Background
Methods
Patients and follow-up
Implant systems
Procedure
Pre-2008, Group 1 (N = 121) | Post-2008, Group 2 (N = 242) |
P-value | |
---|---|---|---|
Sex (no. of hips)
| |||
MALE | 35 (29 %) | 64 (26 %) | 0.6171 |
FEMALE | 86 (71 %) | 178 (74 %) | |
DECEASEDa
| 3 (2.5 %) | 1 (0.4 %) | 0.0751 |
Follow-up Mean Years
| 6.4 ± 2.31 | 2.6 ± 1.51 | <0.0001b
|
Case Date Range
| 1/2001–7/2008 | 7/2008–7/2013 | -- |
Age (yr)
| 48 ± 8.37 | 52 ± 7.05 | <0.0001b
|
BMI
| 26 ± 5.04 | 26 ± 5.08 | 1.000 |
T-score
| −0.34 ± 1.44 | −0.40 ± 1.10 | 0.6599 |
Overall Failures (no. of hips)
| 16 (13.2 %) | 2 (0.8 %) | <0.0001b
|
2-Year Raw Failures (no. of hips)
| 8 (6.6 %) | 2 (0.8 %) | 0.0015b
|
7-Year Survivorship (no. of hips)
| 108 (89.3 %) | 240 (99.2 %) | <0.0001b
|
Dysplasia Grade (no. of hips)
| |||
Dysplasia I | 37/51 (73 %) | 188/241 (78 %) | 0.4009 |
Dysplasia II | 10/51 (20 %) | 49/241 (20 %) | 0.9045 |
Dysplasia III | 0/51 (0 %) | 0/241 (0 %) | 1.000 |
Dysplasia IV | 0/51 (0 %) | 0/241 (0 %) | 1.000 |
Dysplasia Osteotomy | 4/51 (7.8 %) | 4/241 (1.7 %) | 0.0139b
|
Grade Unrecorded | 70/121 (58 %) | 1/242 (0.4 %) | <0.0001b
|
ASA Score
| 1.6 ± 0.55 | 1.6 ± 0.56 | 1.000 |
Femoral Component <48 mm (no. of hips)
| 46/121 (38 %) | 79/242 (33 %) | 0.3077 |
Femoral Component Size
| 48.1 ± 3.45 | 47.0 ± 2.91 | 0.0016b
|
Normalized to standing intraoperative x-ray
Postoperative protocol
Metal ion testing
Normala
| Optimalb
| Acceptablec
| Problematicc
| Potentially Toxicb
| |
---|---|---|---|---|---|
Unilateral | |||||
• Co | <1.5 μg/L | <4.0 μg/L | 4–10 μg/L | 10–20 μg/L | >20 μg/L |
• Cr | <1.5 μg/L | <4.6 μg/L | 4.6–10 μg/L | 10–20 μg/L | >20 μg/L |
Bilateral | |||||
• Co | <1.5 μg/L | <5.0 μg/L | 5–10 μg/L | 10–20 μg/L | >20 μg/L |
• Cr | <1.5 μg/L | <7.4 μg/L | 7.4–10 μg/L | 10–20 μg/L | >20 μg/L |
Clinical and radiological analysis
Statistical methods
Results
Variable | Group 1 | Group 2 |
P-value |
---|---|---|---|
Length of Incision (in) | 4.5 ± 2.63 | 4.2 ± 0.49 | 0.0866 |
Operation Time (min) | 114 ± 18.54 | 95 ± 14.17 | <0.0001a
|
Estimated Blood Loss (mL) | 257 ± 100.07 | 142 ± 76.60 | <0.0001a
|
Hospital Stay (days) | 2.6 ± 1.02 | 1.7 ± 0.75 | <0.0001a
|
Variable | Group 1 | Group 2 |
P-value |
---|---|---|---|
Preoperative
| |||
HHS Scorea
| 53 ± 12.44 | 57 ± 14.91 | 0.0115* |
Postoperative
| |||
HHS Score | 98 ± 4.10 | 98 ± 5.49 | 1.000 |
UCLA Score | 6.3 ± 1.24 | 7.0 ± 2.05 | 0.0006* |
VASb Pain: Regular | 0.5 ± 0.90 | 0.2 ± 0.98 | 0.0050* |
VAS Pain: Worst day | 2.3 ± 2.34 | 1.2 ± 2.17 | <0.0001* |
Combined ROMc
| 289 ± 49.5 | 291 ± 55.5 | 0.7376 |
Radiographic Data
| |||
AIAd
| 46 ± 8.03 | 34 ± 5.36 | <0.0001* |
Met RAIL Criteria (# Hips, %) | 93 (76 %) | 239 (99 %) | <0.0001* |
Radiolucency (# Hips, %) | 2 (1.7 %) | 0 (0 %) | 0.0444* |
Osteolysis (# Hips, %) | 0 (0 %) | 0 (0 %) | 1.000 |
