Should the cement mantle around the femoral component be thick or thin?

Outcomes of Birmingham Hip Resurfacing Based on Clinical Aspects and Retrieval Analysis of Failed Prosthesis

This research aims to identify the prevalence of failure for Birmingham Hip Prosthesis (BHR) in total hip arthroplasty and to analyze its reasons from biomaterials and biofunctional perspectives. We present our current analysis and tests on a series of different BHR-retrieved prostheses after premature failure. Relevant clinical data, such as X-ray investigations and intraoperative images for clinical case studies, were analyzed to better understand all factors involved in BHR prosthesis failure. A detailed analysis of the failures highlighted uneven cement distribution, overloading in certain areas, and void formation in the material. A closer investigation using microscopical techniques revealed the presence of a crack originating from the gap between the cement mantle and human bone. Additionally, scanning electron microscopy analyses were conducted as part of the investigation to examine bone cement morphology in detail and better understand the interactions at the interfaces between implant, cement, and bone. In conclusion, this research emphasizes the importance of surgical technique planning and the cementation procedure in the success rate of BHR prostheses. It also underscores the need to carefully evaluate patient characteristics and bone quality to minimize the risk of BHR prosthesis failure. The cementation procedure seems to be essential for the long-term functionality of the BHR prosthesis.

Larger stem to bone diameter ratio predicts lower cemented endoprosthesis failure

BACKGROUND AND OBJECTIVES

With continued advances in treatment options, patients with endoprosthetic reconstruction are living longer and consequently relying upon their devices for a longer duration. Major causes of endoprosthesis failure include aseptic loosening and mechanical failure. In the setting of tumor resection, loss of bone stock and use of radiation therapy increase the risk for these complications. As such, considerations of remaining native bone and stem length and diameter may be increasingly important. We asked the following questions: (1) What was the overall rate of endoprosthesis failure at a minimum of 5-year follow-up? (2) Does resection length increase implant failure rates? (3) Does implant size and its ratio to cortical width of bone alter implant failure rates?

METHODS

We retrospectively analyzed patient outcomes at a single institution between the years of 1999-2022 who underwent cemented endoprosthetic reconstruction at the hip or knee and identified 150 patients. Of these 150, 55 had a follow-up of greater than 5 years and were used for analysis. Radiographs of these patients at time of surgery were assessed and measured for resection length, bone diameter, stem diameter, and remaining bone length. Resection percentage, and stem to bone diameter ratios were then calculated and their relationship to endoprosthesis failure were analyzed.

RESULTS

Patients in this cohort had a mean age of 55.8, and mean follow-up of 59.96 months. There were 78 distal femoral replacements (52%), 16 proximal femoral replacements (10.7%), and 56 proximal tibial replacements (37.3%). There were five patients who experienced aseptic loosening and six patients who experienced mechanical failure. Patients with implant failure had a smaller mean stem to bone diameter (36% vs. 44%; p = 0.002). A stem to bone diameter of 40% appeared to be a breaking point between success and failure in this series, with 90% of patients with implant failure having a stem: bone ratio less than 40%. Stem to bone ratio less than 40% increased risk for failure versus stems that were at least 40% the diameter of bone (6/19 [31.6%] vs. 0/36 [0%]; odds ratio 0.68; p < 0.001). Resection length did not appear to have an impact on the rates of aseptic loosening and mechanical failure in this series.

CONCLUSIONS

Data from this series suggests a benefit to using stems with a larger diameter when implanting cemented endoprostheses at the hip or knee. Stems which were less than 40% the diameter of bone were substantially more likely to undergo implant failure.

Cemented or uncemented fixation: Which allows a more acceptable prosthetic femoral version in total hip arthroplasty?

BACKGROUND

Three-dimensional computed-tomography (3D-CT) planning for primary Total Hip Arthroplasty (THA) typically uses the external femoral surface; as a result, it is difficult to predict the prosthetic femoral version (PFV) for uncemented femoral stems that press-fit to the internal surface of the bone. Cemented fixation allows the surgeon to adjust the version independent of the internal femoral anatomy. We aimed to better understand the effect of the fixation type on PFV.

METHODS

This was a case series study including a total of 95 consecutive patients (106 hips), who underwent uncemented (n = 81 hips) and cemented (n = 25 hips) primary THA using the posterior approach. The surgeon aimed for a PFV of 20°. Our primary objective was to compare PFV in both groups; our secondary objective was to evaluate the clinical outcomes.

RESULTS

The mean (± SD) PFV was 13° (± 9°) and 23° (± 8°) for the uncemented and cemented THA groups (P < 0.001), respectively. In the uncemented THA group, 36% of the patients had a PFV of < 10°. In the cemented THA group, this clinically important threshold dropped to 8%. Similarly, the Bland-Altman (BA) plots showed wider 95% limits of agreement for the uncemented group. Satisfactory clinical outcomes were recorded.

CONCLUSION

We found that the PFV was more clinically acceptable, for the posterior surgical approach, in the cemented group when compared to the uncemented group. Both THA groups reported high variability indicating the need to develop surgical tools to guide the PFV closer to the surgical target.

Minimum 10-Year Follow-Up of Total Hip Arthroplasty With a Collarless Triple-Tapered Polished Cemented Stem With Line-to-Line Implantation Using a Direct Anterior Approach

BACKGROUND

The Trilliance stem (B. Braun-Aesculap, Tuttlingen, Germany), a novel collarless triple-tapered polished stem, was introduced in 2009. The aim of this study is to evaluate the long-term clinical and radiological results of the Trilliance stem with line-to-line implantation in primary total hip arthroplasty using a direct anterior approach.

METHODS

A consecutive retrospective series of 130 patients (151 hips) who underwent total hip arthroplasty between February 2009 and August 2011 were evaluated for a minimum of 10 years. Of these, 87.4% had a diagnosis of secondary osteoarthritis based on developmental hip dysplasia. Clinical and radiological results, complications were evaluated and survival analysis was performed.

RESULTS

The mean follow-up was 10.7 years (range, 10.0-12.1). Thirteen hips (13 patients, 6.8%) were lost to follow-up. Adequate cementation (Barrack grade A) was achieved in 136 hips (93.8%) 1 week post-operatively. Nearly all (144 hips, 99.3%) had been inserted within the range of 3°. No significant differences were identified between high- (≥30 procedures/year) and low- (<30 procedures/year) volume surgeons. The Kaplan-Meier survival analysis with revision of the femoral component for aseptic loosening, revision of the femoral component for any reason and revision of either component for any reason as the end points, cumulative survivorship was 100.0%, 97.6% (95% confidence interval (CI) 95.4-100.0) and 96.5% (95% CI 93.8-99.3) at 10 years, respectively.

CONCLUSION

The Trilliance stem with line-to-line implantation using a direct anterior approach has an excellent clinical and radiological outcome at a minimum of 10 years' follow-up.

LEVEL OF EVIDENCE

Level IV, Retrospective cohort study.

