Hip revision arthroplasty in periprosthetic fractures of vancouver type B2 and B3.

OBJECTIVES: The purpose of the study was to test the hypothesis that stem revision in Vancouver Type B2 and B3 periprosthetic fractures using a transfemoral surgical approach and a modular, noncemented, tapered and fluted revision stem led to reproducibly good results with respect to fracture healing, stability of the prosthesis stem, dislocation, intraoperative fracture, and clinical outcome. DESIGN: Prospective study. SETTING: Orthopaedic specialized clinic and center for joint replacement. PATIENTS: Twenty-two patients with periprosthetic fractures of Vancouver Type B2 and 10 of Type B3 were followed of at least 24 months. MAIN OUTCOME MEASURE: Fracture healing, stability of the prosthesis stem, complications, and clinical outcome. RESULTS: All fractures healed with a mean time of 14.5 ± 5.2 weeks. No cases of subsidence of the stem were observed and, according to the classification of Engh et al concerning the biologic fixation of the stem, there was bony ingrowth fixation in 28 cases and stable fibrous fixation in four cases. One dislocation occurred and there were no cases of intraoperative fracture. The Harris hip score rose continually after the operations; from a score 3-months postoperatively of 59.2 ± 14.6 points, it rose to 81.6 ± 16.5 points after 24 months. According to the classification of Beals and Tower, all results were rated as excellent. CONCLUSIONS: The methods described here for stem revision lead to reproducibly good results in the treatment of periprosthetic hip fractures of Vancouver Types B2 and B3. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Bone regeneration in the proximal femur following implantation of modular revision stems with distal fixation.

INTRODUCTION: A quantitative analysis of the response of proximal femur bone to implantation of revision stems with distal fixation and of the factors that affect that response has not previously been published. MATERIALS AND METHODS: A prospective study of 138 stem revision operations involving replacement with cementless, modular, titanium revision stems with distal fixation (Revitan, Zimmer GmbH, Winterthur, Switzerland) was designed to assess Barnett and Nordin scores at the proximal femur obtained immediately after surgery and at a 3-year follow-up examination in order to analyze bone regeneration in the proximal femur and associated response-modifying factors. RESULTS: In general, a bone formation with increase of the Barnett and Nordin score was observed. However, stress shielding occurred in cases of osteoporosis or more severe bone defects. A statistical analysis of possible factors that might affect the bone response revealed that the degree of bone regeneration was directly related to the Barnett and Nordin score obtained immediately post-surgery and the severity of the bone defect and only indirectly to the length of the stem, which is determined by the type of bone defect, and to the necessity of interlocking screws. CONCLUSION: Distally fixed titanium revision stems do not result in stress shielding per se. Proximal bone response depends mostly on the condition of the bone before and immediately after the operation and not, as stated in many reports, on surgical procedures such as method of approach or the thickness of the prosthesis.

[Exchange of acetabular cups with severe bone defects using antiprotrusion cages]. / Pfannenwechsel bei grösseren Defekten mit Antiprotrusionsringen.

OBJECTIVE: Replacement of a loosened acetabular cup attended by massive bone defects involving both columns. Acetabular restoration and proof fixation of a new acetabular cup to restore a pain-free joint function. INDICATIONS: Segmental acetabular bone defects involving both columns (Paprosky type 3A, 3B) with loosened acetabular cup or a Girdlestone situation. In case of pelvic discontinuity (Paprosky type 4) combination with reconstructive osteosynthesis plates (for example, Synthes company, Bochum, Germany). CONTRAINDICATIONS: In cases of complete absence of the posterior and especially cranioposterior column combination with structural allograft reconstruction necessary. Relative: acetabular defects, that can be reconstructed by other, smaller implants, for example, press-fit acetabular cups. SURGICAL TECHNIQUE: Exposure of the acetabulum by a conventional approach. Removal of the loosened acetabular cup. Cleaning of the acetabulum with a sharp spoon. Rebuilding of the hip center with a reamer. Choice of the size of the antiprotrusion ring using trial implants. Access chiseling for the inferior implant flange into the ischium. If necessary, adaptation of the superior and inferior flange alignment to the individual anatomy by bending. Filling of bone defects with allogenic bone chips. Knocking in of the inferior flange into the ischium. Simultaneous knocking in of both the ring in the acetabulum and the superior flange at the ischium. Screwing in of bolts from the interior of the ring into the iliac bone in the direction of hip forces. Additional positioning of screws due to the superior flange into the iliac bone. Cementing in of a polyethylene cup in the antiprotrusion ring. POSTOPERATIVE MANAGEMENT: Antithrombotic prophylaxis, physical therapy, gait training under full weight bearing of the limb. RESULTS: 30 acetabular cup revisions with a new Burch-Schneider ring underwent prospective clinical and radiologic examination and were analyzed for an average follow-up of 20.6+/-7.8 months (3-36 months). The Harris Hip Score increased from preoperative 46.6 to postoperative 75.9 points. A loosening of the cage was not recorded.

