Cement Fixation Research Articles

Primary Cementless Acetabular Fixation at a Minimum of Twenty Years of Follow-up

The purpose of the present study was to analyze the longer-term results for a previously reported cohort of patients with cementless acetabular fixation and to compare the results with those for historical controls with cement fixation and a comparable follow-up period. One hundred and twenty consecutive nonselected total hip arthroplasties were performed in 108 patients with use of a cementless acetabular component. This series was evaluated at a minimum of twenty years of follow-up and was compared with 330 consecutive hip arthroplasties that had been performed by the same surgeon with use of cemented acetabular components and had been followed for a comparable period of time. Thirty-nine patients (forty-two hips) in the cementless fixation group were living at twenty years of follow-up. In the group of 120 hips with cementless acetabular fixation, twenty-two hips (18.3%) were revised during the follow-up period, but only one hip (0.8%) was revised because of loosening of the acetabular component, with no additional cup loosening since the previous report at thirteen to fifteen years of follow-up. In the group with cemented acetabular fixation with comparable follow-up, thirty-two hips (10%) were revised overall and eighteen hips (6%) were revised because of acetabular loosening. An additional twenty-five hips (8%) had acetabular cups that were loose on radiographs but had not undergone revision. At a minimum of twenty years of follow-up, cementless acetabular components provided superior long-term fixation compared with cemented components but the overall rates of acetabular revision for mechanical reasons were comparable.

Fixation method does not affect restoration of rotation center in hip replacements: A single-site retrospective study

BackgroundAseptic loosening is one of the greatest problems in hip replacement surgery. The rotation center of the hip is believed to influence the longevity of fixation. The aim of this study was to compare the influence of cemented and cementless cup fixation techniques on the position of the center of rotation because cemented cup fixation requires the removal of more bone for solid fixation than the cementless technique.MethodsWe retrospectively compared pre- and post-operative positions of the hip rotation center in 25 and 68 patients who underwent artificial hip replacements in our department in 2007 using cemented or cementless cup fixation, respectively, with digital radiographic image analysis.ResultsThe mean horizontal and vertical distances between the rotation center and the acetabular teardrop were compared in radiographic images taken pre- and post-operatively. The mean horizontal difference was −2.63 mm (range: -11.00 mm to 10.46 mm, standard deviation 4.23 mm) for patients who underwent cementless fixation, and −2.84 mm (range: -10.87 to 5.30 mm, standard deviation 4.59 mm) for patients who underwent cemented fixation. The mean vertical difference was 0.60 mm (range: -20.15 mm to 10.00 mm, standard deviation 3.93 mm) and 0.41 mm (range: -9.26 mm to 6.54 mm, standard deviation 3.58 mm) for the cementless and cemented fixation groups, respectively. The two fixation techniques had no significant difference on the position of the hip rotation center in the 93 patients in this study.ConclusionsThe hip rotation center was similarly restored using either the cemented or cementless fixation techniques in this patient cohort, indicating that the fixation technique itself does not interfere with the position of the center of rotation. To completely answer this question further studies with more patients are needed.

Posterior stabilizer型人工膝関節全置換術における脛骨component周囲の骨透亮像のX線評価

Posterior stabilizer型人工膝関節全置換術における脛骨component周囲の骨透亮像のX線評価

The dog as a preclinical model to evaluate interface morphology and micro-motion in cemented total knee replacement

