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Clinical History

The patient was hit by a car in a road traffic accident. Following the accident he complained of pain in his left knee. On examination the left knee was tender and swollen with a tense haemarthrosis.

Imaging Findings

The patient was hit by a car in a road traffic accident. Following the accident he complained of pain in his left knee. Further evaluation revealed no other injuries of the head, chest, abdomen or skeleton. On examination the left knee was tender and swollen with a tense haemarthrosis. There was no distal neurovascular deficit. Plain anteroposterior radiographs revealed what appeared to be a straightforward Salter Harris IV fracture of the distal femur (Figs 1a and 1b), but at open surgery the fracture pattern was a combination of Salter Harris II & III types. The epiphysis had fractured at the intercondylar notch and the lateral portion had displaced and angulated anteriorly as the Salter Harris III component. The adjacent fragment of metaphysis, instead of remaining attached to the epiphysis as in a Salter Harris IV pattern, had been fractured from the epiphyseal fragment through the growth plate and was lying laterally as a seperated Thurston Holland fragment. This biplanar pattern of distal femoral fracture is very rare and to our knowledge, has never been previously described. Both fragments had to be separatly fixed (Figs 2a and 2b).

Discussion

Distal femoral epiphyseal fractures have a high incidence of physeal growth disturbance, which can result in asymmetry of length, angulation or both. Growth disturbance is caused by bony bridging, which results from direct physeal trauma or from lack of anatomic reduction of the physis. Distal femoral physeal injuries account for approximately five percent of all physeal injuries and less than one percent of all fractures in children.

The Salter Harris II pattern, characterised by an oblique extension of the fracture across one corner of the adjacent metaphysis, is the most common type of separation at the distal femur and usually occurs in adolescents. Displacement is usually towards the side of the metaphyseal fragment (Figs 1a and 1b). If asymmetric growth follows a type II separation, the portion of the physis underneath the metaphyseal fragment is spared. Therefore, if the metaphyseal injury is medial, deformity is more likely to be valgus than varus. If the metaphyseal fracture is lateral, varus angulation is more likely.

A Salter Harris type III injury consists of a partial separation of the physis, with a vertical fracture line extending from the physis down to the articular surface of the epiphysis (Figs 1a and 1b). The fracture is usually close to the intercondylar notch and involves the medial condyle and is often associated with cruciate ligament damage.

A Salter Harris IV injury is a vertical fracture extending from the metaphyseal cortex across the physis and entering the articular surface of the epiphysis.

Whenever possible, fixation devices are placed to avoid crossing the physis to avoid further physeal injury. In Salter Harris III separations, screws/pins may be placed transversely through the epiphysis. In Salter Harris II and IV separations, screws/pins are placed transversely through the metaphysis (Fig 2a and 2b). Thus this case shows the imperfections of the Salter-Harris classification and the limitations of conventional radiography.The use of CT and MRI increases the accuracy of diagnosis but in the ideal world it cannot be used in all trauma cases.

Differential Diagnosis List

Distal femoral epiphyseal injury: biplanar injury

Final Diagnosis

Distal femoral epiphyseal injury: biplanar injury

Liscense

Figures

Anteroposterior and lateral radiographs of the distal femur

Postoperative anteroposterior and lateral radiographs of the distal femur

Imaging Findings

Based on the provided X-rays (preoperative and postoperative), a fracture line is visible at the left distal femoral epiphysis (the distal femoral growth plate region), primarily along the physis and extending toward the adjacent diaphysis. The preoperative film shows poor alignment of the fracture ends, accompanied by significant soft tissue swelling, suggesting possible hemarthrosis (tense joint effusion). The postoperative film shows two screws placed horizontally, fixing both the femoral diaphysis and epiphysis, resulting in good fracture alignment and stability. Overall, the fracture line is located at the physis and extends into part of the proximal diaphysis, consistent with features of a Salter-Harris Type II fracture.

Potential Diagnoses

Salter-Harris Type II Distal Femoral Fracture: This type is most common in adolescents, with a fracture line at the physis and often a small or large bony fragment on the diaphyseal side (a “wedge” or “corner” fragment). The clinical and imaging features are consistent with this case. Fixation typically needs to include the diaphysis to prevent further physeal damage.
Salter-Harris Type III or IV Fractures: These should be considered if the fracture line extends into the articular surface (Type III) or traverses from the diaphysis through the physis into the joint (Type IV). However, based on the images, Type II is more likely, and the postoperative fixation method here also aligns more with the standard lateral fixation approach for Type II or IV. Type III or IV fractures often involve more pronounced articular surface injury, which may be noted on imaging as clear articular separation or collapse.

Taking into account the patient’s age (14 years), mechanism of injury (collision in a car accident), and imaging findings, Salter-Harris Type II is especially common and most fitting for this case.

Final Diagnosis

Considering the patient’s mechanism of injury, age, symptoms, and radiographic findings, the most likely diagnosis is:

Left Distal Femoral Salter-Harris Type II Fracture.

If there are still uncertainties in the imaging or if further evaluation of cartilage and articular surface damage is needed, an MRI may be considered to identify any occult fracture lines or cartilage injuries.

Treatment Plan and Rehabilitation Program

Treatment Strategy:

The imaging reveals that surgical internal fixation has been performed with screws placed horizontally, which is a common and effective intervention to stabilize the fracture and reduce the risk of further physeal damage.
Postoperative follow-up is recommended to monitor fracture healing and growth plate function, being vigilant about early physeal closure or later abnormalities in knee alignment.
In cases without surgical indications or when the fracture is stable, cast or brace immobilization can be considered. However, in the presence of significant displacement or instability in a distal femoral physeal fracture, prompt surgical intervention is often required.

Rehabilitation and Exercise Prescription Recommendations (FITT-VP Principle):

Early Phase (0–6 weeks after surgery):
- Frequency: Perform simple joint range-of-motion exercises 2–3 times daily (under the guidance of a physician or physical therapist).
- Intensity: Primarily low-intensity, with no or partial weight-bearing. Avoid vigorous activities or excessive joint loading.
- Time: Each session can last 5–10 minutes, featuring gentle active or passive joint movement to reduce swelling and maintain flexibility.
- Type: Passive joint mobilization, gliding exercises, or isometric training within the limits of the fixation device.
- Progression: Assess range of motion and weight-bearing capacity weekly or biweekly based on fracture healing; do not increase load prematurely.
Intermediate Phase (6–12 weeks after surgery):
- Gradually adjust weight-bearing as the fracture heals, and begin light to moderate strength exercises such as straight-leg raises, lower limb strengthening, and coordination drills.
- Consider aquatic therapy if available, utilizing water’s buoyancy to reduce joint stress.
Late Phase (3 months and onward):
- Once imaging confirms solid fracture healing, gradually resume activities like running and jumping. Start with walking or slow jogging to avoid abrupt impact.
- Increase exercise intensity progressively based on professional evaluation, ensuring knee joint stability before returning to regular adolescent sports activities.
- Continue follow-up to monitor lower limb alignment (particularly varus or valgus deformities) and compare leg length on both sides.

Throughout rehabilitation, closely monitor pain, swelling, and functional improvements. If significant pain worsens, joint instability occurs, or deformity progresses, revisit clinical evaluation and adjust the program promptly.

Disclaimer: This report serves only as a reference for medical analysis and cannot replace in-person consultation or professional medical advice. Please follow the assessment and recommendations of your clinical specialist for actual diagnosis and treatment.

Human Doctor Final Diagnosis

Distal femoral epiphyseal injury: biplanar injury

AI Doctor