Posterior wall acetabular fracture in a 13-year-old boy treated by open reduction and mini-plate internal fixation: long-term follow-up of 17 years.

BACKGROUND: Acetabular fractures are uncommon in children and adolescents, mainly because of predominant cartilaginous component and strong surrounding ligaments. Although acetabular fractures at this age can lead to significant disability, there is no consensus regarding management, which continues to be controversial. Particularly, long-term outcome after operative management has not been evaluated. CASE PRESENTATION: We report a case of a 13-year-old boy skeletally immature who presented with an isolated acetabular fracture involving the posterior wall secondary to a traumatic hip dislocation. A Kocher-Langenbeck approach with a surgical luxation of the hip was used for reduction and mini-plate internal fixation of the fracture. Long-term (17-year) follow-up showed a good clinical outcome and a good congruence of the. The patient has bilateral beginning osteoarthritis due to a cam configuration of both hips CONCLUSION: We describe a case of successful operative management of an acetabulum fracture in a skelettaly immature child with a long-term follow-up. Aggressive management of this rare type of fractures may lead to durable positive outcome.

Prevalence and quantification of contamination of knitted cotton outer gloves during hip and knee arthroplasty surgery.

INTRODUCTION: Knitted cotton outer gloves offer protection against surgical glove perforation and provide improved grip on instruments. These gloves absorb blood and other fluids during surgery, and may therefore also accumulate contaminating bacteria. To date, there is no published data on microbial contamination of such gloves during surgery. METHODS: Knitted cotton outer gloves used in primary and revision hip and knee arthroplasty from two Swiss hospitals were analysed by quantitative bacteriology. Samples were subjected to sonication and vortexing, followed by membrane filtration of the sonicate. Membranes were incubated under aerobic and anaerobic culture conditions, respectively, for 21 days. Total microbial load for each pair of gloves was determined by colony-forming units (CFU) count. Strain identification was performed with MALDI-TOF. RESULTS: A total of 43 pairs of gloves were collected from continuous series of surgeries. Under aerobic culture conditions, total CFU counts ranged 0-1103, 25 (58%) samples remaining sterile, and 4 (9%) yielding > 100 CFU. Under anaerobic culture conditions, total CFU counts ranged 0-3579, 22 (51%) samples remaining sterile, 6 (14%) yielding > 100 CFU. The only covariate significantly associated with the level of contamination was the provider hospital (p < 0.0001 for aerobic and p = 0.007 for anaerobic cultures). Strain identification revealed only skin commensals, mainly coagulase-negative staphylococci and Propionibacterium spp. CONCLUSION: While contamination of surgical latex gloves is a well-known issue, no study has examined so far contamination of knitted cotton outer gloves. No or very low microbial contamination could be identified in the majority of the knitted cotton outer gloves assayed. However, a relevant proportion showed contamination far higher than estimated minimal thresholds for implant-associated infection. Clinical relevance of these findings remains to be established.

Mechanical Testing of Maximal Shift Scarf Osteotomy with Inside-Out Plating Compared to Classic Scarf Osteotomy With Double Screw Fixation.

The purpose of the present study was to biomechanically compare the primary stability of our formerly described inside-out plate fixation to the classic double screw fixation for scarf osteotomy in the treatment of hallux valgus. We performed 20 scarf osteotomies on first metatarsal composite bone models. One half were fixed using a double screw technique and the other half using a locking plate inside-out technique. Using a testing device to simulate the physiologic load, the specimen was loaded until failure, and the load at failure, displacement at failure, and work at failure were recorded. The results were compared between the 2 groups and against the findings from intact sawbones. Compared with the intact bone models, the energy absorption was low for both types of osteotomy fixation. Between the 2 fixation groups, the load at failure was greater for plate fixation, although the difference was not statistically significant (p = .051). However, a statistically significant difference was found between both groups comparing work and displacement at failure (p < .001). In conclusion, the formerly described inside-out plating technique is a biomechanically reasonable alternative to screw fixation because of its primary stability after scarf osteotomy for hallux valgus.