This study investigated cemented fixation of the tibial component from a canine total knee replacement preclinical model. The objective was to determine the local morphology at the material interfaces (implant, cement, bone) and the local relative micro- motion due to functional loading following in vivo service. Five skeletally mature research dogs underwent unilateral total knee replacement using a cemented implant system with a polyethylene (PE) monobloc tibial component. Use of the implanted limb was assessed by pressure-sensitive walkway analysis. At 60 weeks post-surgery, the animals were euthanatized and the tibia sectioned en bloc in the sagittal plane to create medial and lateral specimens. High resolution imaging was used to quantify the morphology under the tray and along the keel. Specimens were loaded to 50% body weight and micro- motions at the PE-cement and cement-bone interfaces were quantified. There was significantly (p = 0.002) more cement-bone apposition and interdigitation along the central keel compared to the regions under the tray. Cavitary defects were associated with the perimeters of the implant (60 ± 25%). Interdigitation fraction was negatively correlated with cavitary defect fraction, cement crack fraction, and total micro-motion. Achieving good interdigitation of cement into subchondral bone beneath the tibial tray is associated with improved interface morphology and reduced micro-motion; features that could result in a reduced incidence of aseptic loosening. Multiple drill holes distributed over the cut tibial surface and adequate pressurization of the cement into the subchondral bone should improve fixation and reduce interface micromotion and cavitary defects.

Is there still a place for the cemented titanium femoral stem?

Background and purpose Despite the fact that there have been some reports on poor performance, titanium femoral stems intended for cemented fixation are still used at some centers in Europe. In this population-based registry study, we examined the results of the most frequently used cemented titanium stem in Norway.Patients and methods 11,876 cases implanted with the cemented Titan stem were identified for the period 1987–2008. Hybrid arthroplasties were excluded, leaving 10,108 cases for this study. Stem survival and the influence of age, sex, stem offset and size, and femoral head size were evaluated using Cox regression analyses. Questionnaires were sent to the hospitals to determine the surgical technique used.Results Male sex, high stem offset, and small stem size were found to be risk factors for stem revision, (adjusted RR = 2.5 (1.9–3.4), 3.3 (2.3–4.8), and 2.2 (1.4–3.5), respectively). Patients operated in the period 2001–2008 had an adjusted relative risk (RR) of 4.7 (95% CI: 3.0–7.4) for stem revision due to aseptic stem loosening compared to the period 1996–2000. Changes in broaching technique and cementing technique coincided with deterioration of the results in some hospitals.Interpretation The increased use of small stem sizes and high-offset stems could only explain the deterioration of results to a certain degree since the year 2000. The influence of discrete changes in surgical technique over time could not be fully evaluated in this registry study. We suggest that this cemented titanium stem should be abandoned. The results of similar implants should be carefully evaluated.

Surgical treatment and management of hip fracture patients

Osteoporosis-related hip fractures are associated with high mortality and costs. The optimum type of treatment for such fractures is controversial. To shed some light on this issue, the surgical treatment and management of osteoporotic hip fractures were discussed during a hip fracture surgical working group at the 2009 International Society For Fracture Repair Annual Meeting comprising leading experts in the field. The working group consisted of eight orthopaedic surgeons, six industry representatives and one research scientist. Eleven participants were from Europe and four were from the USA and Canada. Two chairmen posed 12 questions relating to the surgical treatment and management of osteoporotic hip fractures. Each question was discussed and key points were noted. Surgery should commence within 24-48 h but the patient should be optimized if presenting with ≥3 comorbidities. Specialized centres integrating orthopaedics, geriatricians and rheumatologists could be a solution for the lack of specialist care post-surgery. Surgical technique is important in fracture fixation, as is the implant, but there has been no improvement in implant design in the past 50 years. As a consequence, malunion has become unjustifiably accepted. Fracture healing can be accelerated using pharmaceuticals which are also important in secondary prophylaxis. All displaced femoral neck fractures in geriatric patients should be treated with hip replacement, the choice between using cemented or uncemented fixation being at the surgeon's discretion. This working group discussion highlighted several important issues which could be of interest to the orthopaedic community.

