Two-centre radiological survivorship of acetabular distraction technique for treatment of chronic pelvic discontinuity: mean five-year follow-up.

Aims The aim of this study was to examine the results of the acetabular distraction technique in achieving implantation of a stable construct, obtaining biological fixation, and producing healing of chronic pelvic discontinuity at revision total hip arthroplasty. Patients and Methods We identified 32 patients treated between 2006 and 2013 who underwent acetabular revision for a chronic pelvic discontinuity using acetabular distraction, and who were radiographically evaluated at a mean of 62 months (25 to 160). Of these patients, 28 (87.5%) were female. The mean age at the time of revision was 67 years (44 to 86). The patients represented a continuous series drawn from two institutions that adhered to an identical operative technique. Results Of the 32 patients, one patient required a revision for aseptic loosening, two patients had evidence of radiographic loosening but were not revised, and three patients had migration of the acetabular component into a more stable configuration. Radiographically, 22 (69%) of the cohort demonstrated healing of the discontinuity. The Kaplan-Meier construct survivorship was 83.3% when using revision for aseptic acetabular loosening as an endpoint. At the time when one patient failed due to aseptic loosening (at 7.4 years), there were a total of seven patients with a follow-up of seven years or longer who were at risk of failure. Conclusion The acetabular distraction technique demonstrates encouraging radiographic outcomes, with healing of the discontinuity in over two-thirds of our series. This surgical technique permits biological fixation and intraoperative customization of the construct to be implanted based on the pattern of the bone loss identified following component removal. Cite this article: Bone Joint J 2018;100-B:909-14.

Evaluation and management of chronic total hip instability.

Given the increasing number of total hip arthroplasty procedures being performed annually, it is imperative that orthopaedic surgeons understand factors responsible for instability. In order to treat this potentially complex problem, we recommend correctly classifying the type of instability present based on component position, abductor function, impingement, and polyethylene wear. Correct classification allows the treating surgeon to choose the appropriate revision option that ultimately will allow for the best potential outcome.

Treatment of pelvic osteolysis associated with a stable acetabular component inserted without cement as part of a total hip replacement.

Thirty-five patients who had had a primary total hip replacement with a porous-coated acetabular component inserted without cement had a revision procedure to treat pelvic osteolysis. The mean age at the time of the revision operation was forty-nine years (range, twenty-nine to eighty-five years). Forty-six distinct pelvic osteolytic lesions were noted radiographically around the thirty-five cups. These lesions ranged in size from 0.5 by 0.5 centimeter to 6.3 by 2.7 centimeters (mean, 2.6 by 1.7 centimeters). Fourteen of the thirty-five patients had no or only slight occasional pain at the time of diagnosis of the pelvic osteolysis, fifteen patients had pain attributed to a loose femoral component, one had pain related to a spontaneous fracture of the greater trochanter, and one had pain related to recurrent subluxation. The remaining four patients had pain in the groin despite radiographically stable implants. All of the metal-backed porous-coated acetabular components were stable according to the preoperative radiographs, and the stability was confirmed at the time of the revision. The metal shell was left in place and the acetabular liner was exchanged in all thirty-five patients. The osteolytic lesions were debrided, and thirty-four of the forty-six lesions were filled with allograft bone chips. The patients were evaluated a minimum of two years (range, two to five years; mean, 3.3 years) after the revision operation, and all thirty-five sockets were found to be radiographically stable. The bone grafts appeared to have consolidated, and none of the osteolytic defects had progressed. One-third of the lesions were no longer visible on radiographs, regardless of whether or not they had been filled with bone graft. The remaining lesions had decreased in size. It appears that, in the short-term, exchange of the liner and debridement of the granuloma, with or without use of allograft bone chips in the osteolytic defect, is a reasonable alternative to revision of the socket provided that the metal shell is solidly fixed at the time of the revision operation. If the metal shell has been markedly damaged by the femoral head, the locking mechanism for the polyethylene liner is not intact, or a satisfactory replacement liner is not available, then revision of the porous-coated acetabular component is indicated. These results must be considered preliminary. Since osteolysis may take several years to redevelop after a revision, additional follow-up is required.

High rate of failure of allograft reconstruction of the extensor mechanism after total knee arthroplasty.

