Patient’s Perception on Leg Length Discrepancy After Total Hip Arthroplasty in Patients with Unilateral Crowe Type IV Developmental Dysplasia of the Hip

Figures & data

Figure 1 The full-length standing anteroposterior radiograph. (A) TD-TP: distance between the inferior aspect of teardrop (TD) and the midpoint of tibial plafond (TP). (B) CH-TP: distance between the center of hip (CH) or acetabular cup and the midpoint of tibial plafond. (C) GT-TP: distance between the apex of greater trochanter (GT) and the midpoint of tibial plafond. (D) femoral length (FL): distance between the inferior aspect of teardrop and the articular surface of medial femoral condyle. (E) tibial length (TL): distance between the center of the tibial intercondylar eminence and the midpoint of tibial plafond.

Table 1 Patient Characteristics

Variables	No Perception on LLD	Perception on LLD	P-values
Patients (n)	34	26
Gender (n)			0.444
Male	3	1
Female	31	25
Age (years)	37.7±11.7	40.8±10.9	0.289
Height (cm)	159.2±6.7	159.4±5.1	0.915
Weight (kg)	55.8±9.9	59.3±11.4	0.208
BMI (kg/m^2)	22.0±3.2	23.2±3.6	0.151
Side (n)			0.330
Right	14	14
Left	20	12

Abbreviations: LLD, leg length discrepancy; BMI, body mass index.

Table 2 Difference of Variables on Both Sides

Variables	No Perception on LLD	Perception on LLD	P-values
Difference in FL	10.5±7.7	11.0±8.3	0.807
Difference in TL	5.8±3.8	5.2±4.4	0.474
Difference in TD-TP	6.5±4.3	10.3±7.5	0.018
Difference in CH-TP	9.9±7.5	12.5±9.7	0.412
Difference in GT-TP	19.1±11.3	19.3±13.4	0.958
Difference in FL + TL	6.5±4.7	10.7±7.5	0.009

Abbreviations: LLD, leg length discrepancy; FL, femoral length; TL, tibial length; CH, center of femoral head; TP, the midpoint of tibial plafond; TD, inferior aspect of teardrop; GT, apex of greater trochanter.

Table 3 Results of Multiple Logistic Regression

Variables	Adjusted Odds Ratio*	95% Confidence Interval	P-values
Difference in TD-TP	1.157	1.022–1.310	0.021
Difference in CH-TP	1.038	0.973–1.107	0.263
Difference in GT-TP	0.996	0.953–1.042	0.870
Difference in FL+TL	1.166	1.035–1.315	0.012

Note: *The value was adjusted for gender, age, body mass index, and side.

Abbreviations: FL, femoral length; TL, tibial length; CH, center of femoral head; TP, the midpoint of tibial plafond; TD, inferior aspect of teardrop; GT, apex of greater trochanter.

Figure 2 The ROC curves for each measurement for radiographic LLD. Patients’ perception on LLD had good correlation and reliability on the difference of FL+TL and the difference of TD-TP on both sides in the full-length standing anteroposterior radiographs.

Abbreviations: LLD, leg length discrepancy; FL+TL, the sum of femoral length and tibial length; TD-TP, the distance between the inferior aspect of teardrop and the midpoint of tibial plafond.

Table 4 Intraobserver and Interobserver Variations of Measurements

Variables	Intraobserver (ICC)	Interobserver (ICC)
Difference in TD-TP	0.89	0.85
Difference in CH-TP	0.85	0.84
Difference in GT-TP	0.88	0.86
Difference in FL+TL	0.92	0.90

Abbreviations: ICC, intraclass correlation coefficient; FL, femoral length; TL, tibial length; CH, center of femoral head; TP, the midpoint of tibial plafond; TD, inferior aspect of teardrop; GT, apex of greater trochanter.