Variables | Group 1 (Pre-2008) | Group 2 (Post-2008) |
P-values between Group 1 and Group 2 | |||||
---|---|---|---|---|---|---|---|---|
Unilateral (N = 51) | Bilateral (N = 50) |
P-value | Unilateral (N = 118) | Bilateral (N = 72) |
P-value | Unilat I vs II | Bilat I vs II | |
Coa (μg/L) | 1.7 ± 1.90 | 3.1 ± 2.32 | 0.0013b
| 1.3 ± 0.93 | 2.2 ± 1.33 | <0.0001b
| 0.0679 | 0.0076b
|
Cra (μg/L) | 1.6 ± 2.15 | 2.5 ± 2.04 | 0.0235b
| 1.2 ± 1.10 | 1.9 ± 1.67 | 0.0006b
| 0.1107 | 0.0775 |
Follow-Up Date (Yrs) | 5.4 ± 1.93 | 6.5 ± 2.24 | 0.0095b
| 2.2 ± 1.14 | 2.5 ± 1.16 | 0.0821 | <0.0001b
| <0.0001b
|
#, % Patients Tested | 105 (87 %) | -- | 187 (77 %) | -- | 0.0316b
| |||
#, % Levels Converted | 17 (33 %) | 21 (42 %) | 0.3320 | 26 (22 %) | 19 (25 %) | 0.5961 | 0.1416 | 0.0510 |
#, % Revised (Excluded) | 15 (12 %) | 6 (5 %) | 0.0394b
| 2 (0.8 %) | 0 (0 %) | 0.1556 | <0.0001b
| 0.0005b
|
#, % Revised AWRF (Excluded) | 2 (1.7 %) | 2 (1.7 %) | 1.000 | 0 (0 %) | 0 (0 %) | 1.000 | 0.0444b
| 0.0444b
|
Normal (#, %) | 32 (56 %) | 6 (12.5 %) | <0.0001b
| 86 (77 %) | 20 (28 %) | <0.0001b
| 0.0058b
| 0.0466b
|
Optimal (#, %) | 49 (86 %) | 35 (73 %) | 0.0949 | 111 (99 %) | 63 (88 %) | 0.0007b
| 0.0003b
| 0.0434b
|
Acceptable (#,%) | 7 (12.3 %) | 12 (25 %) | 0.0910 | 3 (2.7 %) | 9 (12.5 %) | 0.0085b
| 0.0124b
| 0.0767 |
Problematic (#, %) | 1 (1.8 %) | 1 (2.1 %) | 0.9045 | 0 (0 %) | 0 (0 %) | 1.000 | 0.1585 | 0.2187 |
Potentially Toxic (#, %) | 0 (0 %) | 0 (0 %) | 1.000 | 0 (0 %) | 0 (0 %) | 1.000 | 1.000 | 1.000 |
Type | Group 1 | Group 2 |
P-value |
---|---|---|---|
# Cases | 121 | 242 | -- |
Acetabular Failures
| |||
Adverse Wear | 4 (3.3 %) | 0 (0 %) | 0.0045* |
Loose Acetabular Component | 1 (0.8 %) | 0 (0 %) | 0.1556 |
Failure of Acetabular Ingrowth | 6 (5.0 %) | 0 (0 %) | 0.0005* |
Acetabular Component Shift | 0 (0 %) | 1 (0.4 %) | 0.4777 |
Femoral Failures
| |||
Femoral Neck Fracture | 1 (0.8 %) | 1 (0.4 %) | 0.6171 |
Femoral Head Collapse | 2 (1.7 %) | 0 (0 %) | 0.0444* |
Loose Femoral Component | 1 (0.8 %) | 0 (0 %) | 0.1556 |
Other Failures
| |||
Unexplained Pain | 1 (0.8 %) | 0 (0 %) | 0.1556 |
TOTAL FAILURES
|
16 (13.2 %)
|
2 (0.8 %)
|
<0.0001*
|
Type | Group 1 | Group 2 |
P-value |
---|---|---|---|
# Cases | 121 | 242 | -- |
Acetabular Failures
| |||
Failure of Acetabular Ingrowth | 5 (4.1 %) | 0 (0 %) | 0.0015* |
Acetabular Component Shift | 0 (0 %) | 1 (0.4 %) | 0.4777 |
Femoral Failures
| |||
Femoral Neck Fracture | 1 (0.8 %) | 1 (0.4 %) | 0.6171 |
Femoral Head Collapse | 2 (1.7 %) | 0 (0 %) | 0.0444* |
TOTAL FAILURES
|
8 (6.6 %)
|
2 (0.8 %)
|
0.0015*
|
Type | Group 1 | Group 2 |
P-value |
---|---|---|---|
# Cases | 121 | 242 | -- |
Complications
| |||
Acetabular Complications
| |||
Acetabular Component Shift | 1 (0.8 %) | 1 (0.4 %) | 0.6171 |
Other Complications
| |||
Psoas Tendonitis | 1 (0.8 %) | 0 (0 %) | 0.1556 |
Hip Dislocation | 1 (0.8 %) | 1 (0.4 %) | 0.6171 |