Total hip arthroplasty: to cement or not to cement the acetabular socket? A critical review of the literature

The optimal method for acetabular socket fixation remains controversial. We present a critical analysis of the current evidence from a systemic literature review of comparative studies, long-term case series, prior literature reviews, meta-analysis, and national arthroplasty registry data for cemented and uncemented acetabular components to determine the respective survivorship rates, overall risk of re-operation, dislocation rates, and wear-related complications. Using contemporary techniques, both cemented and uncemented sockets can yield good long-term results, but our evaluation suggests that the overall/all cause re-operation risk is lower for cemented fixation. Until and unless crosslinked polyethylene (PE) liners or alternative bearings can prove to yield superior outcome in the future, the cemented PE cup remains the gold standard, in all age groups, by which every acetabular component should be compared.

Isolated Polyethylene Liner Exchange in a Revision Total Hip Arthroplasty

Purpose: To analyze the results of isolated exchange of polyethylene (PE) liners for treatment of wear and osteolysis around a well-fixed Harris-Galante (HG) cementless acetabular cup. Materials and Methods: Thirty-three PE liner changes were performed without the removal of stably ingrown implants (33 hips of 32 patients). They were able to be followed for a mean period of 92 months. Clinically, the Harris hip score (HHS), pain evaluation, and complications were evaluated. Radiologically, the annual wear rate and the size of the osteolytic lesions were measured before the operation and the latest follow-up. The bone graft incorporation scale and the development of new osleolytic lesions were checked during the final follow-up. Results: HHS improved to 89.3 at last follow-up. The size of the osteolysis was significantly reduced postoperatively. Bone graft incorporation scales were Grade I in 9 and Grade II in 14 cases. New osteolytic lesions have not developed at latest follow-up. As a complication, one case of dissociation of a liner and a periprosthetic fracture were noted. Annual wear rates during the same period were significantly reduced. There was no sign of alteration in stability of the PE liner. Conclusion: Exchange of a PE liner without removal of stable implants can be a good option for the treatment of wear and osteolysis around a stable cementless THA implant, even if the system has a weak locking mechanism, such as the HG cup. In these cases, under certain states with a higher risk of early failure in the locking mechanism, it would be better to select other revision procedures such as cup revision or cemented polyethylene liner fixation.

EFFECTS OF GEOMETRY OF THE INTRAMEDULLARY STEM OF THE ULNA COMPONENT OF HINGED ELBOW JOINT PROSTHESES ON THE BONE AND IMPLANT BENDING STRESSES

Cemented intramedullary stems are commonly used in total elbow arthroplasty and a considerable amount of time and money are spent for the design of such devices. In the endeavor of reducing production cost of implants, it is of particular interest as to how the geometry of the intramedullary stem can be altered in order to reduce the amount of raw material used in the manufacture of these components. The main aim of this study was to establish a simple mechanics model in preliminary designing of an elbow joint, so that the effects of the geometry of the intramedullary stem of the ulna component of hinged elbow joint prostheses on the bending stress distribution in the ulna bone and the prosthesis stem during static loading after cemented fixation of the implant can be readily estimated. Two mathematical models, namely (i) linear load transfer model and (ii) beams on elastic foundation model were used. The material considered is biocompatible stainless steel (316L). The locations of maximum bending stress occurrence were identified. Special attention was given toward identifying the locations of stress concentrations as well as the degree of stress shielding expected with various stem geometries. The results were compared to that obtained using well-established finite element analysis techniques and the beams on elastic foundation model were chosen to interpret the stresses. It was found that reducing the length of the intramedullary stem or alternatively tapering the distal end of the stem results in a considerable reduction of stress shielding and renders the bending stress distribution in the bone to be more natural. The use of a tapered stem of rectangular cross section showed a 50% reduction in material usage and a reduction of stress shielding compared to that for a stem of uniform circular cross section. Tapered rectangular sections gave the best results in terms of functionality and cost effectiveness. This observation agrees very well with the rationale of implant design that is practiced over the years. The stresses found using this study can be used for preliminary checks against yield and fracture of the stem material and bone material.

