20Shoulder Care
AC Joint Injuries
Biceps Tendon Injuries
Calcific Tendinitis
Clavicle Fractures
Frozen Shoulder
Labral and SLAP Tears
Rotator Cuff Injuries
Shoulder Dislocation/Instability
Subacromial Impingement/Busitis
A-C Joint Stabilization
Biceps Tenodesis
Clavicle Fracture Fixation
Pectoralis Major Repair
Rotator Cuff Repair
Shoulder Instability Surgery – Bankart Repair
Shoulder Instability Surgery – Latarjet Procedure
Subacromial Decompression and Acromioplasty
Superior Capsular Reconstruction
Total Shoulder Replacement
28Knee Care
ACL Tear
Cartilage Injury
Lateral Meniscus Tear
LCL Injury
MCL Injury
Medial Meniscus Tear
Patellar Instability
Patellofemoral Chondromalacia
Posterolateral Corner Injury
Trochlear Dysplasia
Anterior Cruciate Ligament (ACL) Reconstruction
Cartilage Restoration Surgery – Autologous Chondrocyte Implantation (ACI-Carticel)
Cartilage Restoration Surgery – Donor Graft
Collagen Meniscal Implant (CMI)
Lateral Collateral Ligament (LCL) Reconstruction
Medial Collateral Ligament (MCL) Reconstruction
Meniscus Repair
Meniscus Root Repair
Meniscal Transplant
Osteochondral Allograft Transfer
Osteochondral Autograft Transfer (OATS)
Partial Meniscectomy
Posterior Cruciate Ligament (PCL) Reconstruction
Posterolateral Corner (PLC) Surgery
Tibial Tubercle Osteotomy
17Hip Care
Cartilage Injury
Femoroacetabular Impingement (FAI)
Gluteal Tears
Hamstring Tears
Hip Instability
Labral Tears
Psoas Impingement (Internal Snapping Hip)
Trochanteric Bursitis
Gluteal Repair
Labral Debridement
Labral Repair
Labral Reconstruction
Trochanteric Bursa Debridement
Bone Marrow Aspirate Stem Cell Concentrate (BMC)
Platelet-Rich Plasma “PRP”


The kneecap (patella) is a small bone in the front of the knee that helps support the extensor mechanism (quadriceps and patellar tendon) that allows people to straighten the knee. As the knee bends, the patella glides along a groove on the femur bone – the trochlea. Patellar instability refers to a condition in which the patella slides out of the trochlea (dislocates). When the patella dislocates, a strong ligament on the inside of the knee (the medial patello-femoral ligament – MPFL) tears completely. Although the MPFL can partially heal without surgery, patients who sustain a patella dislocation are at risk of dislocating the patella in the future. Other injuries that may occur when the patella dislocates include a cartilage injury to the patella or trochlea or a meniscal injury.

There are several factors that are risk-factors for developing patellar instability. One factor is patellar tracking. In some individuals, the patella tracks on the outside of the trochlea instead of in the middle. These individuals may have a high “Q angle,” which indicates that the patellar tendon pulls the patella bone to the outside of the knee. Some individuals also have a shallow trochlear groove (a flat trochlea). When the trochlea groove is shallow or flat, the patella is unstable as the knee bends and can slip out of place (dislocate). Other individuals have very loose ligaments (ligamentous laxity) and are also at risk for developing patellar instability.


  • Severe pain in the knee during a dislocation
  • Sense of kneecap slipping or moving out of place
  • Pain in the front of the knee when squatting, lunging, or with stairs

Diagnosis And Treatment

Dr. Keller considers each patient’s symptoms, as well as a detailed physical examination, x-rays, and sometimes an MRI of the knee to make the diagnosis. Dr. Keller recommends non-surgical management for most patients with patellar instability. A dedicated physical therapy program is a very important part of the treatment plan. Physical therapy focuses on strengthening of the core muscles, hip muscles, as well as the quadriceps. A properly executed physical therapy program can help stabilize the patella. Other non-surgical options for treatment include stabilizing braces, such as hinged brace with a cutout for the patella, oral anti-inflammatory medication, as well as injections, including steroid injections. In those patients who do not improve with non-surgical management, Dr. Keller may recommend surgical intervention of the cartilage lesion AND/OR a soft tissue procedure.