Distal interlocking screws with a modular revision stem for revision total hip arthroplasty in severe bone defects.

A prospective study of 15 patients was designed to examine whether the modular cementless revision stem (Revitan curved; Zimmer GmbH, Winterthur, Switzerland) is suitable for stem revisions with a defective isthmus when distal interlocking screws are also used for fixation. During a follow-up period of 35.4 +/- 11.4 months (24-70 months), there was one stem loosening with screw breakage in a case of a stem that was too thin. According to Engh et al, bony ingrowth fixation of the stem occurred in 12 cases and stable fibrous fixation in 2 cases. The Harris Hip Score rose continuously from 44.7 +/- 12.9 points preoperatively to 75 +/- 10 points at 24 months. This concept of additional stem fixation with distal interlocking screws represents a useful treatment option for revision arthroplasty in rare cases of a defective isthmus.

Two-stage cementless revision of infected hip endoprostheses.

UNLABELLED: Cementless two-stage revision of infected total hip prostheses lacks the possibility of local antibiotic protection of the implant at the time of reimplantation, which leads to the concern that this protocol may not sufficiently eradicate periprosthetic infection. Moreover, early implant loosening as much as 18% and stem subsidence as much as 30% have been reported. To determine whether a cementless revision could eradicate infection and achieve sufficient implant stability, we prospectively followed 36 patients with two-stage revisions for septic hip prostheses. We used a uniform protocol of a 6-week spacer interval, specific local and systemic antibiotic therapies, and cementless modular revision stems. The minimum followup was 24 months (mean, 35 months; range, 24-60 months). In one patient, the spacer was changed when the C-reactive protein value failed to normalize after 6 weeks, and the reimplantation was performed after an additional 6 weeks. No infections recurred. There was no implant loosening and a 94% bone-ingrowth fixation of stems. Subsidence occurred in two patients. The Harris hip score increased from a preoperative mean of 41 to 90 at 12 months after reimplantation and later. Using cementless prostheses in two-stage revisions of periprosthetic infections of the hip in combination with a specific local and systemic antibiotic therapy seems to eradicate infection and provide implant stability. LEVEL OF EVIDENCE: Level IV, therapeutic study.

Short-term results of hip revisions with a curved cementless modular stem in association with the surgical approach.

INTRODUCTION: A prospective study was designed to test the hypothesis that short-term results after hip revisions are in association with the surgical approach with lower clinical scores for the transfemoral approach. MATERIALS AND METHODS: A total of 120 hip revision operations with the modular cementless revision stem "Revitan Curved" (Zimmer GmbH, Winterthur, Switzerland), of which 42 replacements involved an endofemoral (posterolateral) approach and 78 implantations a transfemoral approach, were followed up over a period of at least 24 months. RESULTS: In the early post-operative stage, stems implanted transfemoral were associated with significantly lower Harris Hip Scores and a significantly more frequent appearance of Trendelenburg signs. The differences lessened at the end of the follow-up period. Within the group of transfemoral implantation, all six stems with a circular fixation zone measuring less than 3 cm had subsided and two of these had become loose; none of the stems with greater fixation zones exhibited these properties. In the case of the endofemoral implants, three stems exhibited sinking but there did not appear to be any relationship between this event and length of fixation zone. CONCLUSION: The surgical approach has an association with the short-time outcomes of hip revsions using cementless modular stems. Transfemoral implantation of the "Revitan curved" stem requires a fixation zone of at least 3 cm and a longer period of rehabilitation.

[Technique of implantation of a cementless press-fit cup in revisions with severe bone defects]. / Technik der Implantation einer zementlosen Pressfit-Pfanne bei Pfannenrevisionen mit grösseren Knochendefekten.

