Magne Røkkum

HA particles can be released from well-fixed HA-coated stems: histopathology of biopsies from 20 hips 2-8 years after implantation.

20 hip arthroplasties with a Landos Corail Ti6Al4V stem entirely plasma-sprayed with a 155 - 35 w m thick HA coating were reoperated on after median 6 (2-8) years because of polyethylene wear (10), acetabular loosening (7), instability (2), or infection (1). We took biopsies from the proximal femurs adjacent to the well-fixed stems. Undecalcified sections were prepared and examined with a light microscope. The biopsies contained median 5 (1.3-16 ) mm metal interface with 54% HA, 32% bone, and 14% soft tissue. The median thickness of the remaining HA coating was 137 (6-380) w m, and the HA-tissue interface included 89% bone and 11% soft tissue. All HA coatings showed partial degradation and replacement by soft tissue, osteoid-like tissue, or bone. 6 hips had tissue ingrowth between HA and metal consistent with delamination. 14 hips showed bone resorptive areas containing some HA particles and large amounts of polyethylene and metal particles, partly internalized in multinucleated giant cells and macrophages. Bone resorption was associated with metal and polyethylene particles, but not with HA particles. The HA coatings were undermined, resulting in release of large flakes of HA with free access to the articulation. We believe this mechanism may be responsible for third-body wear.

Polyethylene wear, osteolysis and acetabular loosening with an HA-coated hip prosthesis A FOLLOW-UP OF 94 CONSECUTIVE ARTHROPLASTIES

We have followed up for a period of seven to nine years 100 consecutive arthroplasties of the hip in which an entirely HA-coated implant had been used. The clinical results were excellent and bony incorporation was extensive in all components. No stem became loose or subsided but five cups were revised because of loosening after 3.8 to 5.5 years, having functioned painlessly and shown radiological ingrowth. Revision procedures because of excessive polyethylene wear have been performed on 18 hips and are planned for six more. Two eroded metal backings with worn-through polyethylene were exchanged; six hips showed metallosis without polyethylene wear-through. There were two cases of granulomatous cysts in the groin and 66 hips had osteolysis located periarticularly, in the greater trochanter or in the acetabulum.

Excellent long-term survival of an uncemented press-fit stem and screw cup in young patients: Follow-up of 75 hips for 15–18 years

Background The long-term results of uncemented total hip arthroplasties vary widely due to differences in design, metal alloy, coating, surface structure, and porosity. Patients and methods We retrospectively studied 75 cementless Zweymüller SL stems in combination with Endler titanium-backed threaded cups (Z-E) in 70 patients. 35 patients were women, and the mean age at surgery was 52 (24–68) years. 16 patients died and 1 emigrated, 7 patients (of which 1 later died) subsequently underwent revision, and the remaining 47 patients with 50 original arthroplasties were followed up after a median of 16 (15–18) years. Results Revision of 8 hips resulted in an 18-year Kaplan-Meier estimated overall survival rate of 88% (CI: 79–96). 6 of 7 cup revisions were due to liner wear and osteolysis, and 1 was due to aseptic loosening. 2 of 3 stem revisions were due to femoral loosening and 1 was due to fracture of the neck of the stem. The clinical results were good, with a mean Harris hip score of 89 (54–100). Half of 70 hips in 65 patients had ectopic bone formation. All unrevised implants were radiographically stable, with a mean liner wear of 0.07 mm/year. Interpretation These long-term results demonstrate that the combination of a Zweymüller SL stem and an Endler titanium-backed screw cup is a good hip arthroplasty in young and active patients. A prefixed polyethylene liner is a drawback, necessitating exchange of the whole cup in cases with polyethylene wear.

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.

Cold Hypersensitivity 6 To 10 Years after Replantation or Revascularisation of Fingers: Consequences for Work and Leisure Activities

We investigated cold hypersensitivity and activity in 81 adults (male/female 76/5), 6 to 10 years after finger replantation/revascularisation (mean age at injury 43 (SD 15) years). Questionnaires included the McCabe Cold Sensitivity Severity Scale, Potential Work-Exposure Scale and the Disabilities of the Arm, Shoulder and Hand (DASH) score. Eighty per cent of the respondents were cold hypersensitive; 20% were severely or extremely cold hypersensitive. Of the 74 patients employed at injury, 7% had changed work and 4% were not working due to cold hypersensitivity. The median score for cold exposure at work at follow-up was 153 (scale 0–300). The correlation between cold sensitivity and DASH work was low. One-third of the respondents experienced limitations in their leisure activities because of cold complaints. Long-term cold sensitivity was mild or moderate for most patients. Many cold hypersensitive patients managed to continue to work even under cold conditions and cold hypersensitivity was a greater problem in leisure activities.

Tissue reactions adjacent to well-fixed hydroxyapatite-coated acetabular cups. Histopathology of ten specimens retrieved at reoperation after 0.3 to 5.8 years.

Ten acetabular cups coated with hydroxyapatite (HA) had originally been inserted in five primary and five revision total hip replacements. The thickness of the HA was 155 +/- 35 microm. The cups, which were well-fixed, were retrieved, with their adherent tissue, at reoperation after 0.3 to 5.8 years because of infection (five hips), wear of polyethylene (three hips), and instability (two hips). Undecalcified sections showed a direct contact between bone and osteoid-like tissue which had formed directly onto the HA coating. The area within the threads and their mirror images, as well as the implant-tissue interfaces consisted of similar amounts of bone and soft tissue. Degradation of HA was seen in all hips. The mean thickness of the remaining HA coating was 97 microm (95% CI 94 to 101). The metal interface comprised 66% HA. The HA-tissue interface contained more bone than soft tissue (p = 0.001), whereas the metal-tissue interface included more soft tissue than bone (p = 0.019). Soft tissue at the implant interface and poor replacement of HA by bone may interfere with long-term fixation.

Predictors of outcome after primary flexor tendon repair in zone 1, 2 and 3:

We retrospectively reviewed the outcomes of flexor tendon repairs in zones 1, 2 and 3 in 356 fingers in 291 patients between 2005 and 2010. The mean (standard deviation) active ranges of motion of two interphalangeal joints of the fingers were 98° (40) and 114° (45) at 8 weeks postoperatively and at the last follow-up (mean 7 months, range 3–98), respectively. Using the Strickland criteria, ‘excellent’ or ‘good’ function was obtained in 95 (30%) out of 322 fingers at 8 weeks and 107 (48%) out of 225 fingers at the last follow-up. A total of 48 (13%) fingers required reoperation because of rupture, adhesion, contracture or other complications. The prevalence of rupture was 4%. We carried out multiple linear regression analysis to identify the predictors of the active digital motion. The following variables were found as negative predictors: age; smoking; injury localization between subzones 1C and 2C; injury to the little finger; the extent of soft tissue damage; concomitant skeletal injury; delay to surgery; use of a 2-strand Kessler repair technique; attempted suture or preservation of the tendon sheath–pulley system; and resecting or leaving the concomitant superficial flexor tendon cuts untreated. Analysing the 8 weeks results of tendon repairs in zones 1 and 2, early active mobilization was found to be superior to Kleinert’s regime. Level of evidence: III

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.