Astor Reigstad

Different patterns of bone fixation with hydroxyapatite and resorbable CaP coatings in the rabbit tibia at 6, 12, and 52 weeks†

Applying bioactive coatings on orthopedic implants can increase the fixation and long-term implant survival. In our study, we compared a resorbable electrochemically deposited calcium phosphate coating (Bonit®) to a thin (40 μm) plasma-sprayed hydroxyapatite (HA) coating, applied on grit-blasted screw-shaped Ti-6Al-4V implants in the cortical region of rabbit tibia, implanted for 6, 12, and 52 weeks. The removal torque results demonstrated stronger bone-to-implant fixation for the HA than Bonit-coated screws at 6 and 12 weeks. After 52 weeks, the fixation was in favor of the Bonit-coated screws, but the difference was statistically insignificant. Coat flaking and delamination of the HA with multinucleated giant cell activity and bone resorption observed histologically seemed to preclude any significant increase in fixation comparing the HA implants at 6 versus 12 weeks and 12 versus 52 weeks. The Bonit-coated implants exhibited increasing fixation from 6 to 12 weeks and from 12 to 52 weeks, and the coat was resorbed within 6 weeks, with minimal activity of multinucleated giant cells or bone resorption. A different fixation pattern was observed for the two coatings with a sharper but time limited increase in fixation for the HA-coated screws, and a slower but more steadily increasing fixation pattern for the Bonit-coated screws. The side effects were more serious for the HA coating and limiting the expected increase in fixation with time.

Long-term Results of Scaphoid Nonunion Surgery: 50 Patients Reviewed After 8 to 18 Years

Objectives: Untreated scaphoid nonunions are a hazard to the wrist, resulting in deteriorating function and radiologic degenerative changes with increasing time. Long-term results after surgery of scaphoid nonunion reporting clinical, radiologic, and subjective outcomes are scarce. Design: Retrospective follow-up study. Patients: From 1990 to 1998, 53 patients were operated on for persistent scaphoid nonunion; three patients were excluded from the follow-up (one expelled foreigner, another died of an unrelated cause, one never appeared after surgery), leaving 50 patients eligible for follow-up. Intervention: All patients were operated on with open reduction and internal fixation; the majority also received a bone graft. Main Outcome Measurements: Radiology and computed tomography verified union, degenerative wrist changes, and final salvage treatment. Range of motion, grip strength, key pinch, and subjective outcome (QuickDASH, visual analog scale). Results: Fifty patients were followed up after a mean of 12.2 years (standard deviation [SD], 3.0), 47 by clinical and radiologic examination; three were interviewed by telephone and completed QuickDASH and visual analog scale forms. Union was achieved in 45 of 50 scaphoids and an additional two after a second attempt. Five patients (one persistent and four healed nonunions) underwent salvage procedures. Grip strength (41 vs 45 kg, P = nonsignificant), key pinch (11.5 vs 12.4, P = nonsignificant), and active range of motion (186° vs 214°, P < 0.001) were slightly reduced compared with the uninjured side. The subjective outcome was good (mean visual analog scale = 7, mean QuickDASH = 9.1). Minor degenerative changes were seen in nine wrists at surgery and 22 at follow-up. Conclusion: Healing of a scaphoid nonunion provides long-term pain relief, excellent wrist function, and halts degenerative changes in the majority of patients. Level of Evidence: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Stem fracture with the Exeter prosthesis 3 of 27 hips followed for 10 years

We report the results of a 9-11-year clinical and radiographic follow-up of 27 Exeter prostheses in which cement pressurizing technique was employed. 3 stems fractured and 3 other stems and 1 cup underwent aseptic loosening. The remaining prostheses had satisfactory clinical and radiographic results. Stem subsidence was seen only as part of a loosening process. We suspect that the pronounced taper design is responsible for the poor results. While the slender and weak distal end is fixed in a thick cement mantle, the wide proximal part allows only a thin cement layer, easily subjected to mechanical disintegration. Proximal debonding increases both the stress on the distal part of the stem and the distal bone-cement interface shear stress. Hence, we believe that the same process underlies both the loosenings and the stem fractures. The presently employed Exeter stem is manufactured from the stronger Orthinox steel, which may diminish the risk for fracture, but it has retained the extreme taper design. It is not likely that a polished surface or improved cementing will prevent stem fracture. Therefore, one should still be concerned about late fractures of the Exeter stem.

