and agility training


Phase III‐Advanced Activity Phase (4‐7 weeks post‐op)
8 exercises, 12‐15 repetitions, 1‐2 sets of the following types of exercises:

  • Continued stretching program

  • Continued PRE therapeutic exercises program

  • Emphasis on closed chain program with progression to dynamic single leg stance, plyometrics, running, and sport specificity training


In both the arthroscopic partial meniscectomy plus physical therapy and physical therapy alone groups, participants were permitted to receive acetaminophen and non‐steroidal anti‐inflammatory agents as needed, and intra‐articular injections of glucocorticoids were permitted over the course of the trial.
Outcomes Outcomes were measured at baseline and at 3 and 6 months and every 6 months thereafter up to 5 years follow‐up (protocol states outcomes measured at baseline, 3, 6, 12, 18 and 24 months, but data in published papers report outcomes at baseline, 6 and 12 months and up to 5 years. Authors did not respond to requests for data).
Primary outcome
Physical function on the physical‐function scale of the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) assessed at 6 months. Scores range from 0 to 100, with higher scores indicating worse physical function
Secondary outcomes

  • Pain and symptoms measured on the Knee Injury and Osteoarthritis Outcome Scale (KOOS) Pain and Symptoms subscales respectively. Scores range from 0 to 100, with higher scores indicating more pain (data on KOOS symptoms subscale not reported)

  • SF‐36 Physical Activity subscale. Scores range from 0 to 100, with higher scores indicating greater physical activity

  • Treatment success ‐ improvement in the WOMAC physical‐function score of at least 8 points (defined as a clinically relevant difference specified a priori)

  • Mental health status measured on MHI‐5 (5‐Item Mental Health Index). Scores range from 0 to 100, with higher scores indicating better mental health

  • Physical examination ‐ quadriceps strength, passive and active knee extension and flexion, gait disturbance, balance, proprioception and functional limitation (measured at baseline and 3 months only) (data not reported)

  • Generic health‐related quality of life measured on the EQ‐5D (data not reported)

  • Adverse events

  • Knee joint replacement

  • Medical comorbidity measured on the Self Administered Comorbidity Questionnaire (data not reported)

  • Health care utilisation ‐ hospitalisations, medications, assistive devices, tests, procedures and visits to physicians, physical therapists and other providers, direct non‐medical costs (incl. transportation to appointments, time and expenses involved in receiving care), indirect costs (lost wages, time off work) (data not reported)


Outcomes included in this review at 3, 6 and 24 months and 5 years

  • Pain measured on KOOS Pain subscale (0 to 100, lower score = less pain)

  • Function measured on WOMAC Physical Function scale (0 to 100, lower score = better function) (we multiplied the mean values by –1 so that higher scores = better function, as per Cochrane Handbook guidance, so direction was consistent across function scales)

  • Participant‐reported success measured as improvement in the WOMAC Physical Function score of at least 8 points

  • Knee surgery ‐ self‐report in questionnaire and medical record review

  • Serious adverse events

  • Total adverse events
Notes Funding: this study was funded by grants (R01AR055557, K24AR057827, and P60AR047782) from the National Institute of Arthritis and Musculoskeletal and Skin Diseases of the National Institutes of Health.
Trial registration: ClinicalTrials.gov number, NCT00597012 (METEOR study)
Adverse Events
Arthroscopic partial meniscectomy (APM):
Serious adverse events ‐ no. (%)

  • Cardiovascular ‐ 2 (1.15%) (Pulmonary embolism resulting in death‐ 1; Acute myocardial infarction ‐1)

  • Vascular disorders (Hypoxemia) ‐ 1 (0.57%)

  • Knee replacement ‐ 5 (2.8%)


Total serious adverse events ‐ 8/164 (4.9%)
Other adverse events ‐ no. (%)

  • Cardiovascular ‐ 6 (3.45%) (Deep vein thrombosis ‐ 2; syncope ‐ 1; skin ‐ 2; other ‐1)

  • Musculoskeletal ‐ 7 (4.02%) (Pain from fall or other trauma ‐ 2; tendonitis ‐ 3; rupture of baker's cyst ‐ 1; knee pain ‐ 1)