Cementless total hip arthroplasty in rheumatoid arthritis: a systematic review of the literature

BackgroundCompromised rheumatic bone is a potential risk factor for mechanical complications in cementless total hip arthroplasty (THA) in cases of rheumatoid arthritis (RA). Increased rates of intra-operative fractures, component migration and (early) aseptic loosening are to be expected. Despite this, cementless THA is performed in cases of RA.MethodsA literature search on cementless THA in RA was performed in EMBASE (1993–2011), Medline (1966–2011) and the Cochrane Library. A systematic review was conducted with a special emphasis on mechanical complications.ResultsTwenty-three case series and five studies of implant registries were included. Acetabular fractures and/or migration of the cup were reported in 9 out of 22 studies of the cup. Proximal femoral fractures and/or subsidence of the stem were reported in 14 out of 20 studies of the stem. Six studies compared failure rates of uncemented and cemented components due to aseptic loosening. The overall failure rate ratio (uncemented/cemented) for the cup was 0.6 (95% CI: 0.14–2.60) and for the stem 0.71 (95% CI: 0.06–8.55), both favoring uncemented fixation. The failure rates in case series without a control group were compared to the NICE criteria (failure rate/1). The overall failure rate for the cup was 0.97 (95% CI: 0.50–1.88) and for the stem 0.79 (95% CI: 0.44–1.41). Failure rates of aseptic loosening of higher than 1 (favoring cemented fixation) were reported in 6 out of 26 studies of the cup and in 2 out of 25 studies of the stem. In all these studies, the inferior implant designs were blamed, and not the type of fixation or the quality of the bone.ConclusionsDespite substantial rates of mechanical stem complications, no evidence was found to establish that cementless components perform less well than cemented components. The results justify the use of cementless THA in RA patients.

Damage evolution in acetabular reconstructs under physiological testing in a saline environment

Damage development in cemented acetabular reconstructs has been studied under a combined cyclic loading block representative of routine activities in a saline environment. A custom-made environmental chamber was designed and installed on the Portsmouth hip simulator to allow testing of acetabular reconstructs in a wet condition for the first time. Damage was monitored and detected by scanning at selected loading intervals using micro-focus computed tomography (μCT). The preliminary results show that, although, as in dry cases, debonding at the bone–cement interface defined the failure of the cement fixation, the combination of mechanical loading and saline environment significantly affected the damage initiation and development, with drastically reduced survival lives of the reconstructs. Debonding was found to be initiated at the bone–cement interface near the rim of the acetabular cup, or DeLee zone I, in wet condition, as opposed to initiation in DeLee zone II near the dome region in dry cases. The survival time of the reconstruct in wet condition is less than 10% of that in dry condition under a given applied hip contact force.

Extended sagittal saw cut significantly reduces fracture load in cementless unicompartmental knee arthroplasty compared to cemented tibia plateaus: an experimental cadaver study

Periprosthetic tibial plateau fractures represent a rare but serious complication in unicompartmental knee arthroplasty and are associated with extended sagittal tibial bone cuts. These can occur during the surgery, weaken the posterior cortex of the tibia and are associated with periprosthetic tibial plateau fractures. Although excellent long-term results have been reported with cemented unicompartmental knee arthroplasty, there is high interest in cementless fixation. The aim of the study was to compare fracture loads of cementless and cemented unicompartmental knee arthroplasty. Tibial components of the Oxford Uni were implanted in six paired fresh-frozen tibiae with a defined extended saw cut (10°) at the dorsal cortex of each specimen. In one set, surgery was performed with cement fixation, and in the other, cementless components were implanted. Vertical loads were then applied under standardised conditions to fracture the specimens. Median loads of 3.7 (0.7-6.9) kN led to fractures in the cemented group, whereas cementless fixated tibiae fractured with a median load of 1.6 (0.2-4.3) kN (P = 0.02). The loading capacity in tibiae with cementless components is significantly less compared to cemented fixation. The results show that in case of an extended sagittal bone cut patients especially those with poor bone quality who are treated with a cementless unicompartmental knee arthroplasty are at higher risk for periprosthetic tibial fractures.