SCAPHOID NON-UNIONS, WHERE DO THEY COME FROM? THE EPIDEMIOLOGY AND INITIAL PRESENTATION OF 270 SCAPHOID NON-UNIONS

Scaphoid injury and subsequent non-union is a well documented and researched subject. This article gives an overview of the epidemiology and results of the patients we have treated for scaphoid non-union at a University Hospital. 283 scaphoid non-unions in 268 patients (83% men) were operated upon, 230 as a primary and 47 as a secondary. The median age at time of surgery was 27 years. One-third of the non-unions were located in the proximal part of the scaphoid and the remaining two-thirds in the middle part. Of the 146 patients (55%) who contacted a doctor at the time of injury, 53 fractures where diagnosed (20%). Fourteen (5%) were operated primarily while 39 (15%) (seven dislocated) were immobilized in plaster casts. Thirty-two (12%) were under the age of 16 at the time of injury. The average time from the injury to the initial non-union surgery was 1.5 years with 2.8 years to the second procedure. The risk of osteoarthritis increased time from injury to surgery (both primary and secondary procedures). The greatest potential for the reduction of scaphoid non-union is an increased awareness amongst younger men. There is also potential for improved accuracy in the diagnosis of scaphoid fractures (better clinical tests, the use of radiographs, CTs and MRIs) in order to identify the fracture and evaluate dislocation at the initial injury. Early diagnosis and treatment of fractures and non-unions will reduce the development of degenerative wrist changes.

Femoral remodeling after arthroplasty of the hip: Prospective randomized 5-year comparison of 120 cemented/uncemented cases of arthrosis

We compared radiographically the femurs for 5 years after cemented (Landos Titane) and uncemented (Zweymüller/Endler) hip arthroplasty (THA) for coxarthrosis in 120 patients. The bone changes followed a characteristic time-course with rapid initial remodeling and almost no further changes after 3-4 years. No association between bone changes and clinical results was found. The groups did not differ in bone atrophy and ectopic bone formation, whereas the incidence of distal cortical hypertrophy and proximal radio-opaque double line was higher around uncemented stems. The age and body weight of the patients and the stem size did not affect the bone changes, but women with uncemented stems developed more bone atrophy than did men.

Supracondylar fractures with circulatory failure after reduction, pinning, and entrapment of the brachial artery: excellent results more than 1 year after open exploration and revascularization.

Objectives: Neurovascular injuries in children with dislocated supracondylar humeral fractures are not uncommon. Closed reduction and pin fixation usually will restore the circulation. In some patients, there is still compromised circulation and a neurologic deficit, and they are treated with open exploration and microvascular reconstruction. We have investigated the clinical and functional outcome more than 1 year after the injury in this most serious group of patients. Design: Retrospective follow-up study. Patients: During 2001 to 2007, five patients were referred to our department with a pale, pulseless hand and circulatory impairment with absent or slow capillary refill after primary treatment with closed reduction and cross pinning at their local hospital for Gartland Type III supracondylar fractures. Two of the patients also had clinical signs of nerve injury. Intervention: All were reoperated on with open exploration and release of the entrapped brachial artery. Vascular reconstruction was performed in four patients (vasodilating agent was sufficient in one patient) and release of the median nerve from the fracture in two. One of these two also had a Kirschner wire pierced through the ulnar nerve. All fractures were rereduced and cross-pinned. No intra- or postoperative complications were seen. Outcome/Results: At follow-up more than 1 year after the injury, all patients exhibited normal and symmetric function in their upper extremities, including circulation, neurologic status, range of motion, grip strength, and key pinch strength. Clinical and radiologic appearance was normal. Conclusion: Pulseless arms after repositioning of dislocated supracondylar humeral fractures are a medical emergency. After open release and, if necessary, microvascular reconstruction of vessels and nerves, fracture reduction, and fixation, excellent clinical long-term outcome can be expected. The procedure can be carried out with a low rate of complications.

