Migration analysis of a metaphyseal anchored short-stem hip prosthesis

Figures & data

Figure 1. a. Reference points for EBRA-FCA analysis. A: center point of head; B: tip of stem; C: stem reference line; D: implant shoulder; E: greater trochanter; F: lesser trochanter. b. Experimental set-up for the in vitro evaluation.

Table 1. Size of the femur relative to the size of the non-migrated stems (mean (range))

Stem size	Point 1 ^a , mm	Point 2 ^b , mm
0	22 (19–25)	10 (9–11)
1	24 (20–27)	11 (9–16)
2	27 (24–29)	11 (10–12)
3	28 (23–32)	13 (9–16)
4	29 (22–32)	13 (11–15)
5	31 (26–40)	14 (11–18)
6	36 (35–37)	14 (12–15)

^a Midline lesser trochanter (endosteal distance).

^b 10 cm below the midline of the lesser trochanter (endosteal distance).

Table 2. Validation of the EBRA-FCA method for the short stem and conventional stem. Values are mm

	SHA ^a	THA ^b
Rotation
Flexion/extension 20°/5° and 16°/5° ^a	–1.5 / +0.9	± 1.4
Internal/external rotation 10°/10° and 5°/5°	–0.2 / +0.2	± 0.7
Migration
Controlled migration 0–6 and 0–7 mm ^a	–0.5 / +0.4	± 0.5

^a Short-stem hip arthroplasty, present study.

^b Total hip arthroplasty (Ilchmann et al. 2006).

Figure 2. Subsidence of the short-stem implants at the final follow-up. The dashed line represents the critical threshold of –1.5 mm within the first 2 years (Krismer et al. 1999).

Table 3. Data on the 6 migrated stems (5 patients)

A	B	C	D	E	F	G	H	I
1 - left	5.5	B	M	2	30/12	AVN		4 (1/1/3)
2 - right	5.2	B	M	2	31/11	AVN		4 (1/1/3)
3	7.0	B	M	4	28/13	Osteoarthritis	Parkinson	3 (0/0/3)
4	4.4	B	F	2	25/9	Dysplasia		0 (0/0/3)
5	11.1	A	M	2	30/14	AVN	Chronic alcohol abuse	0 (0/0/0)
6	5.5	A	M	2	32/15	AVN	High-dose steroids	20 (3/3/14)

A Stem

B Migration, mm

C Migration pattern

D Sex

E Implant Size

F Femur size at point 1 / point 2, mm

G Diagnosis

H Secondary diagnosis

I WOMAC: total WOMAC score (pain/stiffness/function).

Ilchmann T, Eingartner C, Heger K, Weise K. Femoral subsidence assessment after hip replacement: an experimental study. Ups J Med Sci 2006; 111 (3):361-9.

 PubMed Web of Science ®Google Scholar

Krismer M, Biedermann R, Stockl B, Fischer M, Bauer R, Haid C. The prediction of failure of the stem in THR by measurement of early migration using EBRA-FCA. Einzel-Bild-Roentgen-Analyse-femoral component analysis. J Bone Joint Surg (Br) 1999; 81 (2):273-80.

 PubMedGoogle Scholar