Bilateral Patellar Component Shear Failure of Highly Cross-Linked Polyethylene Components: Report of a Case and Laboratory Analysis of Failure Mechanisms

A case of bilateral patellar component failure due to fatigue fracture of the all-polyethylene fixation pegs in a highly cross-linked ultra–high-molecular-weight polyethylene design is presented. To recreate this failure mode, a novel test method was developed to investigate the effects of peg orientation and cement technique on patella fatigue strength under cyclic compression and shear loading. Patellar peg orientation had a minor effect on shear strength, whereas lack of cement in the backside patellar groove had a substantial effect. The shear fatigue strength exceeded in vivo force estimates when the patellar groove was fully cemented. The test results and retrieval analysis suggest that high activity level and inadequate cement fixation of the patellar component may contribute to all-polyethylene patellar component peg fractures.

29 to 24 Year-Clinical Results of Total Hip Arthroplasty Cemented with HA by Interface Bioactive Bone Cement (IBBC)

To improve the fixation of bone and bone cement in THA we used Interface Bioactive Bone Cement technique (IBBC) since 1982. For prostheses 28 mm-alumina head with polyethylene socket (Kyocera Co.) were used. In IBBC not-resorbable pure crystalline HA granules (0.3– 0.5 mm) were smeared on the bone surface in one to three layers just before packing bone cement. Group 1: IBBC was used in six joints in 1982. Group 2: In 25 patients, conventional bone cement technique (non-IBBC) in the one hip (in 1985 to 1986) and IBBC technique in the other hip (in 1986) were performed in the same patients. Group 3: In 65 patients (71 joints) IBBC were performed. Neither radiolucent line nor osteolysis appeared in all case in group 1. In group 2 in Non-IBBC the appearance rate of radiolucent line and osteolysis were rather high, however in IBBC they were extremely low. In Non-IBBC loosening were seen in 5 joints in the acetabulum and in 2 joints in the femur. However, in IBBC there was no loosening. In group 3 the radiolucent line and the osteolysis appeared extremely low. There was no loosening. In Non-IBBC the appearance rate of radiolucent line and the osteolysis was very high and the rate of loosening was 20%. However, in IBBC, radiolucent line and osteolysis will be prevented eternally.

Cement Fixation in Primary Total Knee Arthroplasty

Cement Fixation in Primary Total Knee Arthroplasty

The effect of cup inclination and wear on the contact mechanics and cement fixation for ultra high molecular weight polyethylene total hip replacements

The present study aimed to investigate individual and combined influences of the cup inclination and wear on the contact mechanics and fixation of a Charnley hip replacement using finite element method. The effects of cup inclination and penetration on the contact mechanics of articulating bearings as well as the stress within the cement and at the bone–cement interface were examined. The maximum contact pressure and the von Mises stress on the cup were reduced by ∼30% and ∼20% respectively when even a small penetration occurred. However, no large differences were found between different cup penetration depths with regards to either the contact pressure or the von Mises stress. The von Mises stress at the bone–cement interface was predicted almost unaltered with an increased cup inclination angle to 55° for a cup penetration to 4mm. These predictions suggest that the contact mechanics and the cement stress are insensitive to the cup inclination and wear under these normal conditions investigated, therefore explaining the robustness of the Charnley hip implant. An increase in the cup inclination angle to 65°, coupled with a maximum penetration of 4mm, resulted in a large increase in the maximum von Mises stress at the bone–cement interface.