Femoral Stem Cementation in Primary Total Hip Arthroplasty

➢

Femoral stem cementation has undergone considerable investigation since bone cement was first used in arthroplasty, leading to the evolution of modern femoral stem cementation techniques.

➢

Although there is a worldwide trend toward the use of cementless components, cemented femoral stems have shown superiority in some studies and have clear indications in specific populations.

➢

There is a large evidence base regarding cement properties, preparation, and application techniques that underlie current beliefs and practice, but considerable controversy still exists.

➢

Although the cementing process adds technical complexity to total hip arthroplasty, growing evidence supports its use in certain cohorts. As such, it is critical that orthopaedic surgeons and investigators have a thorough understanding of the fundamentals and evidence underlying modern cementation techniques.

Revision total elbow arthroplasty using intramedullary strut allograft for aseptic loosening of the humeral stem

Total elbow arthroplasty (TEA) has become a well-accepted treatment option for many pathologies of the elbow joint. Its use in distal humerus fractures in elderly patients has become increasingly popular and has good clinical results. However, with the aging population and the increasing number of TEAs performed, so comes the potential for an increasing number of revision TEA cases. Revision TEA can be extremely challenging. In addition to the technical difficulties of safe exposure and implant removal, reimplantation of a cemented humeral component with loss of bone stock can be a challenging step in this procedure. The purpose of this article was to describe a novel technique to address aseptic loosening of the humeral stem and loss of humeral bone stock with revision of the humeral component using a long-stemmed cemented implant and intramedullary allograft fibular strut bone grafting.

Survivorship of the C-Stem total hip replacement using the "French Paradox" technique

BACKGROUND

This study evaluates the survivorship of the C-Stem total hip replacement, using the "French Paradox" method, at medium-term follow-up.

METHODS

321 cemented total hip replacements in 307 patients were performed, using the canal-filling technique for the femoral stem. Survival analysis was performed for all-cause revision. The secondary outcome was aseptic loosening of the stem.

RESULTS

Revision rate for all reasons was 2%. Overall ten-year survival was 95%. There were no revisions for femoral stem aseptic loosening.

CONCLUSION

This is a unique study demonstrating successful outcomes of total hip replacement using the "French Paradox" technique with a triple-tapered stem.

Is the French Paradox cementing philosophy superior to the standard cementing? A randomized controlled radiostereometric trial and comparative analysis

Aims

Highly polished stems with force-closed design have shown satisfactory clinical results despite being related to relatively high early migration. It has been suggested that the minimal thickness of cement mantles surrounding the femoral stem should be 2 mm to 4 mm to avoid aseptic loosening. The line-to-line cementing technique of the femoral stem, designed to achieve stem press-fit, challenges this opinion. We compared the migration of a highly polished stem with force-closed design by standard and line-to-line cementing to investigate whether differences in early migration of the stems occur in a clinical study.

Methods

In this single-blind, randomized controlled, clinical radiostereometric analysis (RSA) study, the migration pattern of the cemented Corail hip stem was compared between line-to-line and standard cementing in 48 arthroplasties. The primary outcome measure was femoral stem migration in terms of rotation and translation around and along with the X-, Y-, and Z- axes measured using model-based RSA at three, 12, and 24 months. A linear mixed-effects model was used for statistical analysis.

Results

Results from mixed model analyses revealed a lower mean retroversion for line-to-line (0.72° (95% confidence interval (CI) 0.38° to 1.07°; p < 0.001), but no significant differences in subsidence between the techniques (-0.15 mm (95% CI -0.53 to 0.227; p = 0.429) at 24 months. Radiolucent lines measuring < 2 mm wide were found in three and five arthroplasties cemented by the standard and line-to-line method, respectively.

Conclusion

The cemented Corail stem with a force-closed design seems to settle earlier and better with the line-to-line cementing method, although for subsidence the difference was not significant. However, the lower rate of migration into retroversion may reduce the wear and cement deformation, contributing to good long-term fixation and implant survival.

Cite this article: Bone Joint J 2022;104-B(1):19–26.

Hip Hemiarthroplasty: The Misnomer of a Narrow Femoral Canal and the Cost Implications

Objective

Hemiarthroplasty has been identified as the treatment of choice for displaced intracapsular femoral neck fractures. A modular prosthesis is sometimes preferred for its sizing options in narrow femoral canals, despite its higher cost and no advantage in clinical outcomes. Thus, in this study, we investigated the factors affecting surgeons’ choice of prosthesis, hypothesizing that modular hemiarthroplasty is overused for narrow femoral canals compared to monoblock hip hemiarthroplasty.

Methods

A retrospective study of a regional level 1 trauma center was conducted. Patients who had sustained femoral neck fractures from March 2013 to December 2016 were included in this study. Inclusion criterion was modular hemiarthroplasty for a narrow femoral canal. A matched group of patients who underwent monobloc hemiarthroplasty (MH) was created through randomization. The main outcome measurements were sex, age, Dorr classification, and femoral head size. We measured the protrusion of the greater trochanter beyond the level of the lateral femoral cortex postoperatively. Modular hemiarthroplasty patients were templated on radiographs using TraumaCad for Stryker Exeter Trauma Stem (ETS®).

Results

In total, 533 hemiarthroplasty procedures were performed, of which 27 were modular for a narrow femoral canal. The ratio of modular to monobloc was 1:18. Average head size was 46.7 mm ± 3.6 mm for monobloc and 44.07 ± 1.5 for modular (P= 0.001). There were four malaligned stems in the monobloc group versus 14 in the modular group (P= 0.008). Unsatisfactory lateralization was noted in 18 patients (7 mm ± 2.9 mm) in the modular group compared with 8 (4.7 mm ± 3.9 mm) in the monobloc group (P= 0.029). Dorr classification was A or B in 24 patients in the modular group and 18 in the monobloc group (P = 0.006). Templating revealed that modular was not required in 25 patients.

Conclusions

As per our findings, it was determined that patients with a narrow femoral canal intraoperatively should not receive modular hemiarthroplasty. This is especially true for female patients with small femoral head and narrow femoral canal dimensions (Dorr A and B). They would require extensive careful planning. Surgical techniques should be explored through education intraoperatively to achieve lateralization during femoral stem preparation. This may avoid prolonged anesthetic time and achieve potential cost savings.

Does the line-to-line cementing technique of the femoral stem create an adequate cement mantle?

BACKGROUND

The line-to-line cementing technique is proposed to create a press-fit in the femoral canal, which is contrary to modern cementing techniques. The term 'French paradox' has been used to describe the acceptable results associated with this technique. It has been suggested that the quality of the mantle may not be satisfactory, predisposing to early failure and aseptic loosening.

METHODS

The line-to-line cementing technique, where the femoral stem was oversized by 1 size compared to the broach, was compared to the standard cementing technique using corresponding sized broaches and stems, in 6 pairs of human cadaver femora with taper-slip design C-stems. Cement pressure was measured, and cement mantle thickness was analysed. A mixed effects model with random intercepts was used to examine the relationship between thickness of mantle and cementing technique and between pressure and cementing technique.

