Implant fracture of modular revision stems is a major complication after total hip arthroplasty revision (rTHA). Studies looking at specific modular designs report fracture rates of 0.3% to 0.66% whereas fractures of monobloc designs are only reported anecdotally. It is unclear whether the overall re-revision rate of modular designs is higher and if, whether stem fractures or other revision reasons are responsible for this elevation.

All revisions within 5 years after implantation of a revision stems (n₀=13,900; n₅=2506) were analysed using Cox regression with design (modular: n=17, monobloc: n=27), BMI, Sex and Elixhauser Score as independent variables. One stage and two stage revisions were analysed separately (1-stage: modular n= 7,102; monobloc n= 4,542; 2-stage: 1,551 / 704). The revision volume of the hospitals was also considered (low: <20 revisions, medium: 21–50 revisions, high: >50 revisions).

For the 1-stage revisions, the re-revision risk after 4 years was 14,3% [13.2%, 15.5%] for monobloc and 17.4% [16.40%, 18.40%] for modular stems (p< 0.001). Stem fracture was the reason for re-revision in 2.4% of the modular (fracture rate 0.42%) and 0.6% of the monobloc revisions. The difference in re-revision rates between the designs was mainly due to differences in dislocation and stem loosening. For the 2-stage revisions, the revision risks for either design were similar (21.7% [18,5%, 25.4%] vs. 23.0% [20.8%, 25.4%]; p=0.05). Patient characteristics influenced the comparison between the two designs in the 1-stage group but very little in the 2-stage group.

Modular revision stem fractures only contribute very minor to re-revision risk. In 2-stage revisions, no difference in overall re-revision rates between designs was observed. This might indicate that the differences observed for 1-stage procedures are due to differences between the patient cohorts, not reflected by the parameters available or surgeon choice.

Introduction: This minimally invasive (MI) anterior approach has been developed to improve patients’ rehabilitation and long-term function. It is aligned along the interneural plane of Smith-Peterson, with complete preservation of the musculotendinous structures. The femoral neck oeteotomy is performed without dislocation of the joint or resection of the joint capsule. As there is also no additional traction applied to the soft tissues it is one of the most tissue sparing techniques available for THA. The outcome was recorded prospectively and is compared with retrospective data of a conventional lateral approach. No other variables other than the surgical technique were changed for the protocol.

Methods: 55 patients underwent traditional THR (lateral approach) surgery in 2003 and 216 consecutive, non selected patients having an anterior minimal invasive procedure during 2004/05 were followed up for an independent review.

Results: The two groups of patients were comparable in terms of age and BMI. Blood loss dropped by 42%. Hospital stay was reduced by 2.1 days (+/−0.6.) Cup inclination was 45.56 (+/−3.4) in the traditional group and 44.8 (+/−3.7) in the MicroHip group. The dislocation rate was lower in the MicroHip group, being 1/216 compared with 3/55 in the traditional group. Harris Hip score for the MicroHip group was 91.35 at 3 months and 94.43 at 1 year. Average time for return to work was reduced from 8.2 to 2.7 weeks

Discussion: The results show that a truly minimal invasive approach improves the outcome of THR without additional risks. By the use of a treadmill incorporating a dynamic force plate there is even strong evidence that perception and therefore long term results can be improved.