Factors influencing posterior tibial slope and tibial rotation in opening wedge high tibial osteotomy.

PURPOSE: Opening wedge high tibial osteotomy (HTO) is an accepted treatment option for medial compartment knee osteoarthritis with associated varus lower limb axis in younger, more active patients. A concern with the use of this technique is that posterior tibial slope (PTS) and tibial rotation can be altered. We hypothesized that there is a tendency to increase the PTS and internal rotation of the distal tibia during the procedure and that certain intra-operative parameters may influence the amount of change that can be expected. METHODS: A cadaveric model and surgical navigation system were used to evaluate the influence of certain intra-operative factors of the degree of PTS and tibial rotation change observed during medial opening HTO. Parameters evaluated included: degree of osteotomy opening, knee flexion angle, location of limb support (thigh versus foot), performance of a posteromedial release, the status of the lateral cortical hinge, and the degree of osteoarthritis present in the knee. RESULTS: Combining measurements of all specimens and parameters, a mean PTS increase of 2.7° ± 3.9° and a mean tibial internal rotation of 1.5° ± 2.9° were observed. Clinically, significant changes in tibial slope (>2°) occurred in 50.4 % of corrections, while significant changes in tibial rotation (>5°) occurred in only 11.9 % of corrections. Patients with significant osteoarthritis and concomitant flexion contracture, cases where large corrections were required, and procedures in which the lateral cortical hinge was disrupted were associated with increased PTS change. The other factors evaluated did not exert a significant influence of the degree of PTS change observed. CONCLUSIONS: Surgeons should be vigilant for possible PTS change, particularly in high-risk situations as outlined above. Routine use of an intra-operative measure of PTS is recommended to avoid inadvertent slope change.

Optimal culture incubation time in orthopedic device-associated infections: a retrospective analysis of prolonged 14-day incubation.

Accurate diagnosis of orthopedic device-associated infections can be challenging. Culture of tissue biopsy specimens is often considered the gold standard; however, there is currently no consensus on the ideal incubation time for specimens. The aim of our study was to assess the yield of a 14-day incubation protocol for tissue biopsy specimens from revision surgery (joint replacements and internal fixation devices) in a general orthopedic and trauma surgery setting. Medical records were reviewed retrospectively in order to identify cases of infection according to predefined diagnostic criteria. From August 2009 to March 2012, 499 tissue biopsy specimens were sampled from 117 cases. In 70 cases (59.8%), at least one sample showed microbiological growth. Among them, 58 cases (82.9%) were considered infections and 12 cases (17.1%) were classified as contaminations. The median time to positivity in the cases of infection was 1 day (range, 1 to 10 days), compared to 6 days (range, 1 to 11 days) in the cases of contamination (P < 0.001). Fifty-six (96.6%) of the infection cases were diagnosed within 7 days of incubation. In conclusion, the results of our study show that the incubation of tissue biopsy specimens beyond 7 days is not productive in a general orthopedic and trauma surgery setting. Prolonged 14-day incubation might be of interest in particular situations, however, in which the prevalence of slow-growing microorganisms and anaerobes is higher.

Sacroiliac joint syndrome 10 years after lumbar arthroplasty: the importance of spinopelvic alignment.

INTRODUCTION: Sagittal balance is an independent predictor of outcomes in spinal care and several authors focused their attention on the lumbar lordosis restoration as the key point to prevent secondary sacroiliac joint dysfunction (SIJD) after fusion. On the other hand, lumbar disc arthroplasty allows preservation of motion avoiding increased stress on the spinopelvic junction and preventing iatrogenic sagittal imbalance. METHODS: We analyze the incidence of a secondary SIJD and the spinopelvic alignment on a series of 31 consecutive lumbar disc prosthesis with a 10-year follow-up. RESULTS: Sagittal balance assessment showed no significant variation of preoperative spinopelvic parameters. Four patients (12 %) presented a symptomatic SIJD. Only two of them required a percutaneous SIJ fixation. Both of them presented a fused L5-S1 prosthesis. CONCLUSIONS: The low rate of SIJD 10 years after lumbar arthroplasty might be explained by the preservation of the spinopelvic balance.