  • Pain in the back, hip, or foot ‐ 2 (1.15%)


Total other adverse events ‐ 15 (8.62%)
Total ALL adverse events ‐ 23/164 (14.0%)
Physical therapy (PT):
Serious adverse events ‐ no. (%)

  • Cardiovascular‐ 2 (1.13%) (Stroke ‐ 1; Sudden death ‐ 1)

  • Knee replacement ‐ 3 (1.7%)


Total serious adverse events ‐ 5/109 (4.59%)
Other adverse events ‐ no.(%)

  • Cardiovascular ‐ 3 (1.69%) (Atrial fibrillation ‐ 1; skin ‐1; other ‐1)

  • Musculoskeletal ‐ 6 (3.39%) (Pain from fall or other trauma ‐ 4; knee bursitis ‐ 1; knee pain ‐ 1)

  • Pain in the back, hip, or foot ‐ 4 (2.26%)


Total other adverse events ‐ 13 (7.34%)
Total ALL adverse events ‐ 18/109 (16.5%)
There was no group differences in the frequency of adverse events.
Knee surgery (replacement or osteotomy) (12 months' follow‐up):
Arthroscopic Partial Meniscectomy:
No. of participants = 5 (2.8%)
Physical Therapy:
No. of participants = 3 (1.7%)
Knee surgery (replacement or osteotomy) (5 years' follow‐up):
Randomised to and receiving Arthroscopic Partial Meniscectomy:
No. of participants = 16/164 (9.8%)
Cross‐overs from Physical Therapy to Arthroscopic Partial Meniscectomy:
No. of participants = 7/68 (10.3%)
Randomised to and receiving Physical Therapy:
No. of participants = 2/109 (1.8%)
Progression of knee OA: not reported
Withdrawals: 7/174 from APM group and 4/177 from physical therapy group at 6 months and 9/174 from the APM group and 7/177 from physical therapy group at 12 months
Report of study results: Attempts to obtain KOOS Pain and WOMAC PF 5‐year follow‐up data from authors were unsuccessful. For total knee replacement, adverse events and serious adverse events, we reported 109 in the PT group (i.e. those who did not cross over to APM).
Risk of bias
Bias Authors' judgement Support for judgement
Random sequence generation (selection bias) Low risk "Randomisation was done using a secure program on the trial website" in blocks of varying size within each site, stratified by the extent of osteoarthritis at baseline (Kellgren‐Lawrence grade 0–2 (no joint space narrowing) versus Kellgren‐Lawrence grade 3 (< 50% joint space narrowing). Probably low risk
Allocation concealment (selection bias) Low risk Randomisation was performed by a research coordinator in real time using a secure website, thus ensuring concealment until the time of allocation to treatment group
Blinding of participants and personnel (performance bias)
All outcomes High risk "Our study was not blinded, since our investigative group did not consider a sham comparison group feasible"
Blinding of outcome assessor
Self‐reported outcomes High risk As participants were aware of their treatment, assessment of self‐reported outcomes including WOMAC and KOOS were at risk of detection bias
Blinding of outcome assessor
Assessor‐reported outcome (knee replacement) High risk Radiographs of the knee were assessed by surgeons (who were aware of the treatment assignment) as well as musculoskeletal radiologists, whose knowledge of treatment assignment is not reported. KL grading and assessment of radiographs are subject to bias as blinding of outcome assessors was not done
Incomplete outcome data (attrition bias)
All outcomes Low risk The proportion of loss to follow‐up and reasons for incomplete outcome data are similar between groups
Selective reporting (reporting bias) High risk SF‐36 5‐item mental health index and EQ‐5D were measured, according to the protocol paper, but were not listed as outcomes in the trial registration form. No results data for these outcomes are available
Other bias Unclear risk 33.8% (60/177) of participants assigned to physical therapy crossed over to arthroscopy within 6 months of randomisation, but their outcome data for pain, function and treatment success was included in the analysis for the physical therapy group potentially underestimating any effect of surgery