RESULTS

Line-to-line cementing results in significantly higher pressurisation for longer periods of time leading to better interdigitation but a thinner mantle in some areas.

CONCLUSIONS

The results of this study describe the in-vitro advantages and disadvantages of the line-to-line cementing technique.

Outcomes of Cemented Distal Femoral Replacement Using "Line to Line" Technique With All-Polyethylene Tibial Implant for Tumors

BACKGROUND

Both cemented and cementless stemmed endoprosthetic implants have been used to reconstruct large skeletal defects after tumor resection with similar outcomes. In this study, we examined the oncologic, clinical, and functional outcomes in patients undergoing distal femur replacement using the French paradox technique.

METHODS

A total of 125 patients who underwent distal femur replacement between 1990 and 2019 using the line-to-line cementation technique were reviewed. Implant failure was recorded as per Henderson's classification. Functional outcomes were analyzed using the Musculoskeletal Tumor Society and Toronto Extremity Salvage Score scoring systems. The mean follow-up was 84 (1-350) months.

RESULTS

Aseptic loosening of the femoral stem was recorded in one patient at 21-years of follow-up. Twenty of 125 patients required bushing exchange for polyethylene wear, all after 10 years. Six tibial bearing component fractures were recorded in four patients while one femoral stem component Morse taper fractured. Two all-polyethylene cemented tibial implants were revised for polyethylene granuloma. Deep surgical site infection occurred in 13 patients, while six patients experienced local recurrence. Kaplan-Meier estimates for implant survival for all-cause revision were 85% at 1 year and 70% at 5 years. These estimates for femur or tibia loosening as an end point were 96% at 10 years and 90% at 15 years. The mean Musculoskeletal Tumor Society and Toronto Extremity Salvage Score scores at the last follow-up were 76% and 74%, respectively. Thirty-five patients died of disease progression.

CONCLUSION

The line-to-line cementation technique, used with all-polyethylene tibial implants, demonstrates low incidence of aseptic loosening at medium and long-term follow-ups.

LEVEL OF EVIDENCE

III.

Minimum ten-year outcome of a triple-tapered femoral stem implanted with line-to-line cementing technique

Background

A triple-tapered polished femoral stem was implanted with line-to-line cementing technique. The purpose of this study was to determine the survivorship, loosening rate, stem subsidence, radiologic changes and clinical outcomes in the minimum 10-year follow-up.

Methods

This was a retrospective study done in three institutes. Finally, 118 hips in 97 patients could be followed-up at the mean follow-up period of 126.3 months. The survivorship, radiological and clinical outcomes were investigated.

Results

Radiologically, 107 hips (90.7%) were categorized to Barrack cementing grade A, and 108 stems (91.5%) were inserted in neutral position. All hips were not loose and were not revised due to any reason. Survival with revision for any reason as the endpoint was 100% after 10 years. At the last follow-up, the mean subsidence was 0.43 mm, and the subsidence was less than 1 mm in 110 hips (93.2%).

JOA hip score improved from 42.7 ± 8.9 points preoperatively to 92.8 ± 6.8 points at the last follow-up. No patient complained thigh pain.

Conclusions

Line-to-line cementing technique with use of a triple-tapered polished stem was effective to achieve good cementation quality and centralization of the stem. The subsidence was small, and the minimum 10-year results were excellent without any failures related to the stem.

Trial registration

Retrospectively registered.

The Effect of a Distal Centralizer on Cemented Femoral Stems in Arthroplasty Shown on Radiographs and SPECT/CT: A Case Report

CASE

A 70-year-old female patient underwent total hip arthroplasty (HA) using a stem cemented line-to-line without centralizer. Postoperatively, she complained of load-dependent thigh pain. Conventional radiographs identified cortical overload because of a distal cement mantle discontinuity at the level of the stem's tip, confirmed by single-photon emission computed tomography/computed tomography scan (SPECT/CT). After cement-in-cement revision using a stem with centralizer, pain ceased rapidly. The cortical overload disappeared, as confirmed on a following SPECT/CT performed for low back pain.

CONCLUSION

In HA, the stem's tip may cause overload on the bone's cortex if the cement mantle is incomplete. Implanting a stem with centralizer avoids or cures this.

The Effects of Rasp Oversize on the Clinical and Radiographic Outcomes of Total Hip Arthroplasty With a Collared Satin-Finished Composite Beam Cemented Stem

BACKGROUND

This study aimed to compare the clinical and radiographic outcomes of using two different oversized rasps in total hip arthroplasty (THA) with a composite beam cemented stem (DCM-J).

METHODS

A consecutive series of 105 hips underwent hybrid THA using the DCM-J stem between 2006 and 2010. Among the patients with a minimum 10-year follow-up, a 1.5-mm oversized rasp was used in 38 hips (group S), whereas a 0.5-mm oversized rasp was used in 36 hips (group M). The Japanese Orthopedic Association hip score and radiographic findings were evaluated, including cement mantle thickness, stress shielding, and cortical hypertrophy.

RESULTS

The Japanese Orthopedic Association hip score was significantly improved postoperatively with 100% of the implant survival rate in both groups when septic loosening was excluded. Radiographic assessment performed immediately postoperatively revealed that the cement mantle thickness was significantly larger in group M than group S in Gruen zone 1 but did not differ between groups in zones 2-7. Stress shielding was significantly more frequent in group M than group S at 2 years (P = .011), 5 years (P = .012), and ≥10 years postoperatively (P = .038). Cortical hypertrophy appeared in a time-dependent manner; however, the prevalence did not significantly differ between groups at final follow-up at a mean of 11.7 years (range 10-14 years) postoperatively.

CONCLUSIONS

The DCM-J stem achieved good clinical results in both groups. Stress shielding was significantly more frequent in THA using the 0.5-mm rasp than the 1.5-mm rasp, indicating that sufficient cement mantle room should be prepared for the cemented stem.

Distal femoral replacement - Cemented or cementless? Current concepts and review of the literature

Distal femoral endoprosthetic replacement has been successfully used to reconstruct distal femoral defects after tumor resection for over four decades. Despite continued advances, aseptic loosening continues to be the most common failure mode after infection. Debate still exists about a variety of design features and the optimal fixation method remains controversial. To date, no large-scale study or meta-analysis has demonstrated the superiority of one fixation technique over another. While the classic dichotomy of cemented versus cementless stems is well-known, the contemporary surgeon needs to fully understand the optimal clinical setting for each type of fixation technique and additional strategies to maximize implant stability. In clinical practice, the choice of fixation must be tailored to the individual patient. The surgeon must consider whether the operation is being performed for primary sarcoma or metastatic carcinoma, the presence of distant metastases, age, comorbidities, and whether radiotherapy has been previously given or will be required at the site of fixation. The best strategy for each patient optimizes tumor control and appropriately weighs risks of fixation failure versus the expected patient survival. This review will explore cemented and uncemented distal femoral replacement and highlight modern concepts to optimize each technique.

