Authors: Brian Kwan, Brandon Flaig, Dylan Shafer, Mary Ragsdale
Categories: Case Report, 009
Source: JAAOS Global Research & Reviews
Patellar dislocations commonly occur in young adults and often reduce spontaneously or with closed reduction in the emergency department. However, traumatic patellar dislocations in older adults pose unique challenges, often complicated by degenerative osteophytes that hinder standard closed reduction methods. When closed reduction proves ineffective, patients may necessitate arthroscopic or open surgical intervention. This case report details the experience of a 60-year-old man with a traumatic patellar dislocation resistant to standard closed reduction methods, attributed to impaction of the patella against a lateral femoral condyle osteophyte. We present a novel technique for addressing irreducible patellar dislocations through closed reduction, which has yet to be documented in existing literature.
Acute patellar dislocations constitute 2% to 3% of all knee injuries.^1^ Of all acute dislocations, approximately two-thirds of the patients are active and younger than 20 years.^2^ Patellar dislocations can result from trauma, such as a direct blow to the medial knee or internal twisting of the leg on a planted foot, as well as atraumatic causes, including ligamentous laxity, joint malalignment, or muscular weakness.
Although many cases of patellar dislocations reduce spontaneously, some require closed manipulation or open surgical reduction. Simple patellar dislocations are typically reduced using standard techniques. For lateral patellar dislocations, the standard reduction method involves extending the patient's knee, followed by application of lateral-to-medial force on the patella. However, in cases where closed reduction fails, treatment may require arthroscopic or open surgical intervention, both of which are associated with increased morbidity and cost.^3^
Traumatic patellar dislocations in arthritic knees present a unique clinical challenge. Interlocked osteophytes, along with altered joint mechanics in degenerative knees, may hinder reduction of the patella.^4-6^ These osteophytes often act as a mechanical block to reduction of the patella back into the trochlear groove.
There are limited case reports describing reduction techniques for irreducible, or “locked” patellar dislocations, particularly in older patients or patients with degenerative knee osteoarthritis.^7,8^ Our case presents a novel technique, not previously described in the literature, for the closed reduction of an irreducible lateral patellar dislocation due to impaction of the patella into a lateral femoral condyle osteophyte.
An active and otherwise healthy 60-year-old man presented to the emergency department (ED) with right knee pain and deformity after his right lower extremity was pinned between two cars at low speeds. His history was notable for a right anterior cruciate ligament reconstruction and distal femur osteotomy approximately 40 years prior. On presentation, he had severe pain with weight-bearing and was unable to move his knee through range of motion. Physical examination revealed a deformity suggestive of a lateral patellar dislocation. The knee was held at 15° of flexion, and the patella was palpated laterally. The patient was neurovascularly intact distal to the knee and had no history of patellar instability or dislocation.
Modified radiographs were obtained because of patient positioning and discomfort. They demonstrated a lateral patellar dislocation with diffuse osteophyte formation (Figure 1, A and B). The implant in the distal femur and proximal tibia from the aforementioned surgery was also visualized.
Figure 1 Sunrise (A) and oblique (B) radiographs of the right knee demonstrating a lateral patellar dislocation with a large medial patellar facet osteophyte. Implant in the distal femur and proximal tibia was visualized.
Two ED physicians attempted closed reduction under procedural sedation by using standard reduction techniques, including placing the patient's knee in full extension and applying lateral-to-medial manipulation of the patella. Despite multiple reduction attempts, the patella remained dislocated. Following orthopaedic surgery consultation, a CT scan was performed to better assess bony abnormalities that might prevent reduction. The CT demonstrated a lateral patellar dislocation with impaction of the medial patellar facet on the lateral femoral condyle osteophyte. A fracture of the medial patellar osteophyte was also noted. The impaction of the patella on the lateral femoral osteophyte prevented the mobilization and reduction of the patella (Figure 2, A–C).
Figure 2 A–C, Axial CT cuts of the right knee demonstrating a lateral patellar dislocation with a vertical fracture of the medial patellar facet and osteophyte. The medial patellar facet was affected into an osteophyte on the lateral femoral condyle.
After discussing these findings with the patient, he consented to closed reduction with a novel technique performed by the orthopaedic surgery physician. The patient underwent procedural sedation using intravenous ketamine and midazolam. A final futile attempt at standard reduction was attempted by extending the knee and placing a lateral-to-medial force on the patella. The patella remained locked in a lateral position and was immobile during manipulation. Subsequently, reduction was performed using an alternative and novel technique, which is shown in Figure 3. The hip was flexed to 90° to relax the quadriceps muscles. Concurrently, the knee was hyperflexed, and a medial-to-lateral force was placed on the patella. At approximately 120° of knee flexion, a small palpable shift in the position of the patella was observed. The patella was more mobile and able to be manipulated, suggesting it was unlocked from the osteophyte. The knee was then extended while applying a manual lateral tilt to the patella. A palpable clunk was observed at approximately 10° of knee flexion, with an immediate improvement in the clinical appearance of the knee.