Metallosis-Induced Warm Antibody Auto-Immune Hemolytic Anemia After Bilateral, Large-Diameter Metal-on-Metal Total Hip Arthroplasty With Complete Remission After Revision.

The use of metal-on-metal bearing couples in total hip arthroplasty can lead to an increased release of metal ions, particularly cobalt and chromium over time. This can lead to local and systemic metallosis, which has cytotoxic, genotoxic, and immunotoxic effects and can cause a host of secondary disorders. We describe the case of a 37-year-old female patient that was diagnosed with warm-antibody autoimmune hemolytic anemia (WAIHA) one and a half years after bilateral large-diameter head metal-on-metal total hip arthroplasty. For 11 years, it was refractory to all therapy, including splenectomy and rituximab, requiring long-term oral prednisone for disease control. Ultimately, systemic metallosis and periprosthetic joint infection were diagnosed, requiring explantation of the prostheses. By the sixth week postoperatively, she experienced complete spontaneous remission of her WAIHA. In conclusion, WAIHA can be associated with systemic metallosis in patients with metal-on-metal prosthetic joint replacements. Both hematologists and orthopedic surgeons should be aware of this.

Associated lesions in posterior wall acetabular fractures: not a valid predictor of failure.

BACKGROUND: The general outcome of posterior wall acetabular fractures is still the source of discussion. Posterior wall fractures are recognized throughout the literature as being difficult to treat. The aim of the present study was to analyze in our own patients the relevance of the classical prognostic criteria for the outcome of isolated posterior wall fractures and those with associated lesions. MATERIALS AND METHODS: A prospective cohort of 33 consecutive patients treated operatively between 1996 and 2006 in a single level 1 trauma center for a posterior wall fracture of the acetabulum was analyzed retrospectively. Included were posterior wall acetabular fractures or associated posterior wall fractures, such as the combinations of posterior column with posterior wall, transverse with posterior wall, or T-shaped fracture with posterior wall fracture. Outcome measurement of the postoperative survival of the hip joints until the primary outcome reoperation (total hip replacement or fusion) and secondary outcome diagnosis of symptomatic osteoarthritis were performed. RESULTS: Twenty-six of the 33 patients with posterior wall fractures also had a dislocated joint. Twelve had isolated and 21 associated fractures. Six patients were reoperated with a THA (four patients within 2 years and one after 10 years), and one arthrodesis was done to treat a hematogenous septic arthritis in a degenerative hip joint. Secondary arthritis was observed in 10 patients. CONCLUSIONS: No difference was found between the outcome in cases of isolated posterior wall acetabular fracture and the outcome in those with associated lesions. The classical prognostic criteria were not found to be relevant to the outcome for our group.

The history of the development of the regular straight stem in hip arthroplasty.

Since the middle of the 20th century, total hip arthroplasty has become a very successful treatment for all end-stage diseases of the hip joint. Charnley solved with his low frictional torque arthroplasty the problem of wear and friction with the introduction of a new bearing couple and the reduction of the head size, which set the prerequisite for the further development of stem design. This narrative review presents the major developments of regular straight stems in hip arthroplasty. It does not only provide an overview of the history but also assembles the generally scarce documentation available regarding the rationale of developments and illustrates often-unsuspected links. Charnley's success is based on successfully solving the issue of fixation of the prosthetic components to the bone, using bone cement made of polymethyl-methacrylate. In the field of cemented anchorage of the stem, two principles showing good long-term revision rates emerged over the years: the force-closed and the shape-closed principles. The non-cemented anchorage bases on prosthesis models ensure enough primary stability for osteointegration of the implant to occur. For bone to grow onto the surface, not only sufficient primary stability is required but also a suitable surface structure together with a biocompatible prosthetic material is also necessary.