Radiographic, Functional, and Oncologic Outcomes of Cemented Modular Proximal Femur Replacement Using the "French Paradox" Technique

BACKGROUND

Endoprostheses are frequently used in the management of tumors involving the proximal femur. Aseptic loosening is a common complication that has been linked to the cementing technique. The "French paradox" is well-known cementing technique in the arthroplasty literature. No previous reports have assessed loosening in proximal femur replacements using this technique. We examined rates of femoral stem aseptic loosening in proximal femur replacements, functional outcomes, complications, and oncologic outcomes.

METHODS

We conducted a retrospective review of 47 patients who underwent proximal femur replacement between 2000 and 2019. Two reviewers evaluated preoperative and postoperative radiographs using the International Society of Limb Salvage scoring system and Barrack criteria for stem loosening. The acetabulum was evaluated according to the criteria of Baker et al. Functional outcomes were assessed using Musculoskeletal Tumor Society (MSTS) score and Toronto Extremity Salvage Score. The mean follow-up was 44 months.

RESULTS

The mean International Society of Limb Salvage scores for the 2 reviewers were 86% ± 6% and 84% ± 6%. The first reviewer graded femoral stem loosening as "possibly loose" in 2 patients, one of whom was graded as possibly loose by the second reviewer. The 2 reviewers found no acetabular erosion in 16 (70%) and 15 (65.4%) patients, respectively. The mean Musculoskeletal Tumor Society score and Toronto Extremity Salvage Score at last follow-up were 61% and 72%, respectively. Twenty complications occurred in 13 patients, and 5 patients experienced local recurrence.

CONCLUSION

Despite complications, we showed favorable femoral component survival rates. Cementing the proximal femur prosthesis with tight canal fit and thin cement mantle is a viable option for the short and medium term.

LEVEL OF EVIDENCE

III.

Topographic modeling of early human osteoarthritis in sheep

Articular cartilage damage occurring during early osteoarthritis (OA) is a key event marking the development of the disease. Here, we modeled early human OA by gathering detailed spatiotemporal data from surgically induced knee OA development in sheep. We identified a specific topographical pattern of osteochondral changes instructed by a defined meniscal injury, showing that both cartilage and subchondral bone degeneration are initiated from the region adjacent to the damage. Alterations of the subarticular spongiosa arising locally and progressing globally disturbed the correlations of cartilage with subchondral bone seen at homeostasis and were indicative of disease progression. We validated our quantitative findings against human OA, showing a similar pattern of early OA correlating with regions of meniscal loss and an analogous late critical disturbance within the entire osteochondral unit. This translational model system can be used to elucidate mechanisms of OA development and provides a roadmap for investigating regenerative therapies.

Current concepts and outcomes in cemented femoral stem design and cementation techniques: the argument for a new classification system

Cemented implant fixation design principles have evolved since the 1950s, and various femoral stem designs are currently in use to provide a stable construct between the implant-cement and cement-bone interfaces.Cemented stems have classically been classified into two broad categories: taper slip or force closed, and composite beams or shaped closed designs. While these simplifications are acceptable general categories, there are other important surgical details that need to be taken into consideration such as different broaching techniques, cementing techniques and mantle thickness.With the evolution of cemented implants, the introduction of newer implants which have hybrid properties, and the use of different broaching techniques, the classification of a very heterogenous group of implants into simple binary categories becomes increasingly difficult. A more comprehensive classification system would aid in comparison of results and better understanding of the implants' biomechanics.We review these differing stem designs, their respective cementing techniques and geometries. We then propose a simple four-part classification system and summarize the long-term outcomes and international registry data for each respective type of cemented prosthesis. Cite this article: EFORT Open Rev 2020;5:241-252. DOI: 10.1302/2058-5241.5.190034.

First application of three-dimensional designing total hip arthroplasty with long uncemented stem for fibrous dysplasia patients combined with hip joint osteoarthritis

Background

In order to treat proximal femur fibrous dysplasia (FD) patients combined with hip joint osteoarthritis (OA), the three-dimensional (3D) designing osteotomy and implantation of femoral component was firstly used for deformity correction and total hip arthroplasty (THA). The purpose is to present the detailed design, perioperative management and evaluate short-term clinical outcomes of this novel therapeutic method.

Method

A retrospective study was performed in twelve FD patients combined with hip joint OA who were treated in our hospital between July 2013 and April 2015. Seven patients received 3D designing combined osteotomy and THA, and the other five patients underwent 3D designing THA only.

Results

All patients were followed-up with an average duration of 47 months (range, 35–56 months). There was no infection, dislocation, postoperative wound problems or mechanical failures. For the seven patients receiving 3D designing corrective osteotomy, the mean extremity lengthening was 2.8 (range, 1.5–4) cm. The average duration of bone union was 4.2 months. The average Harris Hip Score was improved from 46.08 (range, 13–67) points preoperatively to 93.72 (range, 83–100) points at the last follow-up. The average modified criteria of Guille was improved from 3.2 (range, 1–7) points preoperatively to 8.6 (range, 6–10) points at the last follow-up.

Conclusions

The 3D designing THA with long uncemented stem, including 3D designing corrective osteotomy and implantation of long prosthesis stem, seems to be a reliable method for FD patients combined with hip joint OA. Through preoperative 3D design, corrective osteotomy and implantation of long prosthesis stem can be precise to re-store alignment, uttermost preserve host bone, obtain primary stem stability and provide necessary condition for long-term stem survival, finally leading to better limb function. Besides, perioperative management should be abided strictly for late stability. Nevertheless, the outcomes of long-term follow-up and larger cases are still required.

Standard and line-to-line cementation of a polished short hip stem: Long-term in vitro implant stability

The current trend is toward shorter hip stems. While there is a general agreement on the need for a cement mantle thicker than 2 mm, some surgeons prefer line-to-line cementation, where the mantle has only the thickness provided by the cement-bone interdigitation. The aim of this study was to assess if a relatively short, polished hip stem designed for a standard cementation can also be cemented line-to-line without increasing the risk of long-term loosening. Composite femurs with specific open-cell foam to allow cement-bone interdigitation were used. A validated in-vitro biomechanical cyclic test replicating long-term physiological loading was applied to femurs where the same stem was implanted with the Standard-mantle (optimal stem size) and Line-to-line (same rasp, one-size larger stem). Implant-bone motions were measured during the test. Inducible micromotions never exceeded 10 μm for both implant types (differences statistically not-significant). Permanent migrations ranged 50-300 μm for both implant types (differences statistically not-significant). While in the standard-mantle specimens there was a pronounced trend toward stabilization, line-to-line had less tendency to stabilize. The cement cracks were observed after the test by means of dye penetrants: The line-to-line specimens included the same cracks of the standard-mantle (but in the line-to-line specimens they were longer), and some additional cracks. The micromotions and cement damage were consistent with those observed in-vitro and clinically for stable stems, confirming that none of the specimens became dramatically loose. However, it seems that for this relatively short polished stem, standard-mantle cementation is preferable, as it results in less micromotion and less cement cracking. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2736-2744, 2018.

