Migration pattern of a short femoral neck preserving stem.

UNLABELLED: The CFP stem represents a short collared neck-retaining stem with very proximal metaphyseal anchoring along the calcar combined with up-to-date metallurgy. Despite theoretical advantages, the stability and clinical outcome are unknown. We prospectively measured the migration pattern of this new stem and cup. Twenty-six patients (26 hips) with a mean age of 54 years (range, 40-66 years) underwent THA and were followed for 2 years with radiostereometry, radiographs, and clinical scores. The stem showed some early retroversion (mean, SEM 0.6 degrees, 0.3), but stabilized before 1 year. Subsidence (0.05 mm, 0.06) and varus-valgus tilting (0.03 degrees, 0.01) were low. We observed no bone loss in the calcar region. Factors related to patients, implant design, and implantation did not predict migration patterns. The two-dimensional wear of the ceramic/conventional articulation was 0.09 mm at 2-24 months. The low migration of this short neck preserving stem suggests a favorable long-term outcome but longer followup is needed to substantiate this prediction. This design might become an alternative to standard stems and hip resurfacing. LEVEL OF EVIDENCE: Therapeutic Level IV. See The Guidelines for Authors for a complete description of levels of evidence.

Impacted corticocancellous allografts and cement for revision of the femur component in total hip arthroplasty.

Revision of the femur component in total hip arthroplasty using impacted morcellized bone allografts and cemented Lubinus SP-II prosthesis or Charnley standard prosthesis was performed in patients with loss of bone stock grade II through IV according to the Endo-Klinik classification from 1st to 8th revision. We report the results from 57 hips in 56 patients, with a median of 64 months' follow-up. Modified Merle d'Aubigne-Postel postoperative scores increased significantly from preoperative to postoperative values for the Lubinus group and for the Charnley group. Few complications were seen in this follow-up period. Five stems had minor subsidence. Rate of mechanical failure was 4% for both groups. Radiologic examinations provided evidence of frequent trabecular remodeling of the graft, especially for the Lubinus prosthesis.

Histology of impacted bone-graft incorporation.

We describe the histologic findings of 31 tissue samples from 21 cases in 19 different patients taken 1 to 48 months after revision arthroplasty and impaction grafting in the hip (Lubinus SP-II prosthesis Waldemar Link, Hamburg, Germany, or Charnley Elite prosthesis, Johnson & Johnson, New Brunswick, NJ) and the knee (Link Rotation Knee Waldemar Link). One month after surgery, a fibrous stroma and some newly formed woven bone were found in the graft bed. After 4 months, many of the dead trabeculae in the graft bed had layers of living bone and osteoid in all samples. These layers, indicating a gradual ingrowth of living bone, increased over time. In the proximal end of the femur examined after 48 months, a significant proportion of the graft bone remained dead, whereas in the rest of the femur, the bone healing was complete. A similar but possibly less frequent bone formation was found in the 2 cases evaluated after a revision total knee arthroplasty combined with impaction grafting.

Bigger size and defatting of bone chips will increase cup stability.

Morcellised bone allograft in an in vitro model was used to test the tendency towards cup rotation using small or larger fragment sizes of an impacted graft bed and different fat contents. A cup cemented on an impacted graft bed of larger sized bone chips from the Howex bone mill containing natural marrow fat was loaded eccentrically until the cup rotated. This required 3450 N. The same chips impacted in the same way, but defatted with warm saline solution required 7000 N for rotation. The smaller sized bone chips from the Tracer bone mill defatted in a similar manner required only 1950 N for cup rotation. The conclusion was that larger sized chips, partly defatted, prevent rotation of a cup cemented on a graft bed.

Reduced bleeding through temporary balloon occlusion in hip and knee revision surgery.

We used temporary balloon occlusion of the iliac or femoral artery to reduce blood loss in major hip or knee operations in 15 cases in 13 patients. The balloon was introduced by an interventional radiologist in the afternoon of the day before surgery or in the morning before. A latex occlusion balloon was inserted via the transfemoral ipsi- or contralateral route. The patients received two 40 mg doses of low molecular weight heparin. At the beginning of the operation, saline was injected into the predetermined volume to inflate the balloon. The balloons were inflated during 1-6 hours. In each case, the balloon occlusion clearly reduced bleeding in the surgical field and facilitated surgery. The perioperative bleeding was reduced by half, as compared to a retrospective control group. We measured the intraarterial blood pressures distally to the balloon in 2 patients. They decreased from 120 to 40 mm Hg and 155 to 50 mm Hg, respectively, after inflation. Two complications occurred, one bleeding due to catheter dislocation the night before surgery and one postoperative necrosis of the tip of a toe in a patient in whom the deflated balloon was not extruded until the day after surgery and the dose of heparin was too low.

Impacted corticocancellous allografts: recoil and strength.

Bone allografts were morcellized using 2 different milling machines (Tracer milling machine and Howex milling machine) producing bone chips with different ranges of sizes. In an in vitro model, each type of bone-graft was impacted with 2 different impaction forces. As the impaction force was released, there was a substantial and rapid recoil of the graft bed. More recoil was seen with the smaller chips and with the harder impacted graft beds. Most of the recoil occurred within the first 10 seconds. Using another similar in vitro model, the same 2 kinds of chips were impacted with 2 different impaction forces, and the subsidence of the 4 different graft beds was measured. There was less subsidence with the bigger type of bone chips and less with the harder impacted graft beds.

Histology of the femur after cancellous impaction grafting using a Charnley prosthesis.

We report the histologic findings of a retrieved femur 6 months after a cemented hip revision with a Charnley standard prosthesis and impaction of morselized allograft. Most transplanted areas were revascularised. In the proximal femur there was new bone formation peripherally, but a substantial amount of fibrous stroma embedding graft pieces closer to the cement. In the diaphysis new bone formation had proceeded to within less than 0.5 mm of the cement.

Impacted morsellized allograft and cement for revision total knee arthroplasty: a preliminary report of 3 cases.

In 3 cases we have revised a failed knee arthroplasty with intramedullary impaction of morsellized allograft similar to the technique described for the hip. Follow-up after 18, 21 and 28 months showed good clinical and radiographic results.

Fixation of femoral neck fracture. Prospective comparison of von Bahr screws, Gouffon screws, and Hessel pins.

We report a prospective study of 214 patients with femoral neck fractures operated on with multiple pinning. The fractures were randomly allocated to fixation with either von Bahr screws or Hessel pins in 1983 and 1984 or von Bahr or Gouffon screws in 1984 and 1985. After 2 years, the failure rate was one third in the von Bahr and the Gouffon screw groups and one half in the Hessel pin group. We conclude that the nonthreaded Hessel pin is inferior to the von Bahr and Gouffon screws for fixation of femoral neck fractures.