What is Patellofemoral Stabilisation?
Patellofemoral stabilisation is a broad term that refers to surgeries employed for stabilisation (prevention of dislocation) of the patella for the treatment of patellofemoral instability.
Patellofemoral instability means that the patella (kneecap) moves out of its normal pattern of alignment. This malalignment can damage the underlying soft structures such as muscles and ligaments that hold the knee in place. Patellofemoral instability causes pain when standing up from a sitting position and a feeling that the knee may buckle or give way. When the kneecap slips partially or completely you may have severe pain, swelling, bruising, visible deformity, and loss of function of the knee. You may also have sensation changes such as numbness or even partial paralysis below the dislocation as a result of pressure on nerves and blood vessels.
Anatomy of the Patella
The patella is a small piece of bone in front of the knee that slides up and down the groove in the femur bone during bending and stretching movements. The ligaments on the inner and outer sides of the patella hold it in the femoral groove and avoid dislocation of the patella from the groove. The knee can be divided into three compartments: patellofemoral, medial, and lateral compartment. The patellofemoral compartment is the compartment in the front of the knee between the kneecap and thighbone (femur). The medial compartment is the area on the inside portion of the knee, and the lateral compartment is the area on the outside portion of the knee joint.
Indications for Patellofemoral Stabilisation
Patellofemoral instability can be caused because of variations in the shape of the patella or its trochlear groove as the knee bends and straightens. Normally, the patella moves up and down within the trochlear groove when the knee is bent or straightened. Patellofemoral instability occurs when the patella moves either partially (subluxation) or completely (dislocation) out of the trochlear groove.
A combination of factors can cause this abnormal tracking and include the following:
- Anatomical defect: Flat feet or fallen arches and congenital abnormalities in the shape of the patella bone can cause misalignment of the knee joint.
- Abnormal Q angle: A high Q angle (angle between the hips and knees) often results in maltracking of the patella such as in knock knees.
- Patellofemoral arthritis: Patellofemoral arthritis occurs when there is a loss of the articular cartilage on the back of the kneecap. This can eventually lead to abnormal tracking of the patella.
- Improper muscle balance: Weak quadriceps (anterior thigh muscles) can lead to abnormal tracking of the patella, causing it to subluxate or dislocate.
Young, active individuals involved in sports activities are more prone to patellofemoral instability.
Preparation for Patellofemoral Stabilisation
Preoperative preparation for patellofemoral stabilisation surgery will involve the following steps:
- A thorough examination by your doctor is performed to check for any medical issues that need to be addressed prior to surgery.
- Depending on your medical history, social history, and age, you may need to undergo tests such as blood work and imaging to help detect any abnormalities that could threaten the safety of the procedure.
- You will be asked if you have allergies to medications, anaesthesia, or latex.
- You should inform your doctor of any medications, vitamins, or supplements that you are taking.
- You should refrain from medications or supplements such as blood thinners, aspirin, or anti-inflammatory medicines for 1 to 2 weeks prior to surgery.
- You should not consume any solids or liquids at least 8 hours prior to surgery.
- Arrange for someone to drive you home after surgery.
- A written consent will be obtained from you after the surgical procedure has been explained in detail.
Procedure for Patellofemoral Stabilisation
Patellofemoral realignment is surgery employed for patellofemoral stabilisation to treat symptomatic patellofemoral instability. The aim of the surgery is to realign the kneecap in the groove and to decrease the Q angle.
Patellar realignment surgery is broadly classified into proximal re-alignment procedures and distal re-alignment procedures.
- Proximal re-alignment procedures: During this procedure, structures that limit the movements on the outside of the patella are lengthened or ligaments on the inside of the patella are shortened.
- Distal re-alignment procedures: During this procedure, the Q angle is decreased by moving the tibial tubercle towards the inner side of the knee.
The surgery is performed under sterile conditions in the operating room under spinal or general anaesthesia. A larger incision is made over the front of the knee. After visualizing the type and severity of the injury, your surgeon decides on the appropriate surgical correction for it.
A lateral retinacular release may be performed, where your surgeon releases or cuts the tight ligaments on the lateral side (outside) of the patella, enabling it to slide more easily in the femoral groove. Your surgeon may also perform a procedure to realign the quadriceps mechanism by tightening the tendons on the inside or medial side of the knee.
If the misalignment is severe, tibial tubercle transfer (TTT) will be performed. This procedure involves removal of a section of bone where the patellar tendon attaches to the tibia. The bony section is then shifted and properly realigned with the patella and reattached to the tibia with two screws.
Medial patellofemoral ligament (MPFL) reconstruction with graft is another surgery employed for severe patellofemoral instability. This procedure involves fixing a brand new ligament from the medial aspect of the thighbone into the medial aspect of the kneecap. This enhances the medial pull on the kneecap in the earliest phases of knee flexion and guides the kneecap successfully into the trochlear groove.
Once the malalignment is repaired and confirmed, the incisions are closed with sutures and sterile dressings applied.
Postoperative Care and Recovery
In general, postoperative care instructions and recovery after patellofemoral stabilization surgery will involve the following steps:
- You will be transferred to the recovery area where your nurse will closely observe you for any allergic/anaesthetic reactions and monitor your vital signs as you recover.
- You may notice some pain, swelling, and discomfort in the knee area. Pain and anti-inflammatory medications are provided as needed.
- Antibiotics are prescribed as needed to address the risk of surgery-related infection.
- Keep the surgical site clean and dry. Instructions on surgical site care and bathing will be provided.
- You will be placed on crutches for the first few weeks with instructions on restricted weight-bearing. You are encouraged to walk with assistance as frequently as possible to prevent blood clots.
- You are advised to keep your leg elevated while resting to prevent swelling and pain.
- Refrain from smoking as it can negatively affect the healing process.
- Eating a healthy diet rich in vitamin D is strongly advised to promote healing and a faster recovery.
- Refrain from strenuous activities and lifting heavy weights for the first couple of months. Gradual increase in activities over a period of time is recommended.
- An individualised physical therapy protocol is designed to help strengthen your knee muscles and optimise knee function.
- You will be able to resume your normal activities in a couple of months; however, return to sports may take 6 months or more.
- Refrain from driving until you are fully fit and receive your doctor’s consent.
- A periodic follow-up appointment will be scheduled to monitor your progress.
Risks and Complications
Patellofemoral stabilisation is a relatively safe procedure; however, as with any surgical procedure, it does carry some risks and complications, including:
- Persistent pain
- Blood clots
- Anaesthetic/allergic reactions
- Injury to nerves and blood vessels
- Loss of ability to extend the knee
- Recurrent dislocations or subluxations
- Arthrofibrosis (thick fibrous material around the joint)
- The need for revision surgery