First application of 3D design custom-made uncemented prosthetic stem for distal femoral cemented megaprosthesis revision

Objectives

3D design, which is widely used in orthopedics, can be applied for precise distal femoral megaprosthetic revision. This research aimed to present and evaluate the design, perioperative management, and mid-term clinical outcomes of a 3D design custom-made uncemented prosthetic stem.

Methods

Between January 2014 and January 2016, seven patients received 3D design custom-made uncemented prosthetic stem revision at our institution. Clinical records and radiographs were evaluated retrospectively.

Results

There were no hardware-related complications during the follow-up (average 24.3 months; range 24–48 months). The average Musculoskeletal Tumor Society (MSTS) score at the last follow-up after revision (27.7 points, range 25–28 points) was significantly higher than that before (16.0 points, range 13–18 points). In addition, the range of motion (ROM) of the affected knee, and the scores of pain, function, emotional acceptance, support, walking and gait all improved significantly. The antecurvature radian of the revision stem averaged at 3.6°. Of the seven patients, three received femoral stem revision and four received revision of the femoral stem and the femoral component; three of them used longer prostheses than the others. There were no significant differences in function between these two groups at the last follow-up after revision.

Conclusion

The 3D design custom-made prosthesis is a typical precision medicine technology in oncologic orthopedics. Characterized by its individually and precisely designed uncemented stem, it offers an alternative option for distal femoral cemented prosthesis revision. Besides the 3D design itself, the perioperative management, especially the techniques for stem implantation, and long-term follow-up are also crucial.

Biomechanics of a cemented short stem: Standard vs. line-to-line cementation techniques. A biomechanical in-vitro study involving six osteoporotic pairs of human cadaver femurs

BACKGROUND

Short-stem total hip arthroplasty (THA) potentially offers advantages compared to conventional THA, including sparing bone and soft tissue and being a facilitated and less traumatic implantation. However, the indication is limited to patients with sufficient bone quality. Cemented short-stem THA might provide an alternative to conventional cemented THA. To date, no cemented short stem is available on the market.

METHODS

In the present in vitro study, primary stability of a new cemented short stem was evaluated, comparing standard (undersized stem) versus line-to-line (same-sized stem) cementing techniques, using six pairs of human cadaver femurs. Primary stability, including reversible micromotion and irreversible migration, was assessed in a dynamic material-testing machine. Fracture load was tested and fracture pattern analyzed.

FINDINGS

Both cementation techniques (standard vs. line-to-line) displayed comparable results with respect to primary stability without any statistical differences (micromotion: 17.5 μm vs. 9.6 μm (p = 0.063); migration: 9.5 μm vs. 38.2 μm (p = 0.188)). Regarding fracture load, again, no difference was observed (3670 N vs. 3687 N (p = 0.063)). In all cases, proximal fractures of Vancouver type B3 occurred.

INTERPRETATION

The present in vitro study demonstrates that the line-to-line cementation technique, which is favourable regarding the philosophy of short stem THA, can be further pursued in the course of the development of a cemented short stem. Further investigations should address how well the cemented short stem compares to well-established cemented straight-stem designs.

Effect of Human Adipose Tissue Mesenchymal Stem Cells on the Regeneration of Ovine Articular Cartilage

Cell therapy is a promising approach to improve cartilage healing. Adipose tissue is an abundant and readily accessible cell source. Previous studies have demonstrated good cartilage repair results with adipose tissue mesenchymal stem cells in small animal experiments. This study aimed to examine these cells in a large animal model. Thirty knees of adult sheep were randomly allocated to three treatment groups: CELLS (scaffold seeded with human adipose tissue mesenchymal stem cells), SCAFFOLD (scaffold without cells), or EMPTY (untreated lesions). A partial thickness defect was created in the medial femoral condyle. After six months, the knees were examined according to an adaptation of the International Cartilage Repair Society (ICRS 1) score, in addition to a new Partial Thickness Model scale and the ICRS macroscopic score. All of the animals completed the follow-up period. The CELLS group presented with the highest ICRS 1 score (8.3 ± 3.1), followed by the SCAFFOLD group (5.6 ± 2.2) and the EMPTY group (5.2 ± 2.4) (p = 0.033). Other scores were not significantly different. These results suggest that human adipose tissue mesenchymal stem cells promoted satisfactory cartilage repair in the ovine model.

Treatment with embryonic stem-like cells into osteochondral defects in sheep femoral condyles

Background

Articular cartilage has poor intrinsic capacity for regeneration because of its avascularity and very slow cellular turnover. Defects deriving from trauma or joint disease tend to be repaired with fibrocartilage rather than hyaline cartilage. Consequent degenerative processes are related to the width and depth of the defect. Since mesenchymal stem cells (MSCs) deriving from patients affected by osteoarthritis have a lower proliferative and chondrogenic activity, the systemic or local delivery of heterologous cells may enhance regeneration or inhibit the progressive loss of joint tissue. Embryonic stem cells (ESCs) are very promising, since they can self-renew for prolonged periods without differentiation and can differentiate into tissues from all the 3 germ layers. To date only a few experiments have used ESCs for the study of the cartilage regeneration in animal models and most of them used laboratory animals. Sheep, due to their anatomical, physiological and immunological similarity to humans, represent a valid model for translational studies. This experiment aimed to evaluate if the local delivery of male sheep embryonic stem-like (ES-like) cells into osteochondral defects in the femoral condyles of adult sheep can enhance the regeneration of articular cartilage. Twenty-two ewes were divided into 5 groups (1, 2, 6, 12 and 24 months after surgery). Newly formed tissue was evaluated by macroscopic, histological, immunohistochemical (collagen type II) and fluorescent in situ hybridization (FISH) assays.

Results

Regenerated tissue was ultimately evaluated on 17 sheep. Samples engrafted with ES-like cells had significantly better histologic evidence of regeneration with respect to empty defects, used as controls, at all time periods.

Conclusions

Histological assessments demonstrated that the local delivery of ES-like cells into osteochondral defects in sheep femoral condyles enhances the regeneration of the articular hyaline cartilage, without signs of immune rejection or teratoma for 24 months after engraftment.

Electronic supplementary material

The online version of this article (doi:10.1186/s12917-014-0301-9) contains supplementary material, which is available to authorized users.

Which implant should we use for primary total hip replacement? A systematic review and meta-analysis

BACKGROUND

Many total hip implants are currently available on the market worldwide. We aimed to estimate the probability of revision surgery at ten years for each individual total hip implant and to compare these estimates with the National Institute for Health and Care Excellence (NICE) benchmark.

