3.2 Total Hip Arthroplasty: Postoperative Management, Hip Precautions & Dislocation Prevention

Biomechanics of Approach-Specific Hip Precautions

Following Total Hip Arthroplasty (THA), the periarticular soft-tissue envelope—including the joint capsule, short external rotators, or anterior capsule—is mechanically disrupted to allow femoral head dislocation, acetabular preparation, and prosthetic seating. Until capsular scar tissue matures and repairing tendons integrate (typically 6 to 12 weeks postoperatively), the prosthetic head is maintained within the acetabulum through muscle tone, intact ligamentous structures, and strict adherence to approach-specific positional precautions.

                      POSTOPERATIVE HIP PRECAUTIONS SUMMARY

    [POSTERIOR APPROACH PRECAUTIONS]          [DIRECT ANTERIOR PRECAUTIONS]
    - NO Hip Flexion > 90°                    - NO Hip Hyperextension
    - NO Hip Adduction past midline           - NO External Rotation with extension
    - NO Internal Rotation                    - NO Bridging in bed
    - Use abductor pillow & elevated seat     - Unrestricted flexion allowed

Posterior / Posterolateral Approach Precautions

Because the posterior capsule and short external rotators are detached, mechanical forces that drive the femoral head posteriorly against the healing repair must be strictly avoided:

1. No Hip Flexion Greater Than 90 Degrees:
   • Patients must avoid sitting in low, soft chairs, deep recliners, or standard low toilet seats.
   • Patients must never bend at the waist past 90° to pick objects off the floor, tie shoelaces, or put on socks without assistive adaptive devices (reachers, sock aids, long-handled shoehorns).
   • When sitting, knees must remain lower than hips.
2. No Hip Adduction Past Midline:
   • Patients must not cross their legs or ankles while sitting, standing, or lying in bed.
   • An abductor pillow or wedge is placed between the legs while supine or turning in bed to maintain mild abduction.
3. No Internal Rotation of the Operative Hip:
   • Patients must keep the operative foot pointing straight forward or slightly outward (external rotation is safe).
   • When pivoting or turning while ambulating, patients must take multiple small steps rather than twisting the torso over a fixed, planted operative foot.

Direct Anterior Approach (DAA) Precautions

In the DAA, the posterior capsule and external rotators are completely intact, rendering the standard 90° flexion restriction unnecessary. However, because the anterior capsule is incised or excised, anterior translation of the femoral head must be prevented:

1. No Hip Hyperextension:
   • Patients must avoid taking excessively large steps backward with the operative extremity.
   • Prone positioning and bridging exercises in bed are contraindicated during early recovery.
2. No Combined Hip Extension and External Rotation:
   • The operative leg must not be rotated outward while extended behind the body (the exact position used intraoperatively to dislocate the hip anteriorly).
3. Flexion is Permitted: Patients can sit in standard chairs, tie shoes, and climb stairs normally without the 90° flexion limitation, although extreme external rotation should be avoided.

Anterolateral / Direct Lateral Precautions

• Precautions mirror anterior protocols: avoid extreme extension and external rotation.
• In addition, active hip abduction against resistance is restricted for 6 to 8 weeks to protect the repaired anterior gluteus medius and minimus tendons from avulsion.

Prosthetic Dislocation: Presentation, Surveillance, and Emergency Management

Prosthetic hip dislocation is a major early mechanical complication, occurring in 1% to 3% of primary cases and up to 10% or more of revision procedures. The vast majority (>75%) of dislocations occur within the first 6 to 12 weeks postoperatively.

Clinical Presentation: Posterior vs. Anterior Dislocation

Recognizing the distinct physical deformity is an essential orthopaedic nursing competency:

                    PHYSICAL FINDINGS IN THA DISLOCATION

    [POSTERIOR DISLOCATION]                   [ANTERIOR DISLOCATION]
    - Lower Extremity is SHORTENED            - Lower Extremity is LENGTHENED
    - Limb is ADDUCTED                        - Limb is ABDUCTED
    - Limb is INTERNALLY ROTATED              - Limb is EXTERNALLY ROTATED
    - Prominence palpated posteriorly         - Head palpable in anterior groin
    - High Sciatic Nerve stretch risk         - High Femoral Vessel/Nerve risk

