Floating patella: Ipsilateral and simultaneous rupture of the quadriceps and patellar tendons in a young individual (a surgical case report)

Abstract

Introduction and importance

The phenomenon of a floating patella or ipsilateral bifocal rupture of the extensor apparatus is an extremely rare injury, with few cases reported in the literature. The aim of this case study is to report an unprecedented event: the simultaneous trans-tendinous rupture of both quadriceps and patellar tendons in a young adult without predisposing factors, emphasizing the need for awareness in diagnosis and management, and suggesting a new avenue for research in prevention and rehabilitation.

Case presentation

We report the case of a 35-year-old patient with no significant medical history, who experienced this injury following a sudden start in a sprint without prior warm-up. The clinical examination revealed a swollen, painful knee with active extension deficit, patellar ascent, and a sub patellar hiatus. Magnetic Resonance Imaging (MRI) confirmed a trans-tendinous rupture of both the patellar and quadriceps tendons.

Clinical discussion

Tendon repair was performed using end-to-end sutures and a figure-8 reinforcement with the semitendinosus tendon, along with gracilis plastie to strengthen the patellar tendon repair. This methodological approach is discussed in the context of its effectiveness and potential implications for future surgical management of similar injuries.

Conclusion

After a 12-month follow-up, the patient exhibited highly satisfactory results, resuming both professional and sporting activities. To our knowledge, this is the first published case of a trans-tendinous rupture of the extensor apparatus tendons. This observation serves as a reference in understanding the mechanism and surgical management of such lesions, emphasizing the need for further research and clinical vigilance in similar cases.

Highlights

• •Rarity of Injury: The article documents an extremely rare orthopedic injury involving a simultaneous trans-tendinous rupture of both the quadriceps and patellar tendons in a young adult, emphasizing the uniqueness of the case.
• •Importance of Diagnosis and Management: It underscores the critical need for prompt and accurate diagnosis using MRI, followed by a tailored surgical approach, highlighting the importance of adept management in such complex injuries.
• •Surgical Intervention Success: Demonstrates the effectiveness of current surgical techniques, including end-to-end sutures and figure-8 reinforcement with tendon grafts, followed by structured rehabilitation, in achieving optimal recovery outcomes.
• •Potential for Full Recovery: Highlights the patient's successful return to professional and sporting activities post-recovery, showcasing the potential for full rehabilitation from significant knee injuries with appropriate care.
• •Call for Further Research: Suggests new avenues for research into the prevention, diagnosis, and management of similar rare tendon injuries, advocating for clinical vigilance and further studies to improve patient outcomes.

1. Introduction

The rupture of any component of the knee's extensor apparatus often leads to an active extension deficit of the knee, which can have severely disabling functional consequences. This necessitates early surgical intervention, particularly when there's an active extension deficit. Such injuries, especially to the patellar and quadriceps tendons, are infrequent [1,2]. However, the simultaneous bifocal rupture of the extensor apparatus, termed ‘floating patella’, first described by Huber et al. [4] and later classified into five types by Kang et al. [5], remains an exceedingly rare lesion with few reported cases in the literature. To our knowledge, this report presents the first case of a subcutaneous and simultaneous rupture of both the quadriceps and patellar tendons without osseous lesions in a healthy young individual (without underlying tendinopathy).

2. Methods

This case report outlines the assessment, diagnosis, and surgical management of a young adult patient who experienced a simultaneous and trans-tendinous rupture of both the quadriceps and patellar tendons, a particularly rare orthopedic injury. The patient was treated in a facility specializing in orthopedic and sports-related injuries.

All medical procedures, including imaging, surgical intervention, and rehabilitation, were conducted in accordance with established protocols at this specialized center. The case report was meticulously documented, and its presentation adheres to the SCARE 2023 guidelines: updating consensus Surgical Case Report (SCARE) guidelines [17], which set the standards for high-quality reporting in surgical case reports.

