Femoroacetabular offset restoration in total hip arthroplasty; Digital templating a short stem vs a conventional stem

Table 1 Patient and radiological characteristics

Patient characteristic	(n = 100)
Female, %	72
Age, mean (range)	66.7 (41-90)
BMI, mean (range)	27.3 (18.7-42.8)
Right hip, %	54
Indication, %
Primary coxarthrosis	98
Perthes coxarthrosis	1
Posttraumatic coxarthrosis	1
Femoral offset (mm), mean (range)	47 (30.5-67)
Acetabular offset (mm), mean (range)	32.5 (22.5-47.5)
Femoro-acetabular offset (mm), mean (range)	80 (62-113)
CCD-angle (°)	128.6 (114.5-146)

CCD angle: Caput-colllum-diaphyseal angle; CI: Confidence interval.

Table 2 Determinants correlated with offset restoration

	β coefficient (95%CI)	R2	P value
Student
CCD-angle (short stem)	-0.01 (-0.03, -0.02)	0.002	0.62
CCD-angle (conventional stem)	0.34 (0.18, 0.50)	0.15	< 0.001
Pre-templating FAO (short stem)	-0.004 (-0.02, 0.01)	0.002	0.62
Pre-templating FAO (conventional stem)	-0.45 (-0.53, -0.38)	0.63	< 0.001
Resident
CCD-angle (short stem)	-0.01 (-0.04, 0.02)	0.004	0.55
CCD-angle (conventional stem)	-0.25 (-0.10, 0.41)	0.09	0.002
Pre-templating FAO (short stem)	-0.02 (-0.04, 0.00)	0.03	0.05
Pre-templating FAO (conventional stem)	-0.44 (-0.50, -0.38)	0.68	0.000

FAO: Femoroacetabular offset; CCD angle: Caput-colllum-diaphyseal angle; CI: Confidence interval.

Table 3 Post-templating measurements of radiographs (n = 100)

	Short stem	Conventional stem
Post-templating measurements
Femoral offset (mm), mean (range)	51.5 (3679)	48 (3757.5)
Acetabular offset (mm), mean (range)	28.5 (23.535.5)	28.5 (23.535.5)
Femoro-acetabular offset (mm), mean (range)	80 (62112.5)	76.5 (63.589.5)
Difference pre- and post-templating
Femoral offset (mm), mean (range)	4 (-2.513)	1 (-11.511)
Acetabular offset (mm), mean (range)	-4 (-142.5)	-4 (-142.5)
Femoro-acetabular offset (mm), mean (range)	0 (-42)	-3 (-245)
Restoration of femoral offset, %	100	91
Restoration of femoro-acetabular offset, %	100	72

Table 4 Intra-observer reliability

	Student	Resident
Pre-templating FAO	0.99	0.99
Post-templating FAO short stem	0.98	0.98
Post-templating FAO conventional stem	0.92	0.93
CCD-angle	0.93	0.94

FAO: Femoroacetabular offset; CCD angle: Caput-colllum-diaphyseal angle.

Table 5 Inter-observer reliability

	Student vs Resident	Student vs Hip surgeon	Resident vs Hip surgeon
Pre-templating FAO	0.98	0.93	0.95
Pre-templating FO	0.97	0.93	0.94
Pre-templating AO	0.97	0.91	0.92
Post-templating FAO short stem	0.97	0.93	0.95
Post-templating FAO conventional stem	0.90	0.84	0.86
CCD-angle	0.87	0.81	0.76

FAO: Femoroacetabular offset; CCD angle: Caput-colllum-diaphyseal angle.