METHODS

We performed a meta-analysis of cohort studies. The methodological quality was assessed with use of the Assessment of Quality in Lower Limb Arthroplasty (AQUILA) checklist. We searched PubMed, Embase, Web of Science, and the Cochrane Library. Additionally, national joint registries that were full members of the International Society of Arthroplasty Registers (ISAR) were hand searched. Studies in which the authors reported the survival probability for either the acetabular or the femoral component of primary total hip replacements with use of revision for any reason or for aseptic loosening at ten years as the end point, with at least 100 implants at baseline, and in which at least 60% of the patients had primary osteoarthritis were eligible for inclusion.

RESULTS

The search strategy revealed 5513 papers describing survival probabilities for thirty-four types of acetabular components and thirty-two types of femoral components. Eight types of acetabular cups and fifteen types of femoral stems performed better than the NICE benchmark.

CONCLUSIONS

We recommend that surgeons performing a primary total hip replacement use an implant that outperforms the NICE benchmarks.

Muscle stretching after immobilization applied at alternate days preserves components of articular cartilage

We compared the response of articular cartilage subjected to muscle stretching at different frequencies after joint immobilization. Wistar rats with immobilized left hind limbs were classified into the following groups: immobilization, immobilization followed by muscle stretching applied daily (group IS7) or three times a week (IS3), muscle stretching applied daily (S7) or three times a week (S3), and a control group (C) that underwent no intervention. We then evaluated the cartilage for cellularity, loss of proteoglycans, collagen density, and immunostaining of fibronectin and chondroitin 4-sulfate. Group IS7 showed a significant increase in cellularity and significant loss of proteoglycan compared with the control. In addition, IS7 group had less proteoglycan than IS3. Thin collagen fibrils were significantly reduced in IS7 rats, compared with IS3 and C. There was a significant decrease in the amount of thick fibrils in all groups compared with the control. Groups IS7 and IS3 showed significantly more intense fibronectin immunostaining than the other groups. Our results show that if applied daily after immobilization, muscle stretching is harmful to articular cartilage. However, when applied on alternate days, muscle stretching preserves the components of articular cartilage. We suggest that the latter frequency is more suitable for treatment.

Radiographic grading of femoral stem cementation in hip arthroplasty

OBJECTIVE:

To determine intra and interobserver agreement of the grading system for femoral cementation in hip arthroplasty proposed by Barrack.

METHODS:

Immediate anteroposterior and lateral postoperative radiographs of 55 primary total hip arthroplasties were assessed by two observers familiar with the use of this grading system. The assessments were performed on two separate occasions by each observer and independently. The statistical analysis measured the Kappa coefficient, which determines the degree of agreement between tests with categorical variables.

RESULTS:

Intraobserver Kappa coefficient varied from 0.43 to 0.68, demonstrating moderate to substantial strength of agreement; interobserver Kappa coefficient varied from 0.19 to 0.44, demonstrating slight to moderate strength of agreement.

CONCLUSION:

Intra and particularly interobserver agreement are limited in this grading system, even when used by trained individuals. Level of Evidence III, Study of nonconsecutive patients; without consistently applied reference "gold" standard.

Surgical treatment of articular cartilage defects in the knee: are we winning?

Articular cartilage (AC) injury is a common disorder. Numerous techniques have been employed to repair or regenerate the cartilage defects with varying degrees of success. Three commonly performed techniques include bone marrow stimulation, cartilage repair, and cartilage regeneration. This paper focuses on current level of evidence paying particular attention to cartilage regeneration techniques.

Combined effect of subchondral drilling and hyaluronic acid with/without diacerein in full-thickness articular cartilage lesion in rabbits

The osteochondral healing potential of hyaluronic acid (HA) plus diacerein was evaluated in subchondral-drilling- (SCD-) induced fibrocartilage generation in rabbits. A full-thickness chondral defect was created along the patellar groove of both knees and then SCD was subsequently performed only in the left knee. A week later, the rabbits were allocated into 3 groups to receive weekly intra-articular (IA) injection for 5 weeks with normal saline solution (NSS) (group 1) or with HA (group 2 and group 3). Starting at the first IA injection, rabbits were also gavaged daily for 9 weeks with NSS (group 1 and group 2) or with diacerein (group 3). The animals were then sacrificed for evaluation. The newly formed tissue in SCD lesions showed significantly better histological grading scale and had higher content of type II collagen in HA-treated group compared to NSS control. In addition, adding oral diacerein to HA injection enhanced healing potential of HA.

A clinical study on glucosamine sulfate versus combination of glucosamine sulfate and NSAIDs in mild to moderate knee osteoarthritis

Background. Glucosamine may be effective in treating and possibly slowing the progression of Osteoarthritis (OA). It is believed Glucosamine supplements may help to stop cartilage breakdown, build cartilage and decrease swelling. Objective. The objective of this study was glucosamine sulfate versus combination of glucosamine sulfate and Non-Steroidal anti-inflammatory drugs (NSAID) in mild to moderate knee osteoarthritis. Methods. Subjects were randomly recruited from Rheumatology outpatient department after a diagnosis of mild or moderate Osteoarthritis. Study tools like patient data collection form, Western Ontario McMaster Universities Arthritis index (WOMAC) of Osteoarthritis questionnaires and Visual Analog Scale (VAS) were used. Results. After 12 weeks, WOMAC total score the result showed that the significant mean difference between the group A and Group B treatment (P < 0.01), with a combination of GS and NSAIDs reducing VAS pain scores. Thus, it is found that Group B treatments over 4 and 12 weeks produced improved WOMAC and VAS grades. Conclusions. Study results may suggest that the Glucosamine Sulfate has a carryover effect like Disease modifying agents. Long-term treatment of Glucosamine Sulfate may reduce the dependence of NSAIDs usage and delay the disease progression. Thereby we can reduce the NSAIDs side effects and improve the patient's quality of life.

Is there still a place for the cemented titanium femoral stem? 10,108 cases from the Norwegian Arthroplasty Register

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.

Hybrid total hip arthroplasty using specifically-designed stems for patients with developmental dysplasia of the hip. A minimum five-year follow-up study

A 4-U hybrid total hip arthroplasty (THA) system was specifically designed for patients with developmental dysplasia of the hip (DDH). Straight stem with an appropriate offset and various size variations are advantages. We followed 128 hips in 124 patients, 13 men and 111 women, for a mean of 6.5 years (range, 5.0-7.5 years). Two acetabular and femoral components in two patients had been revised for infection, one acetabular component had been revised for recurrent dislocation, and one femoral component had been revised for periprosthetic femoral fracture. None of the acetabular or femoral components were revised for loosening or were found to be loose at follow-up. The Harris hip score increased from a preoperative average of 42 points to 88 points at the most recent follow-up. Primary THA using the 4-U system had a good mid-term result in patients with DDH. This system could be applied for all patients including those with the narrowest and deformed femurs.

