Offset restoration in total hip arthroplasty: Important: A current review

Abstract

Normal vertical and horizontal offset is essential for hip biomechanics, muscle functioning and gait pattern. Total hip arthroplasty (THA) should aim to restore normal offset with implantation of femoral and acetabular components. This would be possible with proper preoperative planning, templating and ensuring implant options are available for offset restoration. Templating is essential for understanding the vertical and horizontal offset change, especially in hip arthritis presenting late with significant limb length discrepancy at THA. Planning should include appropriate soft tissue releases and the use of ideal implants to achieve restoration of horizontal and vertical offset. Under correction of horizontal offset at THA for fracture neck of femur could result in abductor fatigue, limp and increased wear. Restoration of horizontal offset is imperative at THA for a fractured neck of the femur to achieve optimal abductor function. Horizontal offset is necessary for optimal abductor muscle tension and function. Revision THA for acetabular bone loss would require hip center restoration with the acetabular and femoral offset correction to achieve limb length correction and abductor length. The inability to achieve vertical and horizontal offset correction could lead to dislocation or signs of abductor fatigue. Careful vertical and horizontal femur offset restoration is required for normal hip biomechanics, decreased wear and increased longevity.

Keywords: Offset; Vertical; Horizontal; Total hip arthroplasty; Templating; Restoration

Core Tip: Total hip arthroplasty (THA) requires careful attention to achieve restoration of both the vertical and horizontal offset. The vertical offset is critical to establish the correct limb length; inadequate restoration of vertical offset results in limb length discrepancy and poor clinical outcomes. The horizontal offset plays a role in obtaining optimal abductor tension and function, allowing for normal gait. Failure to achieve normal horizontal offset leads to sub-optimal abductor function, fatigue, limp, increased wear, and possible THA instability. Pre-operative templating and intra-operative execution of this plan allow for offset restoration, appropriate soft-tissue releases, and suitable implant selection, which ultimately results in hip center restoration and recreation of normal hip biomechanics.