Porous tantalum stimulates the proliferation and osteogenesis of osteoblasts from elderly female patients.

Porous tantalum (Ta) implants have been successful in various orthopedic procedures for patients with compromised bone-forming abilities. Previous studies demonstrated that human osteoblast (HOB) cultures from older female patients produced less bone on implant materials in vitro compared to HOBs from age-matched male and younger female patients. In this study, the responses of HOBs from younger (< 45) and older (> 60 years old) female patients were compared on Ta, titanium fiber mesh (TFM) and tissue culture plastic. Adhesion, proliferation, and mineralization were greater in cells from younger patients than from older patients. Cell adhesion was slightly higher on Ta than TFM or plastic. However, Ta highly stimulated cell proliferation with a 4- and 6-fold increase compared to TFM for cells from younger and older patients, respectively, and 12- and 16-fold increase in proliferation compared to cells on plastic (p ≤ 0.001). At 3 weeks, mineralization was significantly higher on Ta compared to TFM for HOBs from older patients (p ≤ 0.05). Expression levels of bone matrix markers demonstrated differences dependent on age and substrate. Scanning electron micrographs revealed HOBs covering the surfaces and entering the pores of both Ta and TFM. In conclusion, tantalum greatly stimulates cell proliferation, and improves the ability of HOBs from older patients to form bone.

Implications for the anatomy of the flexor hallucis brevis insertion.

BACKGROUND: Excessive hallux proximal phalangeal base removal during first MTP resection arthroplasty, implant arthroplasty, or amputation can compromise the flexor hallucis brevis (FHB) insertion leading to first MTP joint plantarflexion weakness, cock-up toe deformity, and altered forefoot loading. MATERIAL AND METHODS: The insertional anatomy of the FHB tendon was measured in 30 fresh frozen cadaver specimens. The FHB was then cyclically loaded and bone sequentially removed from the proximal phalangeal base until specimen failure occurred. RESULTS: The mean length of the lateral and medial FHB insertions measured 9.0 +/- 0.6 mm and 8.0 +/- 0.5 mm, respectively (p < 0.0001). The mean width of the lateral and medial FHB insertions measured 7.1 +/- 1.0 mm and 8.8 +/- 1.4 mm, respectively (p < 0.0001). FHB insertion length as a percentage of total proximal phalangeal length was 26% +/- 3% medially and 30% +/- 3% laterally. Twenty-two specimens failed at the FHB insertion site after an average of 7.8 +/- 1.0 mm or 24% +/- 3% of the total length of the proximal phalanx had been resected from the base. CONCLUSION: Six millimeters of bone or 20% of the proximal phalangeal length could be safely removed from the hallux proximal phalangeal base without compromising the integrity of the FHB insertion to a physiologic load. Retaining 10 mm of the hallux proximal phalangeal base during amputation would preserve the medial FHB insertion and sacrifice none to less than 0.4 mm of the lateral insertion in our specimens. CLINICAL RELEVANCE: This study demonstrates how much hallux proximal phalangeal base can be resected during first MTP arthroplasty or needs to be retained during amputation to preserve FHB function.

Low body mass index: a risk factor for superior mesenteric artery syndrome in adolescents undergoing spinal fusion for scoliosis.

STUDY DESIGN: Five cases of superior mesenteric artery (SMA) syndrome occurred at our institution over a 4-year period in adolescents undergoing spinal fusion surgery for scoliosis. All patients had in common a very slender body habitus. The measurement of body mass index (BMI) was low in all patients and an age-matched control group of patients undergoing similar surgery without this complication was assessed with this Index to determine its utility as a screening tool for this postoperative condition. OBJECTIVE: The goal was to determine if BMI is a useful parameter to assess the relative risk of patients undergoing spinal fusion surgery for developing the complication of SMA syndrome. BACKGROUND DATA: SMA syndrome is a serious and potentially fatal complication of spinal fusion surgery for scoliosis. Significant curve correction and slender body habitus have been cited in the literature as potential risk factors for this disorder. METHODS: BMI and the amount of scoliosis curve correction in the 5 patients developing SMA syndrome after spinal fusion were calculated and compared with those values in a group of 18 age-matched patients undergoing spinal fusion during the same time period. RESULTS: Absolute curve correction was comparable between the 2 groups. All 5 patients who developed SMA syndrome had a BMI of less than 18. CONCLUSIONS: Patients undergoing spinal fusion surgery for scoliosis with a BMI of less than 18 are at risk to develop SMA syndrome postoperatively.

Management of hindfoot disease in rheumatoid arthritis.

There is a wide variety of hindfoot disease seen in patients with rheumatoid arthritis. Initial treatment is conservative including optimizing medical management to control the disease process. Should symptoms persist, surgical treatment may be performed, although there is an increased complication rate related to both the disease and the side effects of the medications used to treat it.