BACKGROUND: Disruption of the extensor mechanism is an uncommon but devastating complication of total knee arthroplasty. Several techniques for reconstruction of the extensor mechanism after total knee arthroplasty have been reported, but we do not know of any study in which the results of one group's method were corroborated by a second group using the same technique. In the present series, we evaluated the results of reconstruction of the extensor mechanism with use of allograft according to the method described by Emerson et al. METHODS: Seven reconstructions of the extensor mechanism with use of a bone-tendon-bone allograft were performed with the technique of Emerson et al. in six patients. The patients were evaluated before and after the operation. The knee score according to the system of The Hospital for Special Surgery, evidence of an extensor lag, use of walking aids, and the ambulatory status of each patient were recorded. The patients were also asked about, and the medical records were reviewed for, episodes of falling related to weakness of the quadriceps after the reconstruction. The mean duration of follow-up was thirty-nine months (range, six to 115 months). As these reconstructions often fail early, the minimum duration of follow-up was six months. RESULTS: All seven reconstructions were rated as clinical failures on the basis of a persistent or recurrent extensor lag of more than 30 degrees. All but one patient needed an assistive device full time for walking, and four patients (five knees) had at least one documented episode of falling that was due to giving-way of the affected knee. Four of the reconstructions were revised; one revision was performed with use of another extensor mechanism allograft and three were performed with use of a medial gastrocnemius rotation flap. The other three clinical failures had not been revised at the time of writing. At the time of the most recent follow-up (or at the time of revision of the extensor reconstruction), the mean extensor lag was 59 degrees and the mean knee score was 52 points (a poor result). CONCLUSIONS: Undertensioning of the allograft reconstruction at the time of the operation and attenuation of the allograft both may have played a role in the inability of the patients to regain active extension of the knee postoperatively. Alternative techniques for reconstruction of the extensor mechanism or modifications of this technique should be considered in the treatment of this difficult problem.

Metal release in patients who have had a primary total hip arthroplasty. A prospective, controlled, longitudinal study.

UNLABELLED: There is an increasing recognition that, in the long term, total joint replacement may be associated with adverse local and remote tissue responses that are mediated by the degradation products of prosthetic materials. Particular interest has centered on the metal-degradation products of total joint replacements because of the known toxicities of the metal elements that make up the alloys used in the implants. We measured the concentrations of titanium, aluminum, cobalt, and chromium in the serum and the concentration of chromium in the urine of seventy-five patients during a three-year prospective, longitudinal study. Twenty patients had had a so-called hybrid total hip replacement (insertion of a modular cobalt-alloy femoral stem and head with cement and a titanium acetabular cup without cement), fifteen had had insertion of an extensively porous-coated cobalt-alloy stem with a cobalt-alloy head and a titanium-alloy socket without cement, and twenty had had insertion of a proximally porous-coated titanium-alloy stem with a cobalt-alloy head and a titanium socket without cement. The remaining twenty patients did not have an implant and served as controls. The results of our study showed that, thirty-six months postoperatively, patients who have a well functioning prosthesis with components containing titanium have as much as a threefold increase in the concentration of titanium in the serum and those who have a well functioning prosthesis with cobalt-alloy components have as much as a fivefold and an eightfold increase in the concentrations of chromium in the serum and urine, respectively. The predominant source of the disseminated chromium-degradation products is probably the modular head-neck junction and may be a function of the geometry of the coupling. Passive dissolution of extensively porous-coated cobalt-alloy stems was not found to be a dominant mode of metal release. CLINICAL RELEVANCE: Increased concentrations of circulating metal-degradation products derived from orthopaedic implants may have deleterious biological effects over the long term that warrant investigation. This is a particularly timely concern because of recent clinical trends, including the reintroduction of metal-on-metal bearing surfaces and the increasing popularity of extensively porous-coated devices with large surface areas of exposed metal. Accurate monitoring of the concentrations of metal in the serum and urine after total hip replacement also can provide insights into the mechanisms of metal release. Our findings suggest that fretting corrosion at the head-neck coupling is an important source of metal release that can lead to increased concentrations of chromium in the serum. Determinations of the concentrations of metal in the serum and urine may be useful in the diagnosis of patients who are symptomatic after a total joint replacement as increased levels are indicative of at least one mode of mechanical dysfunction (for example, fretting corrosion) of the device.

Bypass fixation.

Hip replacement has been a great achievement of orthopaedic surgery as it reliably abolishes pain and restores function. The success of this operation has lead to its use not only in the elderly, but increasingly, in the higher demand that younger patients whose life expectancy is longer than the longevity of the prostheses used to date. Thus, we are seeing a growing number of patients who require a first or even repeat revision surgery, which is often complex and technically demanding.

