True or Apparent Leg Length Discrepancy

Cheng

Chinese Medical Journal

2015

Background:Total hip arthroplasty (THA) is one of the most effective treatments for phase III and IV hip arthrosis. Lower limb length balancing is one of the determining factors of a successful surgery, particularly in patients with developmental dysplasia of the hip (DDH). The purpose of this study was to evaluate the postoperative change in intra-pelvic obliquity (intra-PO) angle in the coronal plane and its effects on leg length discrepancy (LLD) within 2 years.Methods:A total of 78 patients (70 females, 8 males) were enrolled in this study. All patients were suffering from DDH with varying degrees of LLD. Pelvic plain radiographs were collected before and after the operation. The intra-PO angles were measured 0, 0.5, 1 and 2 years after THA. At the same time, postoperative LLD was measured with blocking test.Results:PO changed significantly in the first year after THA surgery (0 year vs. 0.5 year, P < 0.01; 0.5 year vs. 1 year, P < 0.01), and the changing value of intra-PO angle (ΔPO) slowed down substantially during the first 2 years after THA (0.5 year vs. 0.5–1 year, P < 0.01; 0.5–1 year vs. 1–2 years, P < 0.01). With the change in intra-PO angle, LLD also got narrow within the 1st year (0 year vs. 0.5 year, P < 0.01; 0.5 year vs. 1 year, P < 0.01). Elderly patients had a smaller intra-PO angle reduction (Group A vs. Group B, P = 0.01; Group B vs. Group C, P < 0.01).Conclusions:Intra-PO angle and LLD gap narrowed with time after THA surgery. In particular, elderly patients had smaller change in intra-PO angle.

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Changes in Intra-pelvic Obliquity Angle 0–2 Years After Total Hip Arthroplasty and Its Effects on Leg Length Discrepancy

Cheng

Chinese Medical Journal

2015

“…Thirty-two percent, 11%, and 7% of patients complain of a sense of surgical leg prolongation—a perceived leg length discrepancy (PLLD)—beyond the radiographic leg length discrepancy who underwent unilateral THA at 3 weeks, 3 months, and 1 year postoperatively, respectively 11 ) . The PLLD after unilateral THA can often be caused by a pelvic tilt as a result of a functional leg length discrepancy (LLD) 12 ) . Compared with patients without PLLD, THA patients with PLLD after unilateral THA have a smaller hip adduction range of motion during gait 13 ) .…”

Section: Introductionmentioning

confidence: 99%

Relationship of early postoperative perceived leg length discrepancy to the progression of osteoarthritis in the contralateral hip after unilateral total hip arthroplasty—a retrospective cohort study using propensity score matching

Kawabata

Kimura

2023

J Phys Ther Sci

[Purpose] This study aimed to identify the relationship between the early postoperative perceived leg length discrepancy after unilateral total hip arthroplasty and the progression of osteoarthritis in the contralateral hip. [Participants and Methods] This was a retrospective cohort study of 65 patients who underwent primary unilateral total hip arthroplasty for bilateral hip osteoarthritis. The minimum joint space width of the contralateral hip was measured preoperatively. The change in minimum joint space width one year postoperatively compared with preoperatively was measured. At three weeks postoperatively, patients were divided into the perceived and non-perceived leg length discrepancy groups using the block test. Patients with a perceived leg length discrepancy of 2 mm or more and less than 2 mm were grouped into the perceived and non-perceived leg length discrepancy groups, respectively. Before and after propensity score matching, the change in minimum joint space width between the two groups from the preoperative period to one year postoperatively was compared. [Results] In the pre-propensity matching sample, there was no significant difference in the change in minimum joint space width between the two groups. In the post-propensity matching sample, the change in minimum joint space width in the perceived leg length discrepancy group was significantly larger than that in the non-perceived leg length discrepancy group. [Conclusion] The early postoperative perceived leg length discrepancy after unilateral total hip arthroplasty may affect the progression of osteoarthritis in the contralateral hip.

“…Based on etiology, LLD can be conceptualized as falling into one of two main categories: 1) structural or ‘true’ LLD and 2) functional or ‘apparent’ LLD [24, 25]. True LLD is attributable to actual shortening of bony structures, usually as a result of defective pelvic or femoral anatomy.…”

Section: Introductionmentioning

confidence: 99%

Effects of pelvic obliquity and limb position on radiographic leg length discrepancy measurement: a Sawbones model

Hamad¹,

Livshetz

Sood³

et al. 2022

J EXP ORTOP

Purpose Potential sources of inaccuracy in leg length discrepancy (LLD) measurements commonly arise due to postural malalignment during radiograph acquisition. Preoperative planning techniques for total hip arthroplasty (THA) are particularly susceptible to this inaccuracy, as they often rely solely on radiographic assessments. Owing to the extensive variety of pathologies that are associated with LLD, an understanding of the influence of malpositioning on LLD measurement is crucial. In the present study, we sought to characterize the effects of varying degrees of lateral pelvic obliquity (PO) and mediolateral limb movement in the coronal plane on LLD measurement error (ME). Methods A 3-D sawbones model of the pelvis with bilateral femurs of equal-length was assembled. Anteroposterior pelvic radiographs were captured at various levels of PO: 0°, 5°, 10°, and 15°. At each level of PO, femurs were individually rotated medio-laterally to produce 0°, 5°, 10°, and 15° of abduction/adduction. LLD was measured radiographically at each position combination. For all cases of PO, the right-side of the pelvis was designated as the higher-side, and the left as the lower-side. Results At 0° PO, 71% of tested variations in femoral abduction/adduction resulted in LLD ME < 0.5-cm, while 29% were ≥ 0.5-cm, but < 1-cm. ME increased progressively as one limb was further abducted while the contralateral limb was simultaneously further adducted. The highest ME occurred with one femur abducted 15° and the other adducted 15°. Similar magnitudes of ME were seen in 98% of tested femoral positions at 5° of PO. The greatest ME (~ 1 cm) occurred at the extremes of right-femur abduction and left-femur adduction. At 10° of PO, a higher prevalence of cases exhibited LLD ME > 0.5-cm (39%) and ≥ 1-cm (8%). The greatest errors occurred at femoral positions similar to those seen at 5° of PO. At 15° of PO, half of tested variations in femoral position resulted in LLD ME > 1-cm, while 22% of cases produced errors > 1.5-cm. These clinically significant errors occurred at all tested variations of right-femur abduction, with the left-femur in either neutral position, abduction, or adduction. Conclusion This study aids surgeons in understanding the magnitude of radiographic LLD ME produced by varying degrees of PO and femoral abduction/adduction. At a PO of ≤5°, variations in femoral abduction/adduction of up to 15° produce errors of marginal clinical significance. At PO of 10° or 15°, even small changes in mediolateral limb position led to clinically significant ME (> 1-cm). This study also highlights the importance of proper patient positioning during radiograph acquisition, demonstrating the need for surgeons to assess the quality of their radiographs before performing preoperative templating for THA, and accounting for PO (> 5°) when considering the validity of LLD measurements.