Surface repair of the femoral head using press-osteochondral autograft transfer.

Aims: Hyaline cartilage has a low capacity for regeneration. Untreated osteochondral lesions of the femoral head can lead to progressive and symptomatic osteoarthritis of the hip. The purpose of this study is to analyze the clinical and radiological long-term outcome of patients treated with osteochondral autograft transfer. To our knowledge, this study represents a series of osteochondral autograft transfer of the hip with the longest follow-up. Methods: We retrospectively evaluated 11 hips in 11 patients who underwent osteochondral autograft transfer in our institution between 1996 and 2012. The mean age at the time of surgery was 28.6 years (8 to 45). Outcome measurement included standardized scores and conventional radiographs. Kaplan-Meier survival curve was used to determine the failure of the procedures, with conversion to total hip arthroplasty (THA) defined as the endpoint. Results: The mean follow-up of patients treated with osteochondral autograft transfer was 18.5 years (9.3 to 24.7). Six patients developed osteoarthritis and had a THA at a mean of 10.3 years (1.1 to 17.3). The cumulative survivorship of the native hips was 91% (95% confidence interval (CI) 74 to 100) at five years, 62% (95% CI 33 to 92) at ten years, and 37% (95% CI 6 to 70) at 20 years. Conclusion: This is the first study analyzing the long-term results of osteochondral autograft transfer of the femoral head. Although most patients underwent conversion to THA in the long term, over half of them survived more than ten years. Osteochondral autograft transfer could be a time-saving procedure for young patients with devastating hip conditions who have virtually no other surgical options. A larger series or a similar matched cohort would be necessary to confirm these results which, in view of the heterogeneity of our series, seems difficult to achieve.

Treatment of isolated chondral and osteochondral defects in the knee by autologous matrix-induced chondrogenesis (AMIC).

PURPOSE: The purpose of this study is to evaluate clinical and radiological outcomes of patients treated with autologous matrix-induced chondrogenesis (AMIC) for full-thickness chondral and osteochondral defects of the femoral condyles and patella. METHOD: A retrospective evaluation of clinical and radiographic outcomes of patients treated with AMIC for chondral and osteochondral full-thickness cartilage defects of the knee was performed with a mean follow-up of 28.8 ± 1.5 months (range, 13-51 months). RESULTS: Significant improvements in clinical outcome scores (IKDC, Lysholm, Tegner, and VAS pain score) were noted. The largest improvements were seen in the osteochondral subgroup (mean age 25.9 years), whereas patients treated for chondral defects in the patellofemoral joint and on the femoral condyles improved less. Patients in all groups were generally satisfied with their results. MRI evaluation showed that tissue filling was present but generally not complete or homogenous. CONCLUSIONS: AMIC is a safe procedure and leads to clinical improvement of symptomatic full-thickness chondral and osteochondral defects and to regenerative defect filling. The value of AMIC relative to other cartilage repair procedures and to the natural course remains undefined. LEVEL OF EVIDENCE: Case series, Level IV.

A pedicled bone graft from the acromion: an anatomical investigation regarding surgical feasibility.

OBJECTIVE: To investigate the technical feasibility of harvesting a vascularized bone graft from the acromion pedicled on the acromial branch. BACKGROUND: Complex fractures of the proximal humerus may result in partial or total avascular necrosis of the head fragment. Treatment of avascular necrosis of the humeral head is dependent upon the stage of disease as well as the dimension and location of necrosis. In general, the outcome is poor and complete restoration of the shoulder function is rarely attained. Contrary to osteonecrosis of carpal bones (where vascularized bone grafts have been routinely carried out for decades), reports of analogous procedures at the humeral head are anecdotal. METHODS: Based on selective post-mortem computer-tomographic angiography of 5 and the dissection of 30 embalmed human cadaver shoulders, we describe the anatomy of the acromial branch of the thoracoacromial trunk. The main focus was the constancy of its anatomical course, its dimensions and potential use as a nutrient vessel for a pedicled bone graft from the acromion. RESULTS: The course of the acromial branch revealed a constant topographic relationship to anatomical landmarks. Its terminal branches reliably supplied the anterior part of the acromion. The vascularized bone graft could be sufficiently mobilized to allow tension-free transfer to the humeral head as well as to the lateral two-thirds of the clavicle. CONCLUSION: We demonstrated the feasibility of vascularized bone graft harvesting from the acromion. This technique could be a joint-preserving procedure for osteonecrosis of the humeral head or may assist in the revision of a clavicular pseudoarthrosis.