OBJECTIVE: Revision of loose cups of total hip arthroplasties. Implantation and solid fixation of a cementless press-fit cup to restore painless joint function. INDICATIONS: Loose cups of total hip arthroplasties. Reimplantation of a prosthetic cup after removal of an infected total hip arthroplasty. CONTRAINDICATIONS: Bone defects of the acetabulum precluding a press-fit fixation (at least three-surface fixation) of the cup. Persistent infection. SURGICAL TECHNIQUE: Exposure of the acetabulum using a standard approach. Removal of the loose cup. Cleaning of the ground with a spoon. Reaming of a new, deeper center of rotation in the acetabulum using a small reamer. Stepwise reaming of the acetabulum using increasing reamer sizes without pressure until sufficient bone contact at the rim is reached (at least three-surface fixation). Hammering in of a thin-walled cementless press-fit cup (e.g., AllofitStrade mark) of the next size as compared to the reamer chosen last to reach a 4-mm press-fit fixation. Additional screwing in of two to three cancellous screws into the os ilium. POSTOPERATIVE MANAGEMENT: Thrombosis prophylaxis, physiotherapy, gait training with partial loading of the limb at 10 kg for a period of 6 weeks. Then increased loading by 10 kg per week. RESULTS: 52 cup exchanges using an AllofitStrade mark cup were clinically and radiologically analyzed over an average period of 35.8 +/- 8.8 months (26-53 months). The Harris Hip Score increased from a preoperative value of 46.4 to 87.3 points 2 years postoperatively. Two cups showed migration and one hip dislocated. Loosening has not been observed so far.

A modified transfemoral approach using modular cementless revision stems.

The transfemoral approach in its traditional form, using a nonmodular Wagner self-locking revision stem, has the disadvantages of a less predictable union rate of the bony flap and a high rate of stem subsidence. To investigate whether this situation can be improved by using a modified transfemoral approach and modular curved cementless revision stems, we prospectively analyzed 68 hip revisions and followed them clinically and radiographically for a minimum of 24 months (mean +/- standard deviation, 32.4 +/- 11.2 months). One year after the operation, the osteotomy showed bony consolidation in all but one case (98.5%). We noted subsidence in six cases (8.8%) and two of these stems became loose. In all of these cases, the circular fixation zone of the stem in the isthmus of the femur was less than 3 cm. The Harris hip score improved continuously from 41.4 +/- 14.5 points preoperatively to 85.9 +/- 14.6 points 24 months postoperatively. The modified transfemoral approach in combination with a curved, modular revision stem showed reproducibly good results concerning union of the bony flap and subsidence of the stem if the fixation zone was not less than 3 cm.

Modified transfemoral approach to revision arthroplasty with uncemented modular revision stems.

OBJECTIVE: Removal of a loose or fractured stem in total hip arthroplasty. Implantation and secure fixation of a modular uncemented revision stem to restore painless joint function. INDICATIONS: Loose and/or broken prosthetic stem. Risk of intraoperative fracture or perforation of the femur when stem revision becomes unavoidable. Periprosthetic fracture. CONTRAINDICATIONS: Loose prosthetic stems that can be revised without the risk of perforation or fracture of the femur. Interprosthetic femoral fractures between the ends of hip and knee prosthetic stems that require total replacement of the femur. SURGICAL TECHNIQUE: Exposure of the femur anterior to the lateral lip of the linea aspera in the lateral intermuscular septum. 3.2-mm drill holes are made at the anterior and posterior ends of the planned bone flap. Osteotomy of the femur anterior to the junction of the vastus lateralis and the gluteus medius muscles. Posterior osteotomy as well as distal transverse osteotomy between the drill holes and distal anterior osteotomy. The anterior osteotomy is performed using a chisel passed under the vastus lateralis from distal to proximal at the anterior aspect. The osteotomized lateral femoral bone flap with muscle attachment is folded back. Implantation of a modular uncemented revision stem and fixation of the bone flap with double cerclage. POSTOPERATIVE MANAGEMENT: Thrombosis prophylaxis, physiotherapy, gait training with partial loading of the limb at 10 kg for a period of 6 weeks with hip flexion limited to 70 degrees. Then, free range of movement and increased loading by 10 kg per week. RESULTS: 74 modular uncemented revision stems were implanted in transfemoral technique and the outcomes clinically and radiologically analyzed over an average follow-up period of 20.2 +/- 12.1 months (10-43 months). The Harris Hip Score increased from a preoperative value of 42.21 to 85.97 points after 2 years. Subsidence was observed for four stems and early loosening for two stems. The press-fit anchorage of these latter two stems was < 3 cm.