TOTAL HIP ARTHROPLASTY

SUMMARY: Complications of Total Hip Arthroplasty are common Causes of medical malpractice Action.  Postoperative neuropathy, leg length discrepancy and infection should arguably explicitly appear in documentation of disclosure for Informed Consent. 

Replacement of the diseased hip joint by a ceramic prosthesis has become a standard operative procedure.  Various complications are relatively common and should feature in the documented disclosure for informed consent.  Some potentially identifiable and avoidable factors have been identified. 

Postoperative Neuropathy

Prevalence is up to 3% after primary arthroplasty, as high as 7-8% after revision arthroplasty. ¹

The nerves affected are usually the peroneal or sciatic - injury to the femoral nerve is uncommon, to the obturator nerve rare. 

The cause ² is unclear in up to 50% of cases ³, but one or more of the following may apply or should be explored in Discoveries and medical expert opinion:  direct trauma during surgery, tension due to leg lengthening or intra-operative limb positions, compression from retractors, postoperative hematoma, methylmethacrylate (cement) extrusion, trauma by cerclage wires, acetabular screws or protrusio rings, posterior rather than anterior or transtrochanteric approach. 

Only 20% of affected patients completely recover function by 2 years.

Leg Length Discrepancy

Other causes such as tight adductors should be excluded clinically. 

Pre-operatively leg length should be accurately measured, and the correct radiographs undertaken for surgical planning and templating of the size and placement of the acetabular component, the level of the femoral osteotomy, and the size and type of femoral stem.^{4 []}

Intra-operative measurements and radiographs should be taken to confirm the correctness of the size and placement of the prosthesis. ^{4 []}

Established limb length discrepancy can be corrected postoperatively only by replacing the prosthesis (revision arthroplasty). 

In the early days of total hip arthroplasty, average limb length discrepancy of 16 mm was considered acceptable ⁵, whereas 10 mm is now achievable⁶  and even 5 mm in centres of excellence⁷. 

However, up to a quarter of patients will have a symptomatic discrepancy that requires a heel lift ⁸. 

Nevertheless, severity of discrepancy may not determine functional outcome or patient satisfaction ⁹. 

Infection

The prevalence of infection following total hip arthroplasty is up to 7-8%. ¹⁰

Any embedded foreign-body may become infected.  Identified Causal factors in increased infection rates include various concurrent medical conditions, ¹¹ the timing and dosage of preoperative antibiotics, total operative time, surgical technique and/or handling of the soft tissues, the volume of operating-room traffic, complexity of the reconstruction ¹⁰ and surgeon and hospital volume^{. 12}

Mortality is up to 2-3%, ¹³ and there is a 10% probability that a joint once infected will later become re-infected. 

Dislocation

Instability of total hip arthroplasty occurs after 2-5% of primary operation, twice that percentage in revision arthroplasty ^14a.  Factors in the patient ^14b and the surgery ^14c have been identified. 

Aseptic Loosening

Loosening of the femoral prosthesis is a relatively frequent complication, particularly in the young and active ¹⁵.  Improving surgical technique and technological advances may be slowly reducing the frequency of the problem. 

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