Tantalum Cones Provide Durable Mid-term Fixation in Revision TKA.

BACKGROUND: Multiple studies have reported favorable short-term outcomes using tantalum cones to reconstruct massive bone defects during revision TKA. However, longer-term followup is needed to determine the durability of these reconstructions. QUESTIONS/PURPOSES: We wished to determine the mid-term (1) reoperation rates for septic and aseptic causes, (2) radiologic findings of osseointegration, and (3) clinical outcomes based on the Knee Society score in patients who underwent revision knee arthroplasty with tantalum cones for severe bone loss. METHODS: We retrospectively evaluated records of 18 patients (18 knees) who underwent revision knee arthroplasty with use of tantalum cones between 2005 and 2008; the primary indications for use of this approach were to reconstruct massive bone defects classified as Anderson Orthopaedic Research Institute Types 2B and 3. During this period, all defects of this type were treated with this approach and no cones were used for more-minor defects. A total of 26 cones (13 tibial and 13 femoral) were implanted. There were 12 female and six male patients with a mean age of 73 years (range, 55-84 years) at the time of revision. The indication for the revision included aseptic loosening (five patients) and second-stage reimplantation for deep infection (13 patients). Patients were followed for a mean of 6 years (range, 5-8 years). No patient was lost to followup. Clinical and radiographic outcomes were assessed with the Knee Society clinical rating system and radiographic evaluation system. RESULTS: There have been two reoperations for recurrent infection; at surgery, the two cones showed osseointegration. No evidence of loosening or migration of any implant was noted on the most recent radiographs. Knee Society knee scores improved from a mean of 31 points before surgery to 77 points at latest followup (p < 0.001), and function scores improved from a mean of 22 points to 65 points (p < 0.001). CONCLUSIONS: Tantalum cones for reconstruction of massive bone defects in revision knee arthroplasty provided secure fixation with excellent results at average followup of 6 years, although this series included relatively few patients. These devices are a viable option for surgeons to use in situations with severe bone loss. Further studies with longer followups are needed to confirm the durability of these reconstructions. LEVEL OF EVIDENCE: Level IV, therapeutic study.

Corrosion and Fretting of a Modular Hip System: A Retrieval Analysis of 60 Rejuvenate Stems.

Femoral stems with dual-taper modularity were introduced to allow independent control of length, offset, and version. Corrosion and fretting related to micromotion at the neck-stem junction are thought to stimulate an adverse local tissue reaction (ALTR). Analysis of 60 consecutively retrieved modular-neck stem implants (Rejuvenate, Stryker) revised primarily for ALTR was done to determine the variables influencing corrosion and fretting patterns at the neck-stem interface. Taper damage evaluation was performed with stereomicrocopic analysis with two observers. Evidence of fretting and corrosion was seen at the neck-stem taper in all implants, including three implants revised for periprosthetic fractures within four weeks of the index surgery indicating that this process starts early. Femoral stems paired with the long overall neck lengths had significantly higher corrosion scores. Correlation of the corrosion severity at particular locations with the length of implantation suggests that the neck-stem junction experiences cyclic cantilever bending in vivo. The positive correlation between the length of implantation and fretting/corrosion scores bodes poorly for patients who still have this implant. Scanning electron microscopy on a subset of specimens was also performed to evaluate the black corrosion material. We strongly urge frequent follow-up exams for every patient with this particular modular hip stem.

Primary total hip arthroplasty in severe developmental dysplasia of the hip. Ten-year results using a cementless modular stem.

We report the average 10-year clinical and radiographic results of 28 hips with Crowe III or IV developmental dysplasia of the hip (DDH) and a technically difficult primary hip arthroplasty using the cementless modular S-ROM stem (DePuy Orthopedics, Warsaw, Ind). Twenty-one patients required significant autologous bone grafting, 1 had a large allograft, and 6 patients required femoral shortening at the time of their total hip arthroplasty. Three patients had an intraoperative technical complication. The average preoperative Harris hip score was 37; at 10 years, 81. The Short Form 12 was 41.64 physical/54.03 mental at 10 years, and the WOMAC average score was 23 at 10 years. None of the S-ROM stems had been revised or were loose at latest follow-up. Six hips had osteolysis in Gruen zones 1 or 7 but none around or distal to the sleeve. The 10-year results of the S-ROM stem used in patients with osteoarthritis secondary to severe DDH are excellent.

Intraluminal acid induces oesophageal shortening via capsaicin-sensitive neurokinin neurons.

OBJECTIVE: Intraluminal acid evokes reflex contraction of oesophageal longitudinal smooth muscle (LSM) and consequent oesophageal shortening. This reflex may play a role in the pathophysiology of oesophageal pain syndromes and hiatus hernia formation. The aim of the current study was to elucidate further the mechanisms of acid-induced oesophageal shortening. DESIGN: Intraluminal acid perfusion of the intact opossum smooth muscle oesophagus was performed in vitro in the presence and absence of neural blockade and pharmacological antagonism of the neurokinin 2 receptor, while continuously recording changes in oesophageal axial length. In addition, the effect of these antagonists on the contractile response of LSM strips to the mast cell degranulating agent 48/80 was determined. Finally, immunohistochemistry was performed to look for evidence of LSM innervation by substance P/calcitonin gene-related peptide (CGRP)-containing axons. RESULTS: Intraluminal acid perfusion induced longitudinal axis shortening that was completely abolished by capsaicin desensitization, substance P desensitization, or the application of the neurokinin 2 receptor antagonist MEN10376. Compound 48/80 induced sustained contraction of LSM strips in a concentration-dependent fashion and this was associated with evidence of mast cell degranulation. The 48/80-induced LSM contraction was antagonized by capsaicin desensitization, substance P desensitization and MEN10376, but not tetrodotoxin. Immunohistochemistry revealed numerous substance P/CGRP-containing neurons innervating the LSM and within the mucosa. CONCLUSIONS: This study suggests that luminal acid activates a reflex pathway involving mast cell degranulation, activation of capsaicin-sensitive afferent neurons and the release of substance P or a related neurokinin, which evokes sustained contraction of the oesophageal LSM. This pathway may be a target for treatment of oesophageal pain syndromes.