Emergency Nursing Interventions for Acute Dislocation

1. Immediate Extremity Immobilization: Instruct the patient to remain completely still in bed. Do not attempt to straighten, manipulate, or force the limb into anatomical alignment.
2. Maintain Strict NPO Status: An acute dislocation requires urgent closed reduction under procedural sedation (or general anesthesia in the operating room if locked or unstable).
3. Neurovascular Assessment: Perform immediate, focused neurovascular checks distal to the hip:
   • In posterior dislocations, assess the sciatic/peroneal nerve (sensation on dorsum of foot, great toe extension).
   • In anterior dislocations, assess femoral vascular flow (distal pedal pulses, capillary refill, skin temperature) and femoral nerve sensory distribution.
4. Diagnostic Imaging: Obtain emergent portable anteroposterior (AP) pelvis and cross-table lateral hip radiographs to confirm direction of dislocation and rule out periprosthetic fracture or component dissociation.
5. Post-Reduction Care: Following successful closed reduction (e.g., Allis maneuver or Captain Morgan technique under conscious sedation), obtain post-reduction confirmatory radiographs, verify resolution of neurovascular deficits, and apply an abduction orthosis (hip spica brace) or knee immobilizer as prescribed.

Multimodal Pain Management and Assistive Device Prescriptions

Multimodal Opioid-Sparing Analgesia

Modern total joint pathways employ preemptive and multimodal analgesic strategies designed to control acute postoperative pain while eliminating opioid-induced sedation, respiratory depression, constipation, urinary retention, and impaired motor coordination:

• Acetaminophen: 1,000 mg PO q8h scheduled (acting via central prostaglandin inhibition).
• Selective COX-2 Inhibitors (e.g., Celecoxib 200 mg PO daily or BID): Inhibits peripheral inflammatory prostaglandin synthesis without interfering with platelet COX-1 aggregation, preserving hemostasis.
• Gabapentinoids (Pregabalin 50–75 mg BID or Gabapentin 300 mg TID): Modulates alpha-2-delta calcium channels in the spinal cord, dampening neuropathic surgical hyperalgesia.
• Local Infiltration Analgesia (LIA): High-volume intraoperative periarticular injection (cocktail of ropivacaine or bupivacaine, epinephrine, and ketorolac) into the posterior capsule, external rotators, and subcutaneous tissue provides 18–24 hours of targeted regional sensory blockade without motor impairment.
• Breakthrough Opioids: Low-dose oral short-acting opioids (e.g., Oxycodone 5–10 mg PO q4–6h PRN) reserved exclusively for severe breakthrough pain.

Assistive Equipment and Home Safety Adaptations

                      ESSENTIAL POSTOPERATIVE ADAPTIVE AIDS

    [Abductor Pillow / Wedge]     [Elevated Toilet Seat]        [Adaptive Reacher / Sock Aid]
    - Placed between legs supine  - Raises seat to 17-19 in.    - Eliminates trunk flexion >90°
    - Maintains 15-20° abduction  - Prevents hip flexion >90°   - Facilitates independent dressing
    - Straps avoid peroneal neck  - Armrests aid safe push-off  - Maintains precautions at home

1. Abductor Wedge / Pillow:
   • Placed between the thighs with the wider base directed toward the knees while the patient is supine or turning onto the unoperated side.
   • Straps must be secured across the thighs and proximal calves, ensuring that straps do not compress the fibular (peroneal) neck, which could induce a compressive peroneal nerve palsy.
2. Elevated (Raised) Toilet Seat & Shower Chair:
   • Standard toilets (14–15 inches high) force the hip into >100° of flexion. Raised toilet seats (17–19 inches) with armrests maintain the hip at <80° flexion.
   • Patients are instructed to extend the operative leg forward when sitting down or standing up, pushing off from the chair armrests with both hands.
3. Sock Aids, Long-Handled Sponges, and Reachers:
   • Enable independent lower-extremity dressing and hygiene without bending past the 90° flexion threshold.
4. Safe Ambulation & Stair Climbing Instruction:
   • Progressive ambulation begins on postoperative day 0 with a front-wheeled walker.
   • Stair Climbing Rule: "Up with the good, down with the bad." When ascending stairs, the patient leads with the non-operative leg, followed by the operative leg, and lastly the crutch/cane. When descending, the crutch/cane leads first, followed by the operative leg, and lastly the non-operative leg.