The Incidence of Severe Hypercalcaemia-Induced Mental Status Changes in Patients Treated with Antibiotic-Loaded Calcium Sulphate Depot for Orthopaedic Infections.

Local application of antibiotics with calcium-containing carrier materials (CCCM) might deliver large quantities of calcium, with some cases of hypercalcaemia reported. The incidence of symptomatic hypercalcaemia was estimated retrospectively in a consecutive, prospective series of patients treated between 10/2006 and 02/2019 with antibiotic-loaded CCCM for various orthopaedic infections. Risk factors were analysed. In the study period, 215 CCCM applications were performed. Two patients (0.9%) developed symptomatic hypercalcaemia. In one case, hypercalcaemia occurred 14 days after a second CCCM application during a staged septic hip revision. In the other case, hypercalcaemia became symptomatic six days after application of vancomycin-loaded CCCM in a component-retaining septic revision hip arthroplasty. In both cases, hypercalcemia was not imputable solely to the CCCM. Prolonged immobilization, renal impairment and other specific risk factors were present. Implantation of a CCCM for local application of antibiotics exposes the patient to large quantities of calcium during dissolution. This might induce symptomatic hypercalcaemia, a potentially life-threatening complication. The observed incidence of symptomatic hypercalcaemia remained rare (<1%). In some patients, compensatory mechanisms might be overwhelmed in the presence of other risk factors. Postoperative monitoring of calcaemia as well as elimination of risk factors is mandatory for all patients treated with CCCM.

Wound fluid ceftriaxone concentrations after local application with calcium sulphate as carrier material in the treatment of orthopaedic device-associated hip infections.

AIMS: There is a considerable challenge in treating bone infections and orthopaedic device-associated infection (ODAI), partly due to impaired penetration of systemically administrated antibiotics at the site of infection. This may be circumvented by local drug administration. Knowledge of the release kinetics from any carrier material is essential for proper application. Ceftriaxone shows a particular constant release from calcium sulphate (CaSO4) in vitro, and is particularly effective against streptococci and a large portion of Gram-negative bacteria. We present the clinical release kinetics of ceftriaxone-loaded CaSO4 applied locally to treat ODAI. METHODS: A total of 30 operations with ceftriaxone-loaded CaSO4 had been performed in 28 patients. Ceftriaxone was applied as a single local antibiotic in 21 operations and combined with vancomycin in eight operations, and in an additional operation with vancomycin and amphotericin B. Sampling of wound fluid was performed from drains or aspirations. Ceftriaxone concentrations were measured by liquid chromatography with tandem mass spectrometry (LC-MS/MS). RESULTS: A total of 37 wound fluid concentrations from 16 operations performed in 14 patients were collected. The ceftriaxone concentrations remained approximately within a range of 100 to 200 mg/l up to three weeks. The median concentration was 108.9 mg/l (interquartile range 98.8 to 142.5) within the first ten days. No systemic adverse reactions were observed. CONCLUSION: Our study highlights new clinical data of locally administered ceftriaxone with CaSO4 as carrier material. The near-constant release of ceftriaxone from CaSO4 observed in vitro could be confirmed in vivo. The concentrations remained below known local toxicity thresholds.Cite this article: Bone Joint Res 2022;11(11):835-842.

Does Age Affect the Outcomes of Core Decompression for the Treatment of Kienböck Disease?

