Bilateral sleeve fracture of the superior pole of the patella in a healthy adult: A case report

Abstract

BACKGROUND

Sleeve fracture of the patella is an unusual fracture, almost unique to children. The majority of sleeve fractures involve the inferior patellar pole. However, sleeve fractures of the superior pole of the patella are extremely rare in adults.

CASE SUMMARY

An 18-year-old male patient fell while running in the morning. The patient had tenderness to palpation at the superior pole of the patella, with a palpable gap over the upper part of the patella in both knees. We applied two 4.5-mm suture anchors with the Krackow stitch to repair the sleeve fracture, augmented by autogenous gracilis through performing the figure-of-eight technique. The patient regained approximately the full range of motion of the knee joint without any quadriceps weakness and a normal gait 6 weeks after surgery.

CONCLUSION

Sleeve fractures of the superior pole of the patella are extremely rare in adults, especially bilateral sleeve fractures. Suture anchors, augmented by autogenous gracilis, provided secure fixation and achieved excellent results in this rare injury.

Key Words: Sleeve fracture; Patella; Superior pole; Adult; Suture anchors; Case report

Core Tip: Sleeve fractures of the superior pole of the patella were rare in adults. We report an extremely rare case of an 18-year-old man with a bilateral sleeve fracture of the superior pole of the patella that occurred after a sudden fall while running. The patient’s physical examination, imaging examinations, and surgical procedure are presented, along with relevant images. Suture anchors, augmented by autogenous gracilis, provided secure fixation and achieved excellent results in this rare injury.

INTRODUCTION

Patellar fractures in children are rare, accounting for 1% of all fractures in children[1-6]. As a particular type of patellar fracture, sleeve fracture of the patella occurs when a “sleeve” of periosteum is torn off from the patella[5,7]. The sleeve fracture was first described by Houghton and Ackroyd in 1979, representing the most common type of patellar fracture in children[7-10]. The majority of sleeve fractures involve the inferior patellar pole[11-14], whereas fracture of the superior pole is a rare occurrence[5,15]. These fractures account for approximately half of all patellar fractures in children, and most cases are under the age of 16[6,10,16]. On reviewing the English literature, only seven cases were found in adults[5,15,17-21]. Compared to the immature pediatric skeleton, the enthesis of the adult patella is more resilient to avulsion injury, which may account for the low incidence in adults[15]. We report an extremely rare case of an 18-year-old man with a bilateral sleeve fracture of the superior pole of the patella that occurred after a sudden fall while running. To our knowledge, this is the first case of bilateral sleeve fracture of the superior pole of the patella in adults. The patient and his family were informed that data concerning the case would be submitted for publication, and they consented.

CASE PRESENTATION

Chief complaints

An 18-year-old Chinese man was admitted to the hospital on March 26, 2025, due to an injury sustained by falling while running in the morning.

History of present illness

The patient fell while running in the morning. The patient felt pain and swelling in both knee joints after both knees joints landed on the ground. The lower legs on both sides could not be raised independently.

History of past illness

There was no history of fracture or surgery.

Personal and family history

The patient had no significant past medical, surgical, or family history.

Physical examination

Mild joint effusion was present in both knees. The patient had tenderness to palpation at the superior pole of the patella, with a palpable gap over the upper part of the patella in both knees (Figure 1). He was unable to actively extend his knee in the sitting position and felt severe pain performing this action.

Figure 1 Preoperative physical examination showed a palpable gap over the upper part of the patella in both knees.

Laboratory examinations

No abnormalities were revealed by the laboratory examinations.

Imaging examinations

Magnetic resonance imaging (MRI) confirmed bilateral sleeve fracture of the superior pole of the patella (Figure 2).

Figure 2 Preoperative magnetic resonance imaging showed the bilateral sleeve fracture of the superior pole of the patella. A: Coronary magnetic resonance imaging (MRI) in the right knee; B: Sagittal MRI in the right knee; C: Coronary MRI in the left knee; D: Sagittal MRI in the left knee.

FINAL DIAGNOSIS

Based on the history, physical examination, and imaging examinations, the patient was diagnosed with bilateral sleeve fractures of the superior pole of the patella.

TREATMENT

The patient underwent open surgery for reconstruction of the knee extension apparatus 4 days after the trauma under general anesthesia through an anterior approach (Figure 3A). At surgery, a sleeve fracture of the superior pole of the patella was further confirmed, but there was no fragment of articular cartilage. There was a thin shell of bone avulsed from the proximal pole of the patella by the quadriceps tendon (Figure 3B and C). The quadriceps tendon with the patellar fracture piece was meticulously repaired and secured to the main patellar body by two 4.5-mm suture anchors with the Krackow stitch (Figure 3D). This repaired tendon was augmented with the autogenous gracilis by performing the figure-of-eight technique (Figure 3E).

Figure 3 Preoperative and intraoperative photos. A: Patient in the supine position with an anterior approach incision in both knees; B-E: Intraoperative photographs. A thin shell of avulsed bone in the right knee (B); A thin shell of avulsed bone in the left knee (C); Two 4.5-mm suture anchors placed on the upper part of the patella in the right knee (D); The autogenous gracilis was applied to augment the stability by performing the figure-of-eight technique in the right knee (E).

OUTCOME AND FOLLOW-UP

Postoperative plain radiography showed that the anterior tilt of the patella had been corrected, and the position of the suture anchors was good (Figure 4). Postoperatively, the knee was immobilized with an adjustable knee joint brace for 4 weeks. Six weeks after the surgery, the patient regained approximately a full range of motion of the knee joint, without any quadriceps weakness on clinical examination (Figure 5A and B). Meanwhile, the patient regained a normal gait (Figure 5C and D).

