Systemic Metal Ion Levels in Patients With Modular-Neck Stems: A Prospective Cohort Study.

BACKGROUND: Recent registry data reveal that modular-neck hip prostheses are associated with increased revision rates compared to fixed-neck stems. Poor implant survival has been associated to corrosion at the neck-stem junction, inducing metal ion release and subsequently adverse local tissue reactions. Data on metal ion release on the neck-stem junction of such stems are scarce. The purpose of this study was to evaluate corrosion at this interface by determining metal ion release. METHODS: Serum and whole blood metal ion levels of 40 patients after 1 year of implantation of a modular-neck stem (titanium stem and cobalt-chromium neck) were compared with 10 patients with a monobloc version of the stem (all titanium) and 10 patients having no implant at all. RESULTS: Seven of 40 patients (18%) with a modular-neck stem had cobalt or chromium concentrations >2 µg/L. These patients underwent magnetic resonance imaging using metal artifact reduction sequences, which revealed a pseudotumor in 1 patient. CONCLUSION: Corrosion at the neck-stem junction of modular-neck stems is a reported phenomenon, which is in part reflected by elevated systemic ion levels. The use of such implants should be restricted to a minimum, and screening algorithms of patients with such implants must be developed.

Comparisons of preoperative three-dimensional planning and surgical reconstruction in primary cementless total hip arthroplasty.

Reconstruction of important parameters such as femoral offset and torsion is inaccurate, when templating is based on plain x-rays. We evaluate intraoperative reproducibility of pre-operative CT-based 3D-templating in a consecutive series of 50 patients undergoing primary cementless THA through an anterior approach. Pre-operative planning was compared to a postoperative CT scan by image fusion. The implant size was correctly predicted in 100% of the stems, 94% of the cups and 88% of the heads (length). The difference between the planned and the postoperative leg length was 0.3 + 2.3 mm. Values for overall offset, femoral anteversion, cup inclination and anteversion were 1.4 mm ± 3.1, 0.6° ± 3.3°, -0.4° ± 5° and 6.9° ± 11.4°, respectively. This planning allows accurate implant size prediction. Stem position and cup inclination are accurately reproducible.

Long-term evaluation of the distal transverse plantar approach for Morton's neuroma excision.

BACKGROUND: There is currently no consensus on the ideal approach for the operative treatment of Morton’s neuroma. The distal transverse plantar approach aims at optimal exposure without the scar complications associated with the longitudinal plantar approach. Long-term evaluation based on validated outcome instruments is lacking. The main purpose of this retrospective study was to evaluate the long-term clinical outcome of this approach using validated function and scar evaluation scores. METHODS: Forty-nine patients operated on at our institution were examined clinically by two independent observers using the Foot and Ankle Ability Measure (FAAM) and the Vancouver Scar Scale (VSS). Patients who underwent neurectomy alone and those who had additional foot surgery were compared. RESULTS: Assessment at a mean of 7.9 years (range 4–12) postoperatively revealed a mean FAAM score of 84.8 ± 25% and a mean VSS score of 1.57 ± 1.7. Patients who underwent neurectomy alone had higher FAAM scores at follow up. We observed no complication that required an additional procedure. CONCLUSIONS: The transverse plantar approach results in good objective outcome scores, including scar healing, in the long term. This is our preferred technique because, in our experience, it offers optimal visualisation of the nerve, does not require deep dissection and allows the exposure of two adjacent web spaces of the foot through a single incision.