Atypical acetabular bone loss in chronic septic total hip arthroplasty loosening

Background: When a periprosthetic infection is diagnosed, the surgical treatment is usually performed as soon as possible to avoid further bone damage or life threatening complications. There is no report on the radiographic change in patients with untreated infected total hip arthroplasty (THA) for several years. Objective: Report radiographic change in patients with untreated infected THA. Method: Two patients presented with chronic septic loosening of cemented acetabular fixation after total hip replacement at King Chulalongkorn Memorial Hospital. Both patients had mild hip pain and had been lost for follow-up until the bone destruction became very severe. Serial radiographs after the surgeries were evaluated. The Paprosky’s acetabular bone loss classification was used to classify the radiographic findings. Results: Based on the Paprosky’s classification for acetabular bone loss, there were two similar atypical radiographic findings found in both patients. These included pelvic discontinuity from extensive medial acetabular bone loss beyond the Kohler’s line, and minimal superior and inferior acetabular bone loss. Conclusion: These atypical radiographic findings were rarely observed in septic acetabular loosening patients, as infection usually causes patients to present earlier. Following the septic acetabular loosening of THA, surgical procedure should be performed before massive bone damage was demonstrated. Keywords: Acetabular loosening, atypical, cemented fixation, radiographic finding, septic, total hip replacement

Comments on Jacquot et al. “Balloon reduction and cement fixation in intra-articular calcaneal fractures: a percutaneous approach to intra-articular calcaneal fractures”

Dear Editor: We read with great interest the paper by Jacquot et al. [1]. The authors concluded that a percutaneous approach and local balloon reduction followed by polymethyl-methacrylate (PMMA) fixation may be promising and may be used in cases with closed fractures as a primary reduction and fixation tool. This study described a new and minimally invasive method for treating closed intra-articular calcaneal fractures. The limited series achieved good outcomes with minimal complications. However, there are some concerns regarding this study. First, which fracture types would be suitable for local balloon reduction and PMMA fixation? The authors used this technique to reduce joint fragments and achieved good reduction, but we do not think this technique is suitable to all joint-depression fractures. In some calcaneal fractures with malalignment, varus or valgus angulation, local balloon reduction alone might make it difficult to restore calcaneal alignment, and perhaps other reduction methods, such as percutaneous Schanz pin indirect reduction and temporary fixation should be applied. Gupta et al. also used local balloon for calcaneal fractures reduction but only for minimal (<5°) varus calcaneal fractures [2]. For comminuted fractures (Sanders type III and type IV), the posterior articular fractured into more than two fragments, and it was difficult to reduce all fragments into contact with their subtalar counterparts using a balloon only, especially the central fragment. Case 2 of Jacquot’s patients was a Sanders IIIBC fracture; the central fragment was not reduced anatomically and a step was present [1]. Perhaps the short-term outcome was not influenced but it does suggest a limitation of this technique. As is known, the balloon technique was used for vertebral compression fractures just to restore the height of the vertebral body, not to reduce articular fragments. The author has given us a good choice for treating intra-articular calcaneal fractures, but the patients should be selected. For comminuted and severely malaligned calcaneal fractures, open reduction may still be required, as inadequate joint reduction and redislocation of the fragments in highly unstable fractures may occur in a considerable percentage of cases with indirect reduction techniques [3]. Second, the authors reported in the paper that inflation was stopped when reduction did not improve, regardless of how much more pressure was applied. We are interested to know whether failure occurred when using this technique, and which type of fracture was difficult to reduce. Following reduction failure, what technique can be attempted next? Best Regards Hongmou Zhao

Comment to the paper “Balloon reduction and cement fixation in intra-articular calcaneal fractures: a percutaneous approach to intra-articular calcaneal fractures” by Jacquot et al.

