You can ask the person who had their first knee dislocation out on the field how it felt and 9 times out of 10 they will tell you it was a memorable experience. I can guarantee you the story usually involved a green whistle and a stretcher to the hospital. For those athletes who experience repetitive knee dislocations? That is another whole can of worms. Let’s talk about what patellar or knee dislocation is, what structures are involved, the treatment and management pathway that can be taken to help you return to play.
What is it?
Patellar dislocation occurs when the patella or kneecap is displaced out of its confinement which is the trochlea groove of the femoral condyle (thigh bone). Acute dislocation is usually followed by traumatic incidents such as a blow to the knee during a rugby tackle or strenuous pivoting in netball or lacrosse. Immediately after the incident, you can expect haemarthrosis (bleeding into the joint) and mild to moderate oedema (swelling).
Figure 1. Patellar deviating outwards further than its neutral zone due to external force
Structures involved
The medial patellofemoral ligament is the primary stabilizer against this lateral deviation (outward motion) of the patella, providing up to 53% to 67% of the medial soft tissue restraint. When excessive motion occurs at the knee during sports, this ligament acts as a passive restraint or like a seatbelt preventing the patellar from further displacement.
In most cases, the vastus medialis muscle (part of the quadriceps group) tends to be involved as well due to the location of the medial patellofemoral ligament lying directly adjacent to it. In rare and severe cases, osteochondral avulsion fracture can happen where the ligament pulls and disrupts the surface of the articular cartilage and subchondral bone plate.
Figure 2. Red arrow indicating the direction of dislocation and potential structures (highlighted yellow) involved
Acute to chronic
Due to the potential structures involved in a patellar dislocation, it has been estimated that the dislocation rate is as high as 15-44% with a non-operative approach. Losing passive structures holding the patellar within its neutral zone, especially trying to perform in a competitive setting, can be quite debilitating due to its recurrent rate. Therefore, rehabilitation is very important to help athletes return to play with increased confidence.
Signs and Symptoms
Complaint of pain on twisting or jumping
Sudden giving way with severe pain
Sensation of the knee “moving away” or “popping out”
Immediate swelling after an episode
The majority of cases relocate after extending the knee straight; for those that don’t relocate will require some medical assistance and regional anesthesia from health professionals
Treatment
Phase 1 - Week 0-2: During this phase, the treatment goal is to control swelling, maintain knee extension, and develop isometric quadriceps strength. The typical exercises we prescribe during this phase are:
Quadriceps: inner range quads, straight leg raise
Calf raises
Hip abduction
Phase 2 - Week 2-6: During this phase, the goal is to have no swelling in the knee, normal knee extension and up to 100 degrees flexion, <10-15% strength difference in quadriceps and hamstrings. The exercises we may prescribe are:
Active ranging
Bridging with ball squeeze then single leg bridging
Mini-squats then mini-lunges
Resisted hip abduction and extension
Single calf raise
Single leg balance
Phase 3 - Week 6-8: The goal of this phase is to reach normal movement and strength, return to jogging, running, agility, and restricted sports-specific drills. The exercises we may prescribe here depend on the sport, here are some examples:
Progress as phase 2 but with increased resistance/load and repetitions
Single-leg squats
Single-leg press
Jump and land drills
Agility drills
Phase 4 - Week 8-12: Here we're focused on returning to sport / play preparations. The exercises here are sport-specific strengthening as required.
Patellar dislocation can be a daunting experience, especially with returning to play as it affects your confidence and performance. Proper rehabilitation is definitely the way to boost your confidence with your return to play and if you have any questions, please do not hesitate to contact us and book an appointment!
By Eric Chao, Senior Physiotherapist, Breathe Physio and Pilates
Shop 5, 66 Slobodian Avenue, Eight Mile Plains
Brisbane, Queensland, Australia.