Patellar incarceration with rotational dislocation in a medial femoral condyle fracture: A case report

INTRODUCTION

Knee injuries, particularly those involving fractures and dislocations, significantly contribute to morbidity, especially among elderly patients. These complex injuries often require a comprehensive approach to both diagnosis and management. Patellar dislocations, although relatively common, can sometimes present with unusual complications, such as incarceration within fracture sites, which complicates both diagnosis and treatment.^[1]

This case report details the rare presentation of a 70-year-old female with a partial articular fracture of the medial femoral condyle and an incarcerated patellar dislocation. It highlights the challenges and considerations involved in managing such complex injuries. The patient, with a history of hypertension (HTN) and type 2 diabetes mellitus (T2DM), presented with severe knee pain and swelling following a fall. Initial radiographs and subsequent computer tomography (CT) scans confirmed the diagnosis, showing the patella rotated along its longitudinal axis and incarcerated within the fracture site.

This unusual presentation required open reduction and internal fixation (ORIF), emphasizing the importance of careful surgical planning and execution.^[2] The case highlights the importance of thorough clinical and radiological evaluation in elderly patients with knee injuries. It also illustrates the potential complications and post-operative challenges, such as seizures and hyperglycemia, that may arise in patients with comorbidities. Successful management of this case through ORIF and subsequent medical treatment provides insights into the multidisciplinary approach required for such complex presentations. Clinically, certain presenting features may alert the clinician to this rare injury pattern. Severe knee pain, immediate swelling, inability to bear weight, and a knee locked in extension following trauma should raise suspicion for a complex extensor mechanism injury. The presence of a palpable anterior knee defect or gross deformity may indicate rotational patellar dislocation with incarceration into an associated fracture site. Recognition of these symptoms should prompt urgent radiographic and computed tomography evaluation to identify patellar rotation and fracture entrapment, facilitating early surgical intervention.

CASE REPORT

A 70-year-old female with a history of HTN and T2DM presented to the emergency department after falling down a flight of steps. She reported severe pain and swelling in her left knee, along with an inability to bend or bear weight on the affected limb. On physical examination, the patient’s left knee was locked in extension, with significant swelling. While no external wounds were visible, a palpable gap was noted over the anterior aspect of the knee, which was extremely tender. The limb’s neurovascular status remained intact.

Plain radiographs revealed a partial articular fracture of the medial femoral condyle along with patellar dislocation. The patella was notably rotated along its longitudinal axis and incarcerated within the fracture site. A CT scan was performed to better assess the fracture configuration, which confirmed the diagnosis [Figure 1].

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Figure 1:

(a) Preoperative anteroposterior radiograph demonstrating partial articular fracture of the medial femoral condyle with abnormal patellar alignment. (b) Preoperative lateral radiograph showing rotational displacement of the patella with incarceration. (c) Postoperative anteroposterior radiograph demonstrating anatomical reduction and fixation using tension-band wiring. (d) Postoperative lateral radiograph confirming restoration of patellar alignment and stable fixation construct.

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A standard midline anterior knee incision was made. Intraoperatively, the patella was found to be rotated along its longitudinal axis and incarcerated between the fractured medial femoral condyle fragments, with partial tearing of the quadriceps and patellar tendons. Gentle derotation of the patella was performed, followed by careful disengagement of the incarcerated extensor mechanism. The knee joint was irrigated with normal saline, and the fracture margins were debrided. The medial femoral condyle fracture was anatomically reduced and temporarily stabilized. The patellar fracture was reduced and fixed using two parallel 1.6-mm Kirschner wires placed longitudinally, followed by application of a 1.2-mm stainless steel tension-band wire in a figure-of-eight configuration close to the articular surface. The Kirschner wires were bent proximally and impacted distally to prevent migration. The quadriceps tendon, patellar tendon, and medial and lateral retinacula were repaired using interrupted non-absorbable sutures. Intraoperative fluoroscopy confirmed satisfactory reduction, restoration of articular congruity, and stable fixation of the patellar construct [Figure 1]. The wound was closed in layers, and an above-knee posterior slab was applied. During surgery, the patient received intravenous ceftriaxone (1 g), tramadol hydrochloride (100 mg), and bupivacaine hydrochloride (0.5%).