Dear Sir We read with interest the comments and questions by Zhao et al. on our paper titled “Balloon reduction and cement fixation in intra-articular calcaneal fractures: a percutaneous approach to intra-articular calcaneal fractures” [1] and we wish to bring some clarification to the matter. First, it is our understanding that open reduction and internal fixation (ORIF) through a lateral approach, the procedure now considered standard treatment, is a difficult technique and plagued with many problems, not the least of which is soft-tissue involvement. Obviously, the more violent the trauma to the bone and soft tissue, the more articular fracture comminution interferes with the achievement of a satisfactory clinical result using the standard technique. Thus, we believe the technique we used in our series avoids the difficulties of standard ORIF. We agree that not only is articular reduction important in joint-depression calcaneal fractures, but restoration of the height and shape of the os calcis is mandatory, as pointed out by other authors [2]. This is why we used not only the balloon technique but other restorative measures, such as lateral compression and temporary plantar cortical wire fixation, to help reduce the bone percutaneously. Restoring the general shape of the bone may be much more important than joint reduction alone. In case 2 in our series [1], a small central fragment was left unreduced. This was corrected percutaneously without trauma to the soft tissue. Knowing whether a better reduction would have been achieved through an extensive approach remains conjectural but is not warranted. Accurate joint reduction is difficult to achieve with the balloon technique; it is also difficult to achieve and maintain with regular ORIF. In short, comminuted joint fractures may not be a contraindication to the balloon technique, but to the contrary may be an indication. In the paper by Gupta et al. [3], severe limitations in the amount of displacement were imposed on the use of the authors’ technique: only minimally displaced (<5°) varus calcaneal fractures were treated. The authors used a percutaneous balloon technique and filled the void using a phosphocalcic compound, which appears to offer no fracture stabilisation properties. We described a percutaneous balloon reduction technique, and do not see the point in using such technique in undisplaced calcaneal fractures and bone filling with a weak compound such as phosphocalcic cement. In our experience, such fractures may be better treated nonoperatively, as is the current recommendation, with good clinical results. Percutaneous techniques already allow varus fracture reduction through lateral compression and percutaneous temporary pin fixation. Other techniques may be necessary or may need to be fine tuned [4]. We favour the use of temporary reduction techniques and fixation using polymethylmethacrylate (PMMA) only to avoid later need for hardware removal and the risks involved with infection and skin breakage in a swollen foot. A matter that was not discussed in our paper was operative timing: reduction may be much easier or more effective when performed as an emergency procedure, a procedure that may be possible using percutaneous techniques in a highly swollen heel fracture. The trend for late operation (as much as three weeks posttrauma) to minimise the risk of skin breakage may render accurate reduction much more difficult, even with ORIF, and necessitate a more extensive, vascularisation-stripping, lateral approach. In all, our view is that we are in the process of enlarging our concepts regarding calcaneal fracture treatment by using a collection of new tools that may improve the final clinical results we offer to our patients and diminish the risk of iatrogenic skin breakage in these difficult fractures. Best regards

Custom total hip arthroplasty in skeletal dysplasia

Osteochondrodysplasias are characterised by aberrant cartilage and bone development; consequently, patients may be subject to premature hip degeneration. In this population hip arthroplasty outcomes are variable. This series reviews the use of custom femoral implants in total hip replacements for patients with severe skeletal dysplasia. We reviewed 14 hips in nine patients with genetic dwarfism. Computed tomography (CT) scans of the pelvis and femurs were used to create custom titanium stems. Postoperative radiographs were reviewed for migration, osteolysis, fracture and restoration of leg length. Pre- and postoperative Harris hip scores (HHS) were compared, with a mean follow-up of 36.3 months. Mean age was 36.5 years (range 15-50 years) and mean height was 48 inches (range 42-55 inches). Three joints were classified as Crowe type I, two type II, three type III and six type IV. Three hips (21%) required revision: two for stem migration and one for acetabular osteolysis. Eleven hips (79%) were stable with signs of osseointegration. No fractures, nerve damage or dislocations occurred. Two stems required cement fixation, and no liners were constrained. Significant osteolysis was seen on three radiographs. All patients walked independently, and mean HHS improved from 45 (24-58) to 71 (47-89). All leg length discrepancies were restored to within 3 mm of equal. This study reports good midterm outcomes in a variety of skeletal dysplasias, thus confirming the efficacy of custom femoral implants in the management of this patient group.