Case Report

Arthroscopic Excision of Bipartite Patella With Preservation of Lateral Retinaculum in an Adolescent Ice Hockey Player

Author and Disclosure Information

Bipartite patella usually is an asymptomatic anatomical variant. However, in some adolescent athletes, it causes anterior knee pain, resulting in decreased participation and performance. We report the case of a high-level adolescent ice hockey player who underwent successful arthroscopic excision with preservation of the lateral retinaculum of a symptomatic bipartite patella after failed nonoperative treatment. The patient returned to play by 6 weeks, and 31-month subjective follow-up scores showed high satisfaction and good clinical outcomes. For patients with a symptomatic bipartite patella, arthroscopic surgery is a good option for reducing pain and returning the athlete to competition.



Take-Home Points

  • Bipartite patella is an asymptomatic anatomical variant.
  • Occasionally, some adolescent athletes can present with AKP, resulting in decreased participation and performance.
  • Bipartite patella is classified in type I, inferior pole; type II, lateral margin; and type III, superior lateral pole, depending on where the accessory patellar fragment is.
  • Nonoperative treatment is advocated first. If symptoms persist surgical treatment should be attempted.

In 2% to 3% of the general population, the finding of bipartite patella on knee radiographs is often incidental.1,2 During development, the patella normally originates in a primary ossification center. Occasionally, secondary ossification centers emerge around the margins of the primary center and typically join that center. In some cases, the secondary2 center remains separated, leading to patella partita and an accessory patellar fragment.3,4

The bipartite patella is connected to the primary patella by fibrocartilage. The fibrous attachment may become irritated or separated as a result of trauma, overuse, or strenuous activity.1,5-7 Saupe classification of bipartite patella is based on accessory patellar fragment location: type I, inferior pole; type II, lateral margin; and type III, superior lateral pole.8 When an individual with a bipartite patella becomes symptomatic, anterior knee pain (AKP) is the most common complaint—it has been described in adolescent athletes in numerous sports.7,9-11For most patients, first-line treatment is nonoperative management. A typical regimen includes reduced activity, use of nonsteroidal anti-inflammatory drugs, physical therapy, and isometric quadriceps-strengthening exercises.1,12 Other nonoperative approaches described in the literature are immobilization,5,10 steroid and anesthetic injection, and ultrasound therapy.13 If symptoms do not improve, surgical treatment should be considered. Surgical treatment options include open excision of fragment,3,9,12 arthroscopic excision of fragment,7,14,15 tension band wiring,5,16 open reduction and internal fixation,17 open or arthroscopic vastus lateralis release,18-20 and lateral retinacular release.21 However, the optimal surgical option remains controversial.

In this case report, we present a modification of an arthroscopic surgical technique for excising a symptomatic bipartite patella and report midterm clinical outcomes. The patient provided written informed consent for print and electronic publication of this report.

Case Report

A 16-year-old elite male ice hockey player presented to clinic with a 2-week history of left AKP. He could not recall a specific injury that triggered the symptoms. Radiographs were obtained at an outside institution, and knee patellar fracture was diagnosed. The patient, placed in a straight-leg immobilizer, later presented to a referral clinic for a second opinion and further evaluation. Physical examination revealed significant tenderness to palpation of the lateral aspect of the patella. Range of motion was symmetric and fully intact. Patellar mobility was excellent. However, the patient could not perform a straight-leg raise because of the pain.

We obtained anteroposterior and lateral radiographs (Figures 1A, 1B), which showed evidence of a Saupe type III bipartite patella with separation at the superolateral pole.

Figure 1.
A magnetic resonance imaging (MRI) series was ordered for further evaluation of the soft tissues (Figure 2).
Figure 2.
There was bony edema in the anteromedial aspect of the distal femur. The visualized patella showed no evidence of fracture, though there was evidence of disruption through the fibrous attachments of the bipartite patella fragment. Physical therapy (range-of-motion exercises, quadriceps sets, and stationary bicycling) was initiated. By 6 weeks, the patient’s discomfort had resolved, and he resumed on-ice activities as tolerated.

Two years later, the patient returned with left AKP, again localized to the lateral aspect of the patella, over the bipartite fragment. The pain was significant with compression. Given the patient’s history, arthroscopic excision of the bipartite patella was recommended. After discussing all treatment options, the patient elected to proceed with the surgery.

Surgical Technique

The patient was positioned supine on the operating table. Medial and lateral parapatellar arthroscopic portals were created. Menisci, cruciate ligaments, and tibiofemoral articular cartilage were arthroscopically visualized and determined to be normal. The bipartite patella was easily visualized, and notably loose when probed. Grade 2 chondromalacia was present diffusely throughout the bipartite patella and on the far lateral aspect of the patella, at the fragment interface.

Attention was then turned to arthroscopic removal of the accessory patellar fragment (Figures 3A, 3B).

Figure 3.
An accessory superolateral arthroscopic portal was created to improve surgical instrument access. Round and oval burrs, straight and curved shavers, pituitary rongeur, curettes, and small osteotome were used to meticulously excise the accessory bipartite patella fragment, leaving the overlying (anterior) retinaculum intact. After the fragment was excised, the region was palpated, and no additional loose fragments were felt (Figures 4A, 4B).
Figure 4.
The remaining patellar articular cartilage was intact. On palpation, the patella did not sublux medially, indicating the lateral retinaculum was well maintained during excision of the patella fragment.

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