# Clinical Cases: Lower Limb - Hip and Thigh

## Case 1: Femoral Neck Fracture in the Elderly

### Clinical Image
![Femoral Neck Fracture](case_01_image.jpg)
*Source: [Wikimedia Commons - Garden Classification](https://commons.wikimedia.org/wiki/File:Garden_classification.jpg) - CC BY-SA 3.0*

### Case Presentation
An 82-year-old woman with a history of osteoporosis and dementia is brought to the emergency department from her nursing home after being found on the floor beside her bed. Staff heard a loud noise and found her unable to stand. She is confused at baseline and cannot provide a clear history, but points to her right hip when asked about pain. Physical examination reveals the right lower extremity is shortened and externally rotated compared to the left. There is significant tenderness over the right groin and hip. Attempted range of motion of the hip elicits severe pain. She is unable to perform a straight leg raise on the right side. Neurovascular examination reveals intact distal pulses and sensation. Radiographs demonstrate a displaced subcapital femoral neck fracture (Garden type IV). Laboratory studies show mild anemia and normal renal function. Given the displacement and patient's age, she is taken to the operating room the following day for hemiarthroplasty (replacement of the femoral head with preservation of the native acetabulum). She is mobilized on postoperative day one and discharged to rehabilitation on day three.

### Key Learning Points
- The femoral neck is intracapsular; fractures disrupt the retinacular vessels that supply the femoral head
- The medial femoral circumflex artery provides the primary blood supply to the femoral head via retinacular branches
- Displaced femoral neck fractures have high rates of avascular necrosis and nonunion in elderly patients
- Classic presentation: shortened, externally rotated leg due to unopposed action of iliopsoas and external rotators
- Garden classification grades fracture displacement: Types I/II (nondisplaced) often treated with fixation; Types III/IV (displaced) treated with arthroplasty in elderly

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## Case 2: Posterior Hip Dislocation

### Clinical Image
![Posterior Hip Dislocation](case_02_image.jpg)
*Source: [Wikimedia Commons - Hip Dislocation](https://commons.wikimedia.org/wiki/File:Hip_dislocation.jpg) - CC BY-SA 3.0*

### Case Presentation
A 28-year-old unrestrained driver is brought to the trauma center after a head-on motor vehicle collision. He reports his knee struck the dashboard upon impact. He complains of severe left hip pain and cannot move his left leg. Primary survey is unremarkable except for the obvious left lower extremity deformity. Secondary survey reveals the left leg is shortened, adducted, internally rotated, and flexed at the hip - the classic position of posterior hip dislocation. There is no open wound. Neurovascular examination reveals diminished sensation over the dorsum of the left foot, and he is unable to dorsiflex his ankle (foot drop). Palpable dorsalis pedis and posterior tibial pulses are present. AP pelvis radiograph confirms posterior dislocation of the left femoral head without visible acetabular fracture. The hip is reduced emergently in the trauma bay using the Allis maneuver with the patient under procedural sedation. Post-reduction examination shows improvement in sciatic nerve function with return of ankle dorsiflexion. CT scan confirms concentric reduction and reveals a small posterior wall acetabular fracture. He is kept non-weight-bearing and managed conservatively.

### Key Learning Points
- Posterior hip dislocations account for 90% of traumatic hip dislocations, typically from dashboard injury
- The sciatic nerve courses posterior to the hip joint and is injured in 10-20% of posterior dislocations
- Classic presentation: shortened, adducted, internally rotated, and flexed hip
- The posterior capsule and posterior acetabular rim are weaker than the anterior structures
- Time to reduction is critical; rates of avascular necrosis and sciatic nerve injury increase after 6 hours

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## Case 3: Trendelenburg Gait from Superior Gluteal Nerve Injury

### Clinical Image
![Trendelenburg Sign](case_03_image.jpg)
*Source: [Wikimedia Commons - Trendelenburg Sign](https://commons.wikimedia.org/wiki/File:Trendelenburg_sign.png) - CC BY-SA 4.0*

### Case Presentation
A 55-year-old woman presents to orthopedic clinic 3 months after undergoing right total hip arthroplasty for osteoarthritis via a direct lateral approach. While her pain has improved significantly, she has noticed a limp and weakness when climbing stairs. She reports that her pelvis "drops" to the left when she stands on her right leg. Physical examination reveals antalgic gait with the pelvis dropping toward the unsupported (left) side during the stance phase of the right leg - a positive Trendelenburg sign. She compensates by leaning her trunk over the affected hip (abductor lurch). Manual muscle testing demonstrates 3/5 strength of right hip abduction (gluteus medius and minimus) compared to 5/5 on the left. Hip flexion, extension, and rotation strength are normal. There is no pain with range of motion, and the surgical incision is well-healed. Radiographs show a well-positioned prosthesis. EMG confirms denervation of the gluteus medius consistent with superior gluteal nerve injury. She is referred for physical therapy with abductor strengthening exercises. At 9-month follow-up, she has improved to 4/5 hip abduction strength with improving gait.

### Key Learning Points
- The superior gluteal nerve (L4-S1) innervates gluteus medius, gluteus minimus, and tensor fasciae latae
- The nerve exits the pelvis above the piriformis muscle and courses between gluteus medius and minimus
- Superior gluteal nerve injury causes weakness of hip abduction and positive Trendelenburg sign
- During single-leg stance, hip abductors stabilize the pelvis; weakness causes the contralateral pelvis to drop
- Lateral surgical approaches to the hip place the superior gluteal nerve at risk