The NUsurface® Meniscus Implant Randomized Study is a multi-center, prospective randomized, interventional clinical trial to test the hypothesis that the NUsurface implant is superior to the non-surgical standard of care in treating the target population.The rationale for performing this clinical study is to gather clinical data to evaluate the safety and effectiveness of the NUsurface device compared to the Standard of Care.

The NUsurface® Meniscus Implant is intended for use in patients with medial compartment pain that have had a previous partial medial meniscectomy.

Patients who meet the inclusion/exclusion criteria will be assigned by balanced randomization into one of two groups: the Meniscus Implants versus non-surgical standard of care. The KOOS (Knee injury and Osteoarthritis Outcome Score) and IKDC (International Knee Documentation Committee) forms will be used to provide a comprehensive evaluation of the patients' pre-intervention and post-intervention condition including activity levels, pain, swelling, locking, stability, support, sports activity, and quality of life assessment.

Inclusion Criteria:

• Had > 6 months ago a medial partial meniscectomy as confirmed by patient history and MRI
• Is between age 30 and 75 years (inclusive) at the time of study treatment
• Has neutral alignment ±5º of the mechanical axis, as measured from the angle formed by a line drawn from the center of the femoral head to the medial tibial spine and a line drawn from the medial tibial spine and the center of the ankle joint
• Has ≥ 2 mm intact medial meniscal rim capable of being fitted with a NUsurface® device AND is also recommended for the baseline non-surgical (and, if likely to receive benefit, any injection) therapies to be administered in the study.
• Is willing to be entered into either arm of the study: implanted with the NUsurface device OR treated with the recommended control arm therapies.
• Is willing and able to attend all follow up visits, complete all study questionnaires, and undergo required X-ray and MRI schedule
• Is able and willing to understand and sign the Informed Consent Form
• Is able to read and understand the English language
• Has a KOOS Pain of ≤ 75 (100 being the highest attainable and no pain)

Exclusion Criteria:

• Has a symptomatic knee because of a tear that could be addressed by a repeat partial meniscectomy leaving > 4 mm of medial meniscus rim
• Has evidence of a Outerbridge Grade IV cartilage loss on the medial tibial plateau or femoral condyle that potentially could contact a NUsurface implant (e.g., a focal lesion > 0.5 cm2 correlating to a circular defect of > 8 mm in diameter)
• Has complete disruption of the posterior root attachment of the meniscus
• Has lateral compartment pain and Grade III or Grade IV Outerbridge cartilage score in the lateral compartment
• Has a varus or valgus knee deformity > 5º requiring a tibial or femoral osteotomy
• Has a laxity level of more than Grade II (IKDC), primary or secondary to an injury of the anterior cruciate ligament (ACL) and/or posterior cruciate ligament (PCL) and/or lateral collateral ligament (LCL) and/or medial collateral ligament (MCL)
• Has significant trochlear dysplasia, patellar instability or symptomatic patellar misalignment
• Has patellar compartment pain and Grade III or Grade IV Outerbridge cartilage score in the patellar compartment.
• Compared to a normal knee, has obvious radiological evidence of medial femoral squaring, anatomical variance in the medial tibial plateau, or irregularly shaped cartilage surface
• Had an ACL reconstruction performed < 9 months prior to study treatment
• Has a BMI > 32.5 at the time of study treatment
• Decides to receive (if eligible and an option) allograft medial meniscus transplantation
• Received any type of prosthetic knee implant made of artificial non-resorbable plastic, metal or ceramic, not including the NUsurface® Meniscus Implant
• Has a knee flexion contracture > 10º
• Has flexion < 90º
• Had a previous medial femoral condyle surgery (not including microfracture) or High Tibial Osteotomy (HTO)
• Has insufficiency fractures or avascular necrosis of the medial compartment
• Has an active infection or tumor (local or systemic)
• Has any type of knee joint inflammatory disease including Sjogren's syndrome
• Has neuropathic knee osteoarthropathy, also known as Charcot joint
• Has any medical condition that does not allow possible arthroscopy of the knee
• Has neurological deficit (sensory, motor, or reflex)
• Is currently involved in another investigation of the lower extremity
• Anticipates having another lower extremity surgery during the study period
• Is contraindicated for hyaluronic acid injections (i.e., patients with known hypersensitivity [allergy] to hyaluronan [sodium hyaluronate] preparations); patients having knee joint infections or skin diseases or infections in the site of possible injections
• Is contraindicated for corticosteroid injections (i.e., patients with allergy to any of the components or with idiopathic thrombocytopenic purpura)
• Has received any corticosteroid knee injections ≤ 3 months prior to study treatment
• Has chondrocalcinosis
• Is on immunostimulating or immunosuppressing agents
• Has ipsilateral or contralateral lower limb joint conditions that may affect ambulation or KOOS (e.g. have a leg length discrepancy > 2.5 cm [1 inch], causing a noticeable limp)
• Is a female who is lactating, expecting, or is intending to become pregnant during the study period
• Is an active smoker
• Is mentally incapacitated (incapable of appraising or controlling conduct) or have mental disability (e.g., dementia or Alzheimer's)
• Is a prisoner
• Is a patient who has economic incentive not to improve