Is the so-called 'French paradox' a reality?: long-term survival and migration of the Charnley-Kerboull stem cemented line-to-line

We have evaluated the in vivo migration patterns of 164 primary consecutive Charnley-Kerboull total hip replacements which were undertaken in 155 patients. The femoral preparation included removal of diaphyseal cancellous bone to obtain primary rotational stability of the stem before line-to-line cementing. We used the Ein Bild Roentgen Analyse femoral component method to assess the subsidence of the femoral component. At a mean of 17.3 years (15.1 to 18.3) 73 patients were still alive and had not been revised, eight had been revised, 66 had died and eight had been lost to follow-up. The mean subsidence of the entire series was 0.63 mm (0.0 to 1.94). When using a 1.5 mm threshold, only four stems were considered to have subsided. Our study showed that, in most cases, a highly polished double-tapered stem cemented line-to-line does not subside at least up to 18 years after implantation.

Anatomic stem design reduces risk of thin cement mantles in primary hip replacement

PURPOSE

To analyse the influence of femoral stem design in the lateral plane (anatomic vs. straight) on the cement mantle quality.

METHOD

In this consecutive multi-surgeon radiographic study we determined, Dorr grading, cement mantle quality (Barrack) and mantle thickness using Gruen zones 1–14 in 280 primary cemented total hip replacements, divided into two groups (140 anatomic Biomet Olympia, 140 straight Exeter Universal Series).

RESULTS

Twenty-three per cent of the straight Exeter Universal stems had a cement mantle of <2 mm thickness in Gruen zone 8 and 25% in Gruen zone 9, compared to 0.7% of the anatomical Olympia stems in Gruen zone 8 and 1.4% in Gruen zone 9. The difference between the two groups was statistically significant (P < 0.001). In all other zones no significant differences were found.

CONCLUSION

This radiological study confirms that femoral stems with an anatomical curve in the lateral plane carry a lower risk of thin cement mantles (especially in Gruen zones 8 and 9) than straight stems. Cement mantle analysis in one radiographic plane only is insufficient.

18 years of results with cemented primary hip prostheses in the Norwegian Arthroplasty Register: concerns about some newer implants

BACKGROUND AND PURPOSE

Few studies have compared the long-term survival of cemented primary total hip arthroplasties (THAs), and several prostheses have been used without adequate knowledge of their endurance. We studied long-term outcome based on data in the Norwegian Arthroplasty Register.

PATIENTS AND METHODS

The 10 most used prosthesis brands in 62,305 primary Palacos or Simplex cemented THAs reported to the Register from 1987 through 2007 were included. Survival analyses with revision as endpoint (for any cause or for aseptic loosening) were performed using Kaplan-Meier and multiple Cox regression with time-dependent covariates. Revision rate ratios (RRs) were estimated for the follow-up intervals: 0-5, 6-10, and > 10 years.

RESULTS

5 prosthesis brands (cup/stem combinations) (Charnley, Exeter, Titan, Spectron/ITH, Link IP/Lubinus SP; n = 24,728) were investigated with 0-20 year follow-up (inserted 1987-1997). After 18 years, 11% (95% CI: 10.6-12.1) were revised for any cause and 8.4% (7.7-9.1) for aseptic loosening. Beyond 10 years of follow-up, the Charnley cup had a lower revision rate due to aseptic loosening than Exeter (RR = 1.8) and Spectron (RR = 2.4) cups. For stems, beyond 10 years we did not find statistically significant differences comparing Charnley with Titan, ITH, and SP stems, but the Exeter stem had better results (RR = 05). 10 prosthesis brands (9 cups in combination with 6 stems; n = 37,577) were investigated with 0-10 years of follow-up (inserted from 1998 through 2007). The Charnley cup had a lower revision rate due to aseptic loosening than all cups except the IP. Beyond 5 years follow-up, the Reflection All-Poly cup had a 14 times higher revision rate. For stems, beyond 5 years the Spectron-EF (RR = 6.1) and Titan (RR = 5.5) stems had higher revision rates due to aseptic loosening than Charnley. The analyses also showed a marked improvement in Charnley results between the periods 1987-1997 and 1998-2007.

INTERPRETATION

We observed clinically important differences between cemented prosthesis brands and identified inferior results for previously largely undocumented prostheses, including the commonly used prosthesis combination Reflection All-Poly/ Spectron-EF. The results were, however, satisfactory according to international standards.

In vitro cyclic testing of the Exeter stem after cement within cement revision

Cement-within-cement (C-C) revision arthroplasty minimizes the complications associated with removal of secure polymethylmethacrylate. Failure at the interfacial region between new and old cement mantles remains a theoretical concern. This article assesses the cyclic fatigue properties of bilaminar cement mantles after C-C revision in vitro with the Exeter stem. Seven Exeter stems were cemented into Sawbone femurs and removed, and new undersized stems were cemented into the preserved mantle. The new constructs were loaded for 1,000,000 cycles at body temperature. Cement mantles were inspected postcycling. In no case was there delamination or failure of the cement mantle. The findings support the hypothesis that use of a thin revision cement mantle in conjunction with a polished double-tapered stem is not detrimental to the overall success of the implant. In the presence of a secure cement-bone interface in suitable patients, we recommend C-C revision techniques using double-tapered polished femoral stems.

Fixation of the cemented stem: clinical relevance of the porosity and thickness of the cement mantle

The aim of this review paper is to define the fixation of the cemented stem. Polymethyl methacrylate, otherwise known as “bone cement”, has been used in the fixation of hip implants since the early 1960s. Sir John Charnley, the pioneer of modern hip replacement, incorporated the use of cement in the development of low frictional torque hip arthroplasty. In this paper, the concepts of femoral stem design and fixation, clinical results, and advances in understanding of the optimal use of cement are reviewed. The purpose of this paper is to help understanding and discussions on the thickness and the porosity of the cement mantle in total hip arthroplasty. Cement does not act as an adhesive, as sometimes thought, but relies on an interlocking fit to provide mechanical stability at the cement–bone interface, while at the prosthesis– cement interface it achieves stability by optimizing the fit of the implant in the cement mantle, such as in a tapered femoral stem.

The importance of a thick cement mantle depends on stem geometry and stem—cement interfacial bonding

The thickness of the cement mantle around the femoral component of total hip replacements is a contributing factor to aseptic loosening and revision. Nevertheless, various designs of stems and surgical tooling lead to cement mantles of different thicknesses. Opinion is divided on whether a thick mantle enhances implant longevity. This study investigates the effect of cement mantle thickness on accumulated damage in the cement, and how this is influenced by the presence or absence of a proximal collar and on whether the stem—cement interface remains bonded. Three-dimensional finite element simulations incorporating creep and non-linear damage accumulation were performed to investigate cracking in the cement mantles around Stanmore Hips under physiologically informed stair-climbing and gait loads. Cement mantle thickness, stem—cement interfacial bonding, and collar design were varied to assess the interactive effects of these parameters. In all cases, damage levels were three to six times higher when the stem—cement interface remained bonded. Cement mantle thickness had little effect on cement damage accumulation around debonded collared stems but was critical in both bonded and collarless cases, where a thicker mantle reduced cement cracking. Damage around a smooth debonded stem with a collar is thus much less sensitive to cement thickness than around bonded or collarless stems.