Extensively coated cementless femoral components in revision hip arthroplasty.

A septic loosening and osteolysis can compromise the available host bone in patients requiring revision hip arthroplasty. Secure fixation of revision femoral components may not be possible if reliant only on proximal femoral bone for biologic fixation or cement interdigitation. The challenge for the revision arthroplasty surgeon is to find the best method to secure the implant in a femur with deficient bone proximally that will provide stability for load bearing and motion. In addition to providing stability, the implant must be durable and maintain long-term fixation. With over 16 years of experience with fully porous coated femoral revision implants, we have found that maximizing prosthetic-bone fit in the proximal femoral diaphyseal bone provides reliable long-term fixation in the majority of femoral revision cases.

Classification of bone defects in failed prostheses.

The authors report a classification system in grades, based on preoperative x-rays of the bone loss surrounding a loosened implant that may be cemented or cementless. Moreover, this classification system allows for the prior choice of which prosthesis to use at the time of reimplantation, and which type of graft depending on whether or not the residual bone guarantees mechanical hold of the implant.

Acetabular reconstruction with massive allograft and cementless prosthesis.

The authors standardize the method to use for a correct approach to acetabular reconstruction in relation to the loss of bone tissue. In type 1 or 2A and C loss, cancellous bone and porous hemispheric acetabula may be used. In type 2B loss there are 3 options: a small acetabulum with a high rotation center, a larger component leaving 30% of the superoexternal portion uncovered, or a larger component with a supporting superoexternal graft. Type 3A requires a supporting graft of distal femur or proximal tibia fused with screws to which a porous hemispheric component with screws is applied. Finally, type 3B loss requires the use of a massive homologous graft fused to the ilium with screws and a component in cemented polyethylene.

Hip revision surgery with cemented, cementless or hybrid prosthesis.

The authors report how the choice of a prosthesis for implantation (cemented or cementless), must be made only after a careful evaluation of the type of osteolysis present. This preoperative evaluation, based on a classification that was previously described, will also guide the choice of any grafts that may be of small size to massive depending on the loss of substance.

Femoral reconstruction with massive allograft and cementless prosthesis.

Classification of loss of bone substance in cases of prosthetic loosening allow for planning of the most suitable type of reconstructive surgery. The use of cemented prostheses has revealed negative long-term results. For this reason a cementless implant which is entirely coated is preferred in order to allow for distal anchoring (particularly in type 2B and 2C loosening). In more severe cases cancellous or cortical bone grafts stabilized by wiring will be used.

Acetabular defect classification: a detailed radiographic approach.

This classification system was developed based on clinically significant recurrent patterns of acetabular bone loss. The classification has now been refined with four specific radiographic parameters that provide specific criteria to classify each defect accurately. This detailed radiographic analysis is based on findings on the plain anterior-posterior pelvis radiograph and eliminates the need for costly computed tomography scans. Each defect classification type also has a clinically proven reconstruction method available. The failed acetabulum can be assessed accurately and easily with this method.

Acetabular distraction: an alternative for severe acetabular bone loss and chronic pelvic discontinuity.

Acetabular bone loss is a challenging problem facing the revision total hip replacement surgeon. Reconstruction of the acetabulum depends on the presence of anterosuperior and posteroinferior pelvic column support for component fixation and stability. The Paprosky classification is most commonly used when determining the location and degree of acetabular bone loss. Augments serve the function of either providing primary construct stability or supplementary fixation. When a pelvic discontinuity is encountered we advocate the use of an acetabular distraction technique with a jumbo cup and modular porous metal acetabular augments for the treatment of severe acetabular bone loss and associated chronic pelvic discontinuity.

Acetabular distraction: an alternative approach to pelvic discontinuity in failed total hip replacement.

A pelvic discontinuity occurs when the superior and inferior parts of the hemi-pelvis are no longer connected, which is difficult to manage when associated with a failed total hip replacement. Chronic pelvic discontinuity is found in 0.9% to 2.1% of hip revision cases with risk factors including severe pelvic bone loss, female gender, prior pelvic radiation and rheumatoid arthritis. Common treatment options include: pelvic plating with allograft, cage reconstruction, custom triflange implants, and porous tantalum implants with modular augments. The optimal technique is dependent upon the degree of the discontinuity, the amount of available bone stock and the likelihood of achieving stable healing between the two segments. A method of treating pelvic discontinuity using porous tantalum components with a distraction technique that achieves both initial stability and subsequent long-term biological fixation is described.