3. Case presentation

We report the case of a 35-year-old, occasionally active, overweight male patient (BMI: Body Mass Index of 29 kg/m²) with no notable pathological history, no history of medication intake such as fluoroquinolones or corticosteroids, and no prior knee pain. The patient experienced an immediate instability in his right knee with a sensation of cracking, pain, and total functional impairment following a sports accident without prior warm-up. The incident occurred during a sprint start with the right lower limb bearing weight, knee bent, and foot anchored to the ground, leading to an immediate cessation of his sports activity.

A comparative clinical examination of both knees revealed a swollen, painful right knee without notable skin lesions, an absolute deficit in active extension, and a positive patellar tap test, a 1 cm patellar ascent, and a sub patellar hiatus (Fig. 1).

Fig. 1.

Clinical appearance demonstrating an elevation of the right patella compared to the left side.

Given these clinical findings, damage to the right knee's extensor apparatus was evident. Standard knee radiography showed a patella alta without fractures or avulsion, and no tendinous calcification or ossification. Knee ultrasound indicated an almost total rupture of the quadriceps tendon and a total rupture of the patellar tendon, along with moderate joint effusion. To complete the injury assessment, a knee MRI was performed, revealing an almost total rupture of the quadriceps tendon about 14 mm from its distal insertion and a total rupture of the patellar tendon approximately 10 mm from its distal insertion, without associated ligament or meniscal injuries and no signs of chronic tendinopathy (Fig. 2).

Fig. 2.

MRI appearance of the rupture of both tendons of the extensor apparatus.

The patient underwent surgery, with the knee flexed at 45° and without a pneumatic tourniquet. The procedure began with the harvesting of the semitendinosus and semimembranosus tendons. A median approach exploration revealed a rupture of the quadriceps tendon 15 mm from its patellar insertion and a patellar tendon rupture 1 cm from its proximal insertion without rupture of the patellar wings. The quadriceps tendon was repaired with direct non absorbable suture, and a figure-8 reinforcement with the semitendinosus tendon after drilling two transverse tunnels through the patella and tibial tuberosity. Subsequently, the patellar tendon was repaired using end-to-end sutures using non-absorbable thread and reinforced with a gracilis plastie (Fig. 3).

Fig. 3.

Drilling of the sub-tuberosity and trans-patellar tunnels, and the figure-eight reinforcement with the semitendinosus, including the end-to-end suture of the quadriceps tendon.

Postoperative recovery was uneventful. The patient began passive rehabilitation the day after surgery using a motorized orthosis at a rhythm of 0 to 45° for the first 15 days, then 0–70° for the following 15 days, and 0–90° for the remaining days, with weight-bearing on a rigid extension splint throughout this period. Subsequently, the patient started eccentric and concentric quadriceps exercises and resumed running at 7 months. At a 12-month follow-up, the patient demonstrated a mobility range of 0–135°, with quadriceps and hamstring muscle strength rated at 5 and equal to the contralateral side (Fig. 4). He reported no pain during daily activities, including carrying heavy loads, and was very satisfied with the functional outcome, scoring 99 on the Lysholm scale and 96.6 on the IKDC: International Knee Documentation Committee score.

Fig. 4.

Patient after a 12-month follow-up.

4. Discussion

In the traumatic pathology of the knee's extensor apparatus, patellar fractures are the most common, followed by ruptures of the patellar and then the quadriceps tendons [6]. Quadriceps tendon ruptures are typically seen after the age of 40, often occurring during a hyperflexion trauma with violent quadriceps contraction to prevent a fall [3]. Conversely, patellar tendon ruptures affect active individuals under 40 years of age, following indirect trauma due to abrupt quadriceps contraction on a slightly flexed knee, such as during a jump, sprint, or avoiding a fall [7], or due to a direct blow to the sub-patellar region on a knee flexed at 90 degrees [8]. These ruptures are almost always complete, occurring at the tip of the patella or in the sub-patellar region in two-thirds of cases, and more rarely in the tendon itself or at the insertion of the anterior tibial tuberosity [9]. Such tendon ruptures often occur in tendons weakened by repeated micro trauma in athletes [10], systemic diseases, long-term corticosteroid or fluoroquinolone use [11], and after local corticosteroid injections.