Background: Core decompression of the distal radius is a minimally invasive technique that has demonstrated good clinical outcomes in the treatment of Kienböck disease. However, the effectiveness of core decompression has not been compared in different age groups. The aim of this study is to compare the outcomes of core decompression in patients <45 years of age to those ≥45 years of age. Methods: This retrospective study included 36 patients with Kienböck disease who were treated with core decompression over a 20-year period. The mean follow-up was 7 years. Outcome measures included visual analogue scale pain score (VAS), active range of flexion/extension at the wrist, grip strength, and modified Mayo wrist score. The patients were divided into two age groups namely <45 years (younger group; n = 22) and ≥45 years (older group; n = 12) and the outcome measures were compared between the two age groups. Results: There were no statistically significant differences between the outcomes of the two age groups. Conclusion: The outcomes of core decompression of the distal radius for Kienböck disease in older patients (≥45 years) are favorable and similar to those seen in younger patients (<45 years). Level of Evidence: Level III (Therapeutic).

Isolated fractures of the teardrop of the acetabulum.

INTRODUCTION: Fractures of the teardrop are very rare. We would like to present two patients with a fracture of the teardrop. The teardrop is a radiological entity, also known as the U figure. It can be seen on the antero-posterior as well as on the obturator oblique radiographs of the pelvis. It is one of the six fundamental radiographic reference lines corresponding to anatomical landmarks, which Letournel introduced for the evaluation of acetabular fractures. Injuries of the hip joint may include pure hip dislocations, dislocations with fracture of the femoral head, dislocations with fracture of the acetabulum, or both. The position of the femoral head in relation to the acetabulum and the vector of the force at the time of impact determine the type of injury produced. Dislocation of the hip can be classified as posterior, anterior, obturator, or central. Anterior dislocations of the hip are uncommon and constitute 10-15% of traumatic hip dislocations. Anterior dislocations are classified according to the position assumed by the femoral head: pubic, obturator, or perineal. In obturator dislocations, the femoral head can cause a fracture of the infero-medial margin of the acetabulum-the teardrop. METHODS: Two patients are presented with a fracture of the teardrop. Both had a different type of trauma mechanism. The first patient had an obturator hip dislocation combined with a fracture of the teardrop and a fracture of the femoral head. In this case, the intra-articular fragments had to be removed. The second patient had an isolated fracture of the infero-medial margin of the acetabulum probably due to an anterior subluxation and spontaneous relocation of the femoral head. This fracture was treated non-operatively. RESULTS: At 12 and 24 months post-operatively, functional outcome scores were normal, with a normal range of motion and a pain-free hip joint. At 24 months, the radiographs of both patients showed a normal containment of the femoral head inside the joint, no narrowing of the joint space, and no signs of posttraumatic arthritis. CONCLUSIONS AND SIGNIFICANCE: An isolated fracture of the teardrop is very rare. The typical injury mechanism consists in an anterior subluxation or luxation of the femoral head needing hip reduction on an emergency basis. The fracture of the teardrop itself can be treated non-operatively with a perfect functional result, because the infero-medial localization of the fracture does not impair the containment or congruity of the hip joint. In case of a painful or displaced fragment of the teardrop interfering with hip joint mobility, fragment removal may be indicated. In case of an associated supero-lateral femoral head fracture, the fragment can either be internally fixed or debrided depending on its size and fragmentation.

Systemic exposure to tobramycin after local antibiotic treatment with calcium sulphate as carrier material.