Increased long-term failure risk associated with excessively thin cement mantle in cemented hip arthroplasty: a comparative in vitro study

BACKGROUND

There is no consensus on possible detrimental effects of reduced thickness of the cement mantle surrounding hip stems. This work originated from the suspect that a successful design would yield inferior survival when implanted with a lower cement thickness. The scope was to assess with a reproducible in vitro experiment if a thinner cement mantle could cause a reduction of the long-term implant fatigue resistance.

METHODS

A comparative in vitro study was designed based on the same commercial stem (Centrament, Aesculap), implanted with the recommended (2-3mm) and reduced (1-2mm) cement thickness. Tests were carried out simulating 24 years of activity of active hip patients. A multifaceted approach was taken: inducible and permanent micromotions were recorded throughout the test; cement micro-cracks were quantified using dye-penetrants and statistically analyzed; crack surface and stem-cement fretting damage was investigate under Scanning Electron Microscopy.

FINDINGS

The same stem, when implanted with a thinner cement mantle, tended to migrate significantly more (up to 0.3mm), with a tendency to loosen over time (increasing migration rate over time). After cyclic testing the cement mantle of the thinner specimens showed significantly more and longer cracks than the standard implants, with loose cement chips and signs of stem-cement fretting.

INTERPRETATION

All these results confirmed that: (i) the stem under investigation had a good performance (in comparison with similar published work) when implanted with the recommended thickness; (ii) micromotion, cement cracking and fretting damage significantly increased when reduced cement mantle was used. Excessively thin cement mantle can result in critical conditions even for designs, which, in general, show low complications.

Tight fit technique in primary hybrid total hip arthroplasty for patients with hip dysplasia

This article presents the midterm results of hybrid total hip arthroplasty for patients with hip dysplasia by use of a tight fit technique for the femoral component. We followed up 113 hips in 99 patients for a mean of 11 years. All final femoral rasps used in this study overrasped by 0.5 to 1.0 mm for stem insertion, resulting in relatively thin cement mantles. Both components of one hip were removed because of infection. The other 5 acetabular components were revised for osteolysis, recurrent dislocation, or dislodgement of the polyethylene liner. No femoral component was revised for aseptic loosening. We conclude that the tight fit technique using a canal-filling stem may produce good long-term results for patients with hip dysplasia.

The design features of cemented femoral hip implants

We undertook a review of the literature relating to the two basic stem designs in use in cemented hip replacement, namely loaded tapers or force-closed femoral stems, and the composite beam or shape-closed designs. The associated stem fixation theory as understood from in vitro studies and finite element modelling were examined with reference to the survivorship results for each of the concepts of fixation.

It is clear that both design principles are capable of producing successful long-term results, providing that their specific requirements of stem metallurgy, shape and surface finish, preparation of the bone and handling of the cement are observed.

Osteochondritis dissecans of the elbow: Histopathological assessment of the articular cartilage and subchondral bone with emphasis on their damage and repair

Osteochondritis dissecans (OCD) of the elbow is a localized injury of the articular cartilage and subchondral bone that is commonly seen in the young athlete. In the present study, the extent of damage and repair on the articular cartilage and subchondral bone was examined histologically using specimens of 25 osteochondral cylinders and seven loose bodies obtained from 25 young athletes who had undergone osteochondral autograft surgery. Terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end-labeling (TUNEL) assays for detecting apoptotic cells and immunohistochemistry of matrix metalloproteinases (MMP) were performed on the osteochondral cylinder specimens. The histological findings of the OCD of the elbow showed that the articular cartilage exhibited degenerative change, mimicking osteoarthritis, and was markedly damaged as the lesion progressed. TUNEL-positive cells and MMP-3- and -13-expressing cells were distributed in the degenerative articular cartilage and reparative fibrocartilage tissue. Separation occurred at either the deep articular cartilage or the subchondral bone, with the former being dominant in the early OCD lesions. The present results suggest that the primary pathological changes in OCD of the elbow were due to damage of articular cartilage induced by repeated stress following degenerative and reparative process of articular cartilage and subchondral fracturing, and separation subsequently occurred on the cartilage and developed onto the subchondral bone in its advanced stages.

Influence of design variations on early migration of a cemented stem in THA

The clinical results of using different cemented stems in total hip arthroplasty may vary because of shape, surface finish, and choice of metal alloy. Less is known about the influence of size and offset using one and the same design. Data from 140 patients (140 hips) of a cohort constituting 197 patients (231 hips) implanted with cemented Spectron Primary stems were extracted from patients studied in four randomized studies primarily designed for other purposes. Stem size (1, 2, 3, or larger), normal/extra offset, neck length and true offset (horizontal length between the stem and head center of the inserted modular implant) were recorded in millimeters. The radiographic appearance of the cementing was graded on the immediate postoperative radiograph according to Barrack. The patients were examined with radiostereometric analysis of stem migration for a 2-year followup period. Stem Size 1 (the smallest) showed an insignificant increase in subsidence compared with the bigger sizes. Using stepwise linear regression analysis, the quality of the cementing (Barrack C2) was the only parameter that had any certain influence of the subsidence at 2 years. Stem size 2 tended to show minimum valgus alignment and sizes 1 and 3 and bigger showed minimum varus tilting. Our findings suggest that placement of the stem with the tip against the posterior cortex (C2) and stem size influence the primary fixation in different ways. This effect is small, however, indicating that further confirmation with longer followup is necessary.

LEVEL OF EVIDENCE

Therapeutic Level II-1 (prospective cohort study). See the Guidelines for Authors for a complete description of levels of evidence.

High failure rate of a modern, proximally roughened, cemented stem for total hip arthroplasty

The role of surface finish on the survivorship of cemented femoral stems continues to be debated. A total of 34 proximally roughened cemented stems were implanted in 33 consecutive patients undergoing total hip arthroplasty by a single surgeon. An alarmingly high failure rate was observed, prompting a retrospective chart review, analysis of radiographs, and evaluation of retrieved stems and pathological specimens. Nineteen patients were available with more than two years follow-up. Of these 19 patients, nine stems had failed (47%) due to severe osteolysis and stem loosening. Failures were significantly more common in the male gender (p<0.005), and young (p=0.05), tall (p<0.002), and heavy patients (p<0.004). All failed revised hips showed severe metallosis, with both gross and microscopic evidence of metallic shedding from the stems. Our findings suggest that this proximally roughened stem is susceptible to early failure. Failure is characterized by stem debonding, subsidence within the cement mantle, shedding of metallic and cement particles due to fretting, and rapidly progressive osteolysis. These findings have been observed with other rough surface finish cemented stems.

CT analysis of defects of the cement mantle and alignment of the stem

Using a modern cementing technique, we implanted 22 stereolithographic polymeric replicas of the Charnley-Kerboul stem in 11 pairs of human cadaver femora. On one side, the replicas were cemented line-to-line with the largest broach. On the other, one-size undersized replicas were used (radial difference, 0.89 mm sd 0.13).

CT analