When evaluating a possible hip dislocation, it is important to note that hip dislocations are almost always associated with other injuries…

Case

A 33-year-old previously healthy male presented to the ED with right hip pain after an MVC in which he was the unrestrained passenger in a car going 30-40 MPH. Vitals were notable for HR of 105, and were otherwise within normal limits. On physical exam, his right lower extremity was without obvious deformity or overlying skin changes, but was noted to be shortened with tenderness to palpation and pain with range of motion about the hip. The leg was neurovascularly intact. The following radiographs were obtained:

diagnosis

Posterior hip dislocation with associated comminuted acetabular fracture

discussion

Hip dislocations are traumatic injuries in which the femoral head dislocates from the acetabular socket. Native hip dislocations most commonly occur in young patients with high energy mechanisms (such as high speed MVCs). Prosthetic hip dislocations can occur with low-energy trauma. Dislocations can be simple (no associated fracture) or complex (with an associated acetabular or proximal femur fracture). Patients will typically report acute pain and inability to bear weight.

Hip dislocations are anatomically classified as posterior or anterior:

Posterior hip dislocations: These comprise 90% of hip dislocations and occur when an axial load is placed on the femur while the hip is flexed and adducted (such as with a dashboard injury). They will present with the hip and leg in slight flexion, adduction, and internal rotation. These are associated with posterior wall acetabular fractures, femoral head fractures, ipsilateral knee injuries, osteonecrosis, and sciatic nerve injury (~10%1).

Anterior hip dislocations: These comprise only 10% of hip dislocations [2] and occur when an axial load is placed on the femur while the hip is abducted and externally rotated. They will present with the hip and leg in extension, abduction, and external rotation. These are associated with chondral injury or femoral head impaction; there is rarely neurovascular compromise.

When evaluating a possible hip dislocation, it is important to note that hip dislocations are almost always associated with other injuries (in 95% of cases), including a reported 8% incidence of co-occurring thoracic aortic injuries. [3]

If concerned for a hip dislocation, AP and cross-table lateral radiographs (to differentiate between anterior and posterior dislocation and to evaluate for femoral fractures) should be obtained. After reduction, AP, inlet/outlet, and judet views should be obtained. CT should be considered to evaluate the acetabulum for small fractures. Knee radiographs should also be considered due to frequent co-occurrence (~25%) of hip dislocations and knee injuries. [4]

Native hip dislocations (as opposed to hip prosthetic dislocations) should be reduced within 6 hours due to risk of avascular necrosis. [5] The incidence of avascular necrosis after traumatic hip dislocation (1.7-40%) can be minimized to 0-10% if reduced within 6 hours. [6] Hip prosthetic dislocations are less emergent. Femoral neck fractures are a contraindication to a closed reduction. Post-reduced radiographs should be obtained to ensure concentric reduction. A CT is often obtained after reduction to rule out femoral head fractures, as well as intra-articular loose bodies and incarcerated fragments.

Posterior hip reduction techniques:

Allis Maneuver [7]: One provider applies distal traction to the flexed knee while another provider provides counter traction by applying downward pressure on the pelvis.

Waddell Technique [8]: Provider squats on stretcher and places forearm under patient’s knee; provider’s forearm rests on own knees. Provider then leans back while another provider is applying counter traction via downward pressure to the pelvis.

Captain Morgan Hip Reduction [9]: Provider stands by stretcher and places own knee behind patient’s flexed knee. Provider plantar flexes own foot to provide anterior force.

Anterior hip dislocations can be reduced with traction and internal rotation, followed by external rotation.

After a successful reduction, precautions must be taken to prevent re-dislocation. Weight bearing status should be toe touch. Avoid hip flexion past 90 degrees (apply a knee immobilizer as most patients cannot significantly flex hip without flexing knee).

In the case of a simple hip dislocation with successful reduction, the patient can follow up with orthopedics outpatient.

case resolution

The patient was procedurally sedated, and the hip was successfully reduced via the Waddell technique. Orthopedics placed a distal femoral traction pin and later provided definitive operative intervention for acetabular fracture.

TAKE-AWAYS

Native hip dislocations are an emergency and should be reduced within 6 hours to minimize the risk of avascular necrosis.
If a patient has a hip dislocation, be wary of concurrent injuries - from knee injuries to aortic pathology.
Techniques to reduce dislocated hips include the Allis Maneuver, Waddell technique, and the Captain Morgan technique.

AUTHOR: Alyssa Altheimer, MD, is a first year resident at Brown Emergency Medicine Residency.

FACULTY REVIEWER: Kristina McAteer, MD, is an assistant professor and clinician educator at Brown Emergency Medicine.

references

1. Cornwall R, Radomisli TE. Nerve injury in traumatic dislocation of the hip. Clin Orthop Relat Res. 2000 Aug;(377):84-91. doi: 10.1097/00003086-200008000-00012. PMID: 10943188

2. Holt GE and McCarty EC. Anteiror hip dislocation with an associated vascular injury requiring amputation. J Trauma. 2003; 55(1): 135-138.

3. Marymont JV, Cotler HB, Harris JH Jr, Miller-Crotchett P, Browner BD. Posterior hip dislocation associated with acute traumatic injury of the thoracic aorta: a previously unrecognized injury complex. J Orthop Trauma. 1990;4(4):383-7. PMID: 2266442.

4. Schmidt GL, Sciulli R, Altman GT. Knee injury in patients experiencing a high-energy traumatic ipsilateral hip dislocation. J Bone Joint Surg Am. 2005 Jun;87(6):1200-4. doi: 10.2106/JBJS.D.02306. PMID: 15930527

5. Jaskulka RA, et al. Dislocation and fracture-dislocation of the hip. J Bone Joint Surg Br. 1991; 73(3):465-469.).

6. Bucholz R, Heckman JD. Rockwood and Green Fractures in Adults. In: Rockwood and Green Fractures in Adults, 2006: pp. 2263-2263.

7. Dawson-Amoah K, Raszewski J, Duplantier N, Waddell BS. Dislocation of the Hip: A Review of Types, Causes, and Treatment. Ochsner J. 2018 Fall;18(3):242-252. doi: 10.31486/toj.17.0079. PMID: 30275789; PMCID: PMC6162140.

8. Hendley GW and Avila AA. The Captain Morgan Technique for Reduction of the Dislocated Hip. Annals of Emergency Medicine, Volume 60, Issue 1, July 2012, Pages 135-136.

9. Waddell BS, Mohamed S, Glomset JT, Meyer MS. A Detailed Review of Hip Reduction Maneuvers: A Focus on Physician Safety and Introduction of the Waddell Technique. Ortho Rev (Pavia). 2016;8(1):6253.

Posterior Hip Dislocations: ED Recognition & Management