INTRODUCTION: Osteoset(®) T is a calcium sulphate void filler containing 4% tobramycin sulphate, used to treat bone and soft tissue infections. Despite systemic exposure to the antibiotic, there are no pharmacokinetic studies in humans published so far. Based on the observations made in our patients, a model predicting tobramycin serum levels and evaluating their toxicity potential is presented. METHODS: Following implantation of Osteoset(®) T, tobramycin serum concentrations were monitored systematically. A pharmacokinetic analysis was performed using a non-linear mixed effects model based on a one compartment model with first-degree absorption. RESULTS: Data from 12 patients treated between October 2006 and March 2008 were analysed. Concentration profiles were consistent with the first-order slow release and single-compartment kinetics, whilst showing important variability. Predicted tobramycin serum concentrations depended clearly on both implanted drug amount and renal function. DISCUSSION AND CONCLUSION: Despite the popularity of aminoglycosides for local antibiotic therapy, pharmacokinetic data for this indication are scarce, and not available for calcium sulphate as carrier material. Systemic exposure to tobramycin after implantation of Osteoset(®) T appears reassuring regarding toxicity potential, except in case of markedly impaired renal function. We recommend in adapting the dosage to the estimated creatinine clearance rather than solely to the patient's weight.

Distal femoral varus osteotomy: problems associated with the lateral open-wedge technique.

INTRODUCTION: Varisation osteotomies on the distal femur are an established treatment method for valgus osteoarthritis of the knee in younger patients. Osteotomy can be done in a lateral open-wedge or medial closed-wedge manner. METHOD: We retrospectively studied 14 patients treated by the lateral open-wedge technique, fixed with the Tomofix plate, with a mean duration of follow-up of 45 ± 3.4 months. RESULTS: We observed often delayed osteotomy healing after 3, 6 and 12 months, no secondary dislocations, and frequent troublesome irritation due to the plate being on the iliotibial band. However, outcome was satisfactory once the osteotomy healed and the plate was removed. CONCLUSION: Based on the often slow healing of the osteotomy and frequent irritation due to the plate, this procedure has been abandoned by the authors, and the medial closing-wedge osteotomy adopted as the alternative treatment.

Removal of an osteointegrated broken uncemented femoral stem after hip arthroplasty-technical note.

Broken stems are particularly challenging in revision hip arthroplasty, as no standard extraction instruments fit anymore. Well-integrated uncemented stem remnants can be particularly arduous to remove. Stem fatigue failure is not rare with modular stems. Since these are particularly useful in revision hip arthroplasty, increasing numbers of broken stems are to be expected. Usually applied techniques using cortical fenestration distally to the tip of the stem or using an extended transfemoral approach cause supplementary bone defects impairing reconstruction. We present a relatively simple and reproducible revision technique, using a limited standard approach and only regular orthopedic instruments, to extract the remnants of broken uncemented femoral stems in hip arthroplasty. This technique was applied successfully and without complications in 6 cases, permitting eventually the reimplantation of even shorter stems.

The different failure modes of the connecting elements of the modular hip arthroplasty revision stem Revitan.

INTRODUCTION: Fracture of the femoral stem is the cause of ~1 % of revisions after total hip arthroplasty. The risk increases intrinsically with modularity, whereby modularity is particularly useful in revision arthroplasty. We present 7 cases of failure of a specific modular, tapered, fluted, titanium alloy Revitan stem and analyse the different failure modes. METHODS: Retrospective review of all Revitan stems revised at our institutions due to implant failure and analysis of clinical presentation, diagnostic workup, and failure mode. The retrieved components were analyzed by optical and scanning electron microscopy. RESULTS: A total of 7 cases were included. There was a significant time lag between symptom onset and correct diagnosis. Conventional radiographs and low-dose CT scans (CT scout imaging) were decisive for diagnosis. All failures occurred at the level of the connection between the proximal component and the distal part of the stem. Three different failure modes were identified: loosening of the proximal component, fatigue fracture of the connection pin, and distal loosening of the connection pin. No alterations of the microstructure or deviation from manufacturing specifications regarding dimensions were observed. Failure was caused by mechanical overload. CONCLUSION: Conventional radiographs are the mainstay in identifying failed modular stems. Repeated radiographs and low-dose CT scans may be helpful additions. No single modification of the connection will address all possible failure modes. Modularity of revision stems offers advantages up until insertion of the definitive stem. Monoblock definitive stems might overcome the potential mechanical weaknesses of modularity and should be considered in relatively young, heavy and active patients.