Figure 3 Illustration demonstrating the steps in our novel reduction technique. The hip is flexed to 90° to relax the quadriceps muscles. The knee is then hyperflexed, followed by a medial-to-lateral force placed on the patella. In hyperflexion, the patella should unlock from the femoral condyle osteophyte and become more mobile. The knee is then extended while applying a manual lateral tilt to the patella, along with a lateral-to-medial force, to achieve reduction.
Postreduction radiographs demonstrated successful reduction of the patella (Figure 4, A–C). On examination, the patella remained stable through range of motion, and the extensor mechanism was intact. The patient was placed into a knee immobilizer and made weight-bearing as tolerated. He was discharged with scheduled outpatient follow-up for further treatment. However, the patient resided outside of the area and chose to follow-up elsewhere. Attempts were made for telehealth follow-up. Unfortunately, these were unsuccessful, and no follow-up information was available.
Figure 4 Sunrise (A), lateral (B), and anterior-posterior (C) radiographs of the right knee demonstrating successful reduction of lateral patellar dislocation. A fracture of the medial patellar facet and osteophyte was again visualized, along with diffuse osteophyte formation at the lateral and medial femoral condyles.
Lateral patellar dislocations are common injuries in the younger population. These injuries are generally easily reducible using the standard technique of knee extension and lateral-to-medial force on the patella. Closed reduction of patellar dislocations in older patients may be complicated by patellar impaction, degenerative arthritis, osteophytes, or retained implant. This may lead to an irreducible or locked patellar dislocation, as in our case. We present a novel technique that has not been previously described to aid in the reduction of locked lateral patellar dislocations. This technique involves knee hyperflexion and medial-to-lateral force on the patella, followed by knee extension with lateral patellar tilt.
Several studies have presented alternative reduction techniques for locked patellar dislocations. Aflatooni et al described an alternative reduction technique of a locked lateral patellar dislocation in an adolescent patient.^9^ Their technique used a firm superolateral force on the patella, with the knee extended, to unlock it, followed by a superomedial force to reduce the patella. On review, this method appears successful in patients with no degenerative knee changes. Grewal et al^10^ reported a patient with a lateral patellar dislocation that failed multiple attempts at closed reduction. Under general anesthesia, their technique required 20 minutes of firm pressure on the lateral patella while lifting it anteriorly and medially to achieve closed reduction. They thought that an incarcerated fat pad was blocking reduction, and their technique allowed for alleviation of this blockage.
Failed closed reduction may require acute surgical intervention to achieve reduction. Delagrammaticas et al reported a case of a locked patellar dislocation that also failed multiple attempts at closed reduction, as well as attempted percutaneous reduction with bone reduction forceps in the ED under sterile conditions.^11^ Their patient required open reduction in the operating room, which revealed that the patella was incarcerated in the lateral patellar retinaculum and locked against the lateral femoral condyle. After release of the incarcerated tissues, successful reduction of the patella occurred. Similarly, Tanos et al^7^ reported a case of a patellar dislocation that failed closed reduction and percutaneous reduction with a pointed reduction clamp. The patient underwent arthroscopy, and using a probe to provide leverage, the lateral border of the patella was lifted from the lateral femoral condyle, permitting reduction. Yerimah et al^12^ described a case of a traumatic patellar dislocation that failed closed reduction and subsequently required open reduction. In the operating room, open exploration revealed that an osteochondral defect on the medial patella was affected and ‘keyed-in’ to the lateral femoral condyle, preventing closed reduction. This is similar to the injury in our case, based on its appearance on the axial CT images shown in Figure 2, A and B. However, their patient required open reduction in the operating room.
Most case reports describing irreducible patellar dislocations have been in the adolescent or young adult population.^9-12^ There is a paucity of literature discussing management of locked patellar dislocations in knees with degenerative changes. Phaltankar et al reported a case of an irreducible lateral patellar dislocation in an adult knee with degenerative changes.^8^ Imaging revealed an impaction fracture of the medial facet of the patella, which was locked on the lateral femoral condyle, preventing closed reduction. Because of the preexisting tricompartmental degenerative changes in the knee, they elected to treat with a total knee arthroplasty with several concomitant soft-tissue procedures to achieve adequate patellar tracking.
Beyond the standard technique, there are a few described alternative techniques for the closed reduction of irreducible patellar dislocations. In addition, other reported cases present surgical interventions in the form of open reduction or arthroplasty as treatments for locked patellar dislocations. This is the first case in the literature describing an irreducible lateral patellar dislocation in a degenerative knee treated with closed reduction. We believe that our case report and novel reduction technique add to the current literature on managing locked patellar dislocations, particularly in patients with degenerative knee changes.
This case illustrates that osteophytes in the patella or femoral condyle can prevent reduction. Irreducible lateral patellar dislocations in degenerated knees often require arthroscopic or open surgical reduction. However, these unique injuries may be reduced in a closed manner using our novel technique when standard techniques are unsuccessful.
Patellar dislocations in degenerative knees often require arthroscopic or open surgical reduction. However, these injuries may be managed with a novel technique for closed reduction.
Brandon Flaig, Email: bflaig79@gmail.com.
Dylan Shafer, Email: dshafer@cmhshealth.org.
Mary Ragsdale, Email: mragsdal@gmail.com.