Figure 4 Plain radiography of bilateral knee joints after surgery. A: Anteroposterior radiography of bilateral knee joints; B: Lateral radiography of right knee joint; C: Lateral radiography of left knee joint.

Figure 5 Follow-up at 6 weeks after surgery. A and B: Range of motion of bilateral knee joints; C and D: Gait of the patient.

DISCUSSION

Sleeve fracture of the patella is an unusual type of fracture, almost unique to children[3,5,22,23]. The predominance of this injury in children may be due to their more flexible ligaments, hyaline cartilage, and joint capsule, resulting in greater joint laxity that protects the patella from trauma[5,22]. Therefore, avulsion fracture of the subchondral bone, or of the cartilage and retinaculum, is found more frequently than tendon rupture[2-4,6]. To our knowledge, only seven articles have reported specific cases of superior pole sleeve fractures of the patella in adults (Table 1). For the first time, we reported an extremely rare case of bilateral sleeve fracture of the superior pole of the patella in adults. We applied two 4.5-mm suture anchors with the Krackow stitch to repair the sleeve fracture, augmented by autogenous gracilis through performing the figure-of-eight technique. Our treatment provided secure fixation and excellent results in this rare injury.

Table 1 Summary of previous cases from review of English literature.

Ref.	Age	Gender	Mechanism	Treatment	Outcome (after surgery)
Xie et al[5], 2017	19	Female	Fall while jumping	Surgery	Full recovery at 6 months
Kushwaha et al[15], 2021	18	Male	Fall while trying to jump across a wall	Surgery	Full ROM at 10 weeks
Quraishi et al[17], 2021	23	Male	Fall from bike	Surgery	Full ROM at 4 months; return to sports activity at 16 months
Ro et al[18], 2014	24	Male	Forceful passive physiotherapy following cast immobilization	Surgery	Full ROM at 6 months; return to sports activity at 26 months
Teixeira et al[19], 2013	22	Male	Forceful kick to ball	Conservative	Full ROM and return to normal activity at 3 weeks
Hemeleers et al[20], 2018	19	Male	Fall on ground	Conservative	No follow-up
Kakazu et al[21], 2003	30	Male	Slip on ground	Surgery	Return to daily activity at 6 months

ROM: Range of motion.

Sleeve fractures of the patella usually occur in the inferior pole of the patella, and superior pole involvement is rare. There are different mechanisms underlying these two types of sleeve fractures. It is proposed that inferior pole sleeve fractures are due to rapid quadriceps muscle contraction, as occurs in jumping and skateboarding[15,18]. However, sleeve fracture of the superior pole occurs as a result of rapid quadriceps muscle contraction, with knee flexion that results in more force acting on the superior pole compared to the inferior pole. A plausible explanation for the fracture in the present case is that forced flexion while falling resulted in momentary tensile force at the quadriceps attachment site acting on the superior pole of the bilateral patella, similar to previous cases[15,18,19].

Sleeve fractures of the superior pole of the patella are extremely rare in adults and easy to neglect[15]. A plain radiograph may be misleading, and MRI remains the ideal imaging modality[17]. Based on the chief complaints and physical examination, we highly suspected rupture of the quadriceps tendon, which seemed to be confirmed by MRI. However, during the surgery, we found a thin shell of bone avulsed from the proximal pole of the patella by the quadriceps tendon. The patient was finally diagnosed with a bilateral sleeve fracture of the superior pole of the patella. Previous cases of sleeve fractures of the patella[5,17,19,24] presented the inability to raise the leg, consistent with the clinical manifestations in our case. Thus, sleeve fractures of the patella should be considered when patients have limited mobility.

Treatment options include conservative and operative management, according to the displacement and size of the fragment. In two adult cases, conservative treatment was chosen for the fractures as the displacement was not greater than 2 mm[19,20]. Conservative management is mainly applicable to minimally displaced fractures and may cause retraction of the quadriceps muscle as well as joint stiffness. Furthermore, the avulsed sleeve tissue in our patient had osteogenic tissue due to the periosteal sleeve being attached to the fracture fragment. Missed diagnosis or a delay in treatment may cause new bone formation and permanent disability[15]. Therefore, surgical management for this type of fracture is the preferred treatment. At present, there is no standard treatment for a sleeve fracture of the superior pole of the patella. Strong and secure fixation is crucial for rapid postoperative recovery. The use of the figure-of-eight technique for autologous graft augmentation is reliable for early postoperative rehabilitation, without interfering with the healing of sleeve fractures. Our case regained approximately the full range of motion of the knee joint and a normal gait 6 weeks after the surgery, showing faster recovery than other adult cases undergoing surgery[5,15,17,18,21].

Although the injury mechanism is similar, quadriceps tendon rupture needs to be distinguished from sleeve fractures of the superior pole of the patella. Quadriceps tendon ruptures in the native knee are relatively rare and require a pathologic tendon[25,26]. Most patients who suffer quadriceps ruptures have underlying disease[27], including diabetes, thyroid disease, renal disease, etc. The laboratory examinations were normal in our patient. Furthermore, the site of quadriceps tendon rupture is in the tendon section, while the site of sleeve fractures of the superior pole is the junction of the tendon and bone. There is a particularly high male predominance of sleeve fracture of the superior pole in adults, with six male and one female case being reported[5,15,17-21]. Our case also occurred in a male patient. The reasons for the gender differences in this disease need further clarification.

CONCLUSION

Sleeve fractures of the superior pole of the patella are extremely rare in adults. For the first time, we present a bilateral sleeve fracture in an 18-year-old man. A palpable gap over the upper part of the patella should be considered in this type of fracture and verified by MRI. Suture anchors, augmented by autogenous gracilis, provided secure fixation and achieved excellent results in this rare injury.