Bilateral ruptures of the quadriceps or patellar tendons are not uncommon, with several cases reported in the literature [2,12,13]. In Vidil et al.'s series [3], bilateral quadriceps tendon rupture accounted for 12 %. The simultaneous bifocal rupture of the extensor apparatus, termed ‘floating patella’, is extremely rare. The first case was reported by Goodier et al. [14], but Huber et al. [4] were the first to use the term ‘floating patella’ to describe this type of lesion. Kang et al. [5] classified the bifocal rupture of the extensor apparatus into five types:

• •Type 1 involves a fracture-avulsion of the tibial tuberosity with avulsion of the patellar tendon from its tuberosity insertion;
• •Type 2 is a fracture-avulsion of the lower pole of the patella with avulsion of the patellar tendon from the tibial tuberosity;
• •Type 3 is a fracture-avulsion of the tibial tuberosity with a quadriceps tendon rupture;
• •Type 4 is a fracture-avulsion of the tibial tuberosity with a fracture-avulsion of the lower pole of the patella
• •Type 5 is a quadriceps tendon rupture associated with an avulsion of the patellar tendon from the patellar tip.

In our case report, the lesion did not fit any of these classifications, with trans-tendinous ruptures occurring indirectly during a sprint involving sudden eccentric quadriceps contraction while the foot was planted and the knee flexed in an occasionally active, overweight young individual. The MRI showed no signs of secondary ruptures.

To our knowledge, this is the first report of a simultaneous subcutaneous rupture of both the quadriceps and patellar tendons without osseous lesions in a healthy young individual (without underlying pathology or tendinopathy). Chappius et al. [15] reported a simultaneous quadriceps tendon rupture in a 72-year-old patient following a fall without direct trauma, while Langer et al. [16] reported another case in a 37-year-old professional basketball player with a history of partial patellar tendon repair at age 9, renal transplantation, and long-term corticosteroid treatment for segmental and focal glomerulosclerosis.

The treatment of recent and total ruptures of any of the knee extensor apparatus tendons is always surgical, regardless of the patient's age and physical activity. The techniques are well-codified, largely depending on the level of rupture and the local state of the tendon, and generally yield good results [2]. In our case, in the absence of consensus and similar cases in the literature, we opted for end-to-end tendon repair, figure-8 reinforcement with the semitendinosus, and reinforcement of the patellar tendon repair with gracilis plastie to enable early rehabilitation. The outcome was very satisfactory; after a 12-month follow-up, the patient resumed his sports and professional activities.

5. Conclusion

To our knowledge, this is the first reported case of a simultaneous and trans-tendinous rupture of both the quadriceps and patellar tendons in a young adult without any predisposing factors. This observation not only could serve as a reference for understanding the mechanism but also underscores the importance of considering such rare possibilities in differential diagnosis. It highlights the need for prompt and accurate imaging, followed by an individualized surgical approach. Furthermore, this case suggests a potential area for further research, particularly in exploring preventive strategies and optimizing rehabilitation protocols for such unusual injuries. These insights could significantly contribute to the surgical management and postoperative care of similar lesions in the future.

Consent

Written informed consent was obtained from the patient for publication of this case report and accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal on request.

Provenance and peer review

Not commissioned, externally peer reviewed.

Ethical approval

This case report is exempt from ethical approval at our institution.

Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Guarantor

The grantors for this case series are the first author doctor Omar Chraibi and the corresponding author doctor Lamris Mohamed Amine.

CRediT authorship contribution statement

All authors have contributed equally to all parts of the elaboration of this case series.

Declaration of competing interest

The authors report no declarations of interest.