Managing femoral bone loss in revision total hip replacement: fluted tapered modular stems.

If a surgeon is faced with altered lesser trochanter anatomy when revising the femoral component in revision total hip replacement, a peri-prosthetic fracture, or Paprosky type IIIb or type IV femoral bone loss, a modular tapered stem offers the advantages of accurately controlling femoral version and length. The splines of the taper allow rotational control, and improve the fit in femoral canals with diaphyseal bone loss. In general, two centimetres of diaphyseal contact is all that is needed to gain stability with modular tapered stems. By allowing the proximal body trial to rotate on a well-fixed distal segment during trial reduction, appropriate anteversion can be obtained in order to improve intra-operative stability, and decrease the dislocation risk. However, modular stems should not be used for all femoral revisions, as implant fracture and corrosion at modular junctions can still occur.

Massive bone loss: allograft-prosthetic composites and beyond.

Revision total hip arthroplasty (THA) is projected to increase by 137% from the years 2005 to 2030. Reconstruction of the femur with massive bone loss can be a formidable undertaking. The goals of revision surgery are to create a stable construct, preserve bone and soft tissues, augment deficient host bone, improve function, provide a foundation for future surgery, and create a biomechanically restored hip. Options for treatment of the compromised femur include: resection arthroplasty, allograft prosthetic composite (APC), proximal femoral replacement, cementless fixation with a modular tapered fluted stem, and impaction grafting. The purpose of this article is to review the treatment options along with their associated outcomes in the more severe femoral defects (Paprosky types IIIb and IV) in revision THA.

What would you do?: challenges in hip surgery.

A moderator and panel of five experts led an interactive session in discussing five challenging and interesting patient case presentations involving surgery of the hip. The hip pathologies reviewed included failed open reduction internal fixation of subcapital femoral neck fracture, bilateral hip disease, evaluation of pain after metal-on-metal hip arthroplasty, avascular necrosis, aseptic loosening secondary to osteolysis and polyethylene wear, and management of ceramic femoral head fracture.

Do tantalum components provide adequate primary fixation in all acetabular revisions?

INTRODUCTION: A number of studies have reported favorable results of cementless fixation in acetabular revisions. Nevertheless, the implant bearing on more than 50% of the patient's bone and good primary stability are required. The objective of this study was to determine whether the use of tantalum implants could provide stable reconstruction for any type of acetabular revision. PATIENTS AND METHODS: This study investigated 72 hips (71 patients) implanted with tantalum cups, some with augments, and morselized graft material. The mean age was 60 years (range, 34-84 years). There were 30 males and 41 females. The mean weight was 71 kg (range, 52-102 kg), the mean height was 1.68 m (range, 1.52-1.84 m). Twenty-five revisions were bipolar. Six revisions were performed for infected acetabular loosening. The mean follow-up was 4 years (range, 2-6 years). RESULTS: The mean Merle d'Aubigné score at follow-up was 15.8 points (range, 9-18 points). According to the Paprosky classification of acetabular bone defects, there were 13 type 1 (18%), 14 type 2A (19.5%), 14 type 2B (19.4%), 23 type 3A (31.9%), and eight type 3B (11.2%) acetabular defects, four of which had pelvic discontinuity. Postoperatively, the position of the hip's center of rotation in relation to Köhler's teardrop was 22 mm (range, 5-41 mm) vertically (normal, < 25 mm) and 39 mm (range, 13-55 mm) horizontally (normal, < 35 mm). The mean acetabular inclination was 40 degrees (range, 20 degrees -63 degrees ). The radiographic analysis found no radiolucent line after 1 year and up to the last follow-up. None of the patients required revision for acetabular loosening. Three hips were revised for instability. Two retentive liners and a dual-mobility cup were cemented in the cups that were left in place. DISCUSSION AND CONCLUSION: Given their mechanical properties (coefficient of friction, porosity), tantalum implants provide a stable primary cementless fixation without compromising the center of rotation and without necessarily requiring a structural graft. A single implant range can therefore be used for any type and severity of bone loss and for all types of acetabular reconstruction. Longer follow-up is nevertheless necessary to confirm these encouraging results. LEVEL OF EVIDENCE: Level IV, historical series.