Postoperatively, the patient was allowed to bear weight as tolerated and received 24 h of intravenous antibiotics before being discharged the following day. However, a few days later, the patient developed seizures and was readmitted. On examination, her blood pressure was elevated, likely secondary to breathlessness. Initial investigations revealed hyperglycemia and HTN [Table 1]. She was treated with intravenous mannitol (500 mL), ceftriaxone (2 g twice daily), pantoprazole (40 mg), and levetiracetam (1 g) to control the seizures. After regaining consciousness, her condition stabilized. The patient’s intravenous fluids included normal saline (100 mL) and half a bottle of dextrose and sodium chloride at a rate of 50 mL/h (200 mL/day for 3 days). The ceftriaxone dose was later adjusted to 1.5 g twice daily, and ondansetron (2 mg/mL) was administered twice daily for 3 days.

A brain CT scan revealed a small hypodense area in the left occipito-temporal lobe, consistent with an acute infarct [Figure 2]. The patient’s condition remained stable, and she is currently under regular follow-up to monitor her recovery.

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Figure 2:

Non-contrast computed tomography scan of the brain showing a small hypodense area in the left occipitotemporal region consistent with acute infarct.

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DISCUSSION

The patella, the largest sesamoid bone in the human body, plays a crucial role in the extensor apparatus. Patellar fractures account for approximately 1% of all fractures seen in emergency departments, with only about one-third requiring surgical intervention.^[3] In this case, the partial articular fracture involved only a portion of the articular surface, which forms a joint with another bone.^[4]

Patellar fixation is a surgical procedure aimed at stabilizing the patella in its natural position, addressing conditions such as subluxation, dislocation, and instability.^[4] In this patient, despite the absence of an external wound, a palpable gap was noted over the anterior aspect of the knee. Surgical intervention is typically indicated in cases of diastasis or fragment separation greater than 3 mm, displacement or articular step-off exceeding 2 mm, osteochondral fractures with intra-articular loose bodies, or a compromised extensor mechanism.^[5]

Surgical procedures, including patellar fixation, carry risks of complications, such as infection, delayed wound healing, discomfort, or wire breakage.^[6,7] In this case, the radiolucency of cartilage made precise visualization difficult during surgery. Patellar fractures represent roughly 1% of all skeletal injuries.^[8] A Swedish study reported an incidence of 13.1/100,000 person-years, with increasing rates among older adults. The median age of patients with patellar fractures is 67 years, and women account for 64% of cases, with women being 1.5 times more likely than men to sustain such fractures. Low-energy trauma, mainly from falls, is the leading cause, with over 70% of fractures resulting from falls from standing height.^[9,10]

In this case, the 70-year-old female patient, with a history of HTN and T2DM, sustained a dislocated patella and a partial articular fracture of the medial femoral condyle following a fall. ORIF was performed as the standard treatment for displaced patellar fractures. However, post-operative complications included seizures and hyperglycemia, with a subsequent brain CT scan revealing a small hypodense area consistent with an acute infarct.

CONCLUSION

This case highlights the complexity of managing a partial articular fracture of the medial femoral condyle with patellar dislocation in an elderly patient with multiple comorbidities. The successful ORIF underscores the importance of precise surgical techniques in achieving favorable outcomes. However, post-operative complications, including seizures and an acute infarct, emphasize the need for vigilant postoperative monitoring, especially in patients with underlying conditions such as HTN and diabetes. This case also demonstrates the critical role of multidisciplinary care in addressing both orthopedic and medical complications, ensuring comprehensive recovery. Regular follow-up is essential to monitor progress and manage any long-term sequelae.