Bony impingement depends on the bone morphology of the hip after total hip arthroplasty

Abstract

Purpose The purpose of this study was to evaluate whether the bone morphology of the hip affects the range of motion (ROM) in total hip arthroplasty (THA). Methods Using the CT data of 63 patients who underwent THA, we calculated the ROM of flexion (Flex), internal rotation (Int-R) and external rotation (Ext-R) using 3D dynamic analysis software. We measured the distance between the anterior surface of the stem and anterior aspect of the greater trochanter (GTa length) at the cutting point and between the tip of the antero-inferior iliac spine (AIIS) and coronal plane of both femoral heads (AIIS length), as a parameter of the femur and pelvis, respectively. The relationship between the ROM, bone anatomy and impingement site was evaluated. Results We found a significant decrease in the ROM of Flex and the Int-R to be inversely proportional to the GTa and AIIS length. In Flex and Int-R, the anterior intertrochanteric region often impinges on the AIIS in patients with larger bone anatomy. Conclusions We demonstrated that the bone morphology of the hip substantially affects the ROM of Flex and Int-R, especially in patients with large bone anatomy. For these patients we should consider bony impingement in THA.

Bone-to-Bone and Implant-to-Bone Impingement: A Novel Graphical Representation for Hip Replacement Planning

“…2,5,7 However, there are still many post-operative complications associated with THA, with aseptic loosening and dislocation being two of the most common. 30,33 Although the overall dislocation rate has decreased over the past two decades, 15,26 a significant number of patients continue to experience recurrent episodes. Such recurrent dislocations, defined as two or more occurrences, 10 occurred in over 60% of patients at a minimum follow-up of 1 year after the first dislocation 10,26 and over 50% of these patients required revision surgery.…”

“…16,28 The risk factors that are associated with impingement include design of implants, and their orientations and alignments, and the surgical approaches. 4,10,19,31,33 Additionally, patient related factors such as gender, advanced age, history of previous hip surgery, pelvic tilt and bony structures around the hip increase the risk of impingement and subsequently recurrent dislocation. 8,10,11,33 Bartz et al 1 classified dislocation mechanisms into three categories based on impingement type as follows: (a) prosthetic impingement (PI) which occurs when the prosthetic femoral neck comes in contact with the rim of the liner/cup, (b) bone-to-bone impingement (BTBI) which is the impingement between the osseous femur and the osseous pelvis, and (c) spontaneous dislocation.…”

“…Although the factors which are associated with spontaneous dislocation are not fully identified, it is presumed that the soft tissue imbalance, weakness of the muscle, or/and contracture of the hip joint might increase its risk. 33 Other than these three types, there is a possibility of implant-tobone impingement (ITBI) which occurs when the prosthetic femoral stem comes in contact with pelvis or the bony femur comes into contact with the rim of the liner/cup. PI is associated with the acetabular and femoral implants only and has a known set of variables such as implant design and their positions and orientations on native bone geometries.…”

“…It mainly depends on the bony structures around the hip along with the level of osteotomy, and the prosthetic geometries and their orientations (e.g., femoral offset and version etc.). 31,33 It occurs due to unintended contact between femoral bones (e.g., greater trochanter, lesser trochanter, femoral neck) and acetabular margin (which is called ''limbus acetabuli''), ilium or ischium (the anterior superior iliac spines is part of the ilium). 11,32,35 ITBI could be partially controlled by changing implant designs and their positions and orientations.…”

“…Therefore, it is usually recommended to recreate genuine bone morphology by resecting osteophytes completely during THA to avoid post-THA BTBI and ITBI. 14,21,31,33 However, the risk assessment of post-THA BTBI and ITBI is mostly carried out intra-operatively by the surgeons based on their anatomical knowledge in recognising the difference between ''genuine'' and ''osteophytic'' bone. Therefore, it depends on the surgeons' experiences, and intuitive anatomical reasoning, which are subjective and qualitative in nature.…”