Polyethylene wear with an entirely HA-coated total hip replacement : 79 hips followed for 5 years

We measured the eccentricity of the femoral head in the metal backing annually during 5 years in 79 consecutive total hip replacements (73 patients). The mean age of the patients was 57 (32-73) years and the female/male ratio 63/22. The prostheses were entirely coated with hydroxyapatite. Modular 32 mm stainless steel heads and hemispherical, self-tapping screw cups with polyethylene liners were used. We found accelerating eccentricity throughout the observation period. The mean eccentricity at 5 years was 0.71 mm (95% CI 0.53-0.90), resulting in a mean eccentricity rate of 0.14 mm (0.11-0.18) per year. The 5-year eccentricity was 0.5 mm or less in 45 hips and more than 1.5 mm in 13 hips, 2 in the latter group apparently having worn through the polyethylene liner. The true wear may be twice as great. The use of 32 mm stainless steel heads and thin polyethylene inlays may have aggravated the wear problems. These HA-coated prostheses must all be checked regularly, so that cases with excessive polyethylene wear can be reoperated on before wear-through of the liner.

Is revision bone grafting worthwhile after failed surgery for scaphoid nonunion? Minimum 8 year follow-up of 18 patients

Eighteen patients who underwent revision non-vascularized bone grafting and internal fixation after failed surgery for scaphoid nonunion were reviewed after a minimum of 8.2 years. Eleven of the nonunions were located in the middle and seven in the proximal third of the scaphoid. The mean interval between injury and the revision procedure was 6 years. Sixteen of the 18 nonunions healed, two after a third attempt. Three patients with healed nonunions and one patient with persistent nonunion required salvage procedures for progressive radiocarpal arthrosis. In the remaining 14 cases, the mean loss of wrist flexion/extension arc compared to the contralateral wrist was 36 °. Mean reduction of grip strength and key pinch was 9.3 kg and 0.9 kg respectively. The QuickDASH score was 18 and a visual analogue pain score was 21/100 at follow-up. Wrist degeneration increased in all but one case during the observation period. Thirteen of 16 patients with union and one patient with a persisting nonunion experienced moderate symptoms.

Free tissue transfer for type III tibial fractures : microsurgery in 19 cases

We report 19 tibial fractures Types III B and C treated by free flaps. The fracture healed in 16 cases after 12 (3-54) months. In 3 cases a secondary amputation was carried out. Tibial malalignment or substantial shortening ensued in 1 case each. We conclude that coverage with free flaps, radical removal of dead bone, stable external fixation and transfer of vascularized bone may salvage the majority of Type III B and C tibial fracture with function superior to that after amputation.

New concept for total wrist replacement

Abstract Wrist prostheses have never achieved the sort of clinical outcomes found with those of hips and knees. We have developed a novel uncemented modular wrist prosthesis with screw fixation, metal-on-metal coupling, and ball-and-socket articulation. Eight patients admitted for wrist arthrodesis to treat primary or secondary osteoarthritis (not rheumatoid) were operated on. The prosthesis reduced the amount of bone removed and spared the distal radioulnar joint. After 7 to 9 years we found that the fixed centre of the ball-and-socket articulation provided good stability and mobility, and relief of pain and grip strength were satisfactory. We saw no luxations, metacarpal fractures or cut-outs, or mechanical failures of the implants. Two distal screws loosened (revised with new distal screws), and one early inflammation and one late infection occurred (revised to arthrodesis). We propose modifications to the implant with reduction in the diameter of the screws and the height of the threads, and rounding of the distal tip. The technique should include release of the third carpometacarpal joint, alignment of the capitate and the third metacarpal, and arthrodesis of the joint with bone chips.