Abductor Tear | 1 (0.8 %) | 0 (0 %) | 0.1556 |
Deep Vein Thrombosis | 0 (0 %) | 1 (0.4 %) | 0.4777 |
TOTAL COMPLICATIONS
| 4 (3.3 %) | 3 (1.2 %) | 0.1770 |
Reoperations
| |||
Femoral Neck Fracture | 1 (0.8 %) | 0 (0 %) | 0.1556 |
Late IT Fracture | 0 (0 %) | 1 (0.4 %) | 0.4777 |
Fascial Healing Defect | 0 (0 %) | 1 (0.5 %) | 0.4777 |
TOTAL REOPERATIONS
| 1 (0.8 %) | 2 (0.8 %) | 1.000 |
Discussion
Study | Procedure | Prosthesis | Date range | Diagnosis | Patient cohort | Avg FU (Yrs) | Survivorship | ||
---|---|---|---|---|---|---|---|---|---|
Hips | Female | FU | Rate | ||||||
Amstutz et al.
| HRA | Conserve Plus | 1996–2006 | Dysplasia | 103 | 78 % | 4.8 | 8 | 92 % |
McBryde et al.
| HRA | Birmingham | 1997–2004 | Dysplasia | 96 | 81 % | 4.4 | 5 | 97 % |
Naal et al.
| HRA | Birmingham | 2002–2005 | Dysplasia | 32 | 56 % | 3.6 | 5 | 94 % |
Pagnano et al.
| THA | Charnley THA | 1969–1980 | Dysplasia Crowe 2 | 145 | 82 % | 14 | 7 12 | 73 % 56 % |
Numair et al.
| THA | Charnley THA | 1965–1987 | Dysplasia Crowe 1–3 | 136 | 63 % | -- | 10 | 98 % |
Linde et al.
| THA | Charnley THA | -- | Dysplasia | 129 | -- | -- | 5 10 | 93 % 89 % |
Millis et al.
| Bernese Osteotomy | -- | 1991–1998 | Dysplasia | 135 | 86 % | 9 | 5 10 | 96 % 84 % |
Adelani et al.
| Revision THA | -Varies- | 1996–2006 | <55 years old | 103 | 66 % | 6.7 | 6.7 | 69 % |
Current Study Group 1 | HRA | Corin Hybrid, Biomet ReCap™ Hybrid | 2001–2008 | Dysplasia | 121 | 71 % | 6.4 | 7 12 | 90 % 86 % |
Current Study Group 2 | HRA | Biomet ReCap™ Uncemented | 2008–2013 | Dysplasia | 242 | 74 % | 2.6 | 7 | 99 % |
Acetabular component fixation
Acetabular component alignment
Bone protection program and uncemented fixation
Conclusions
-
With sufficient experience, hip resurfacing arthroplasty (HRA) can be performed with a success rate that compares favorably to that of standard stemmed total hip arthroplasty in dysplasia patients (99 % 7-year survivorship).
-
Dislocations (0.5 %) and revisions for instability (0 %) are rare when HRA is used in high-risk (for instability) dysplasia patients.
-
Adverse wear related failures (AWRF) can be completely eliminated, and optimal ion levels can routinely be achieved in high-risk (for AWRF) dysplasia patients if the Relative Acetabular Inclination Limit (RAIL) is observed.
-
The RAIL can be achieved in a high percentage of cases (99 %) when a normalized intraoperative x-ray technique is used.
-
Failure of acetabular component fixation can be avoided (0 %) if an acetabular component with a supplemental fixation option is selectively (5 %) employed.
-
Early femoral failures can be reduced when a comprehensive bone management protocol is followed.
-
Uncemented femoral components are highly successful, but we do not have the data to show if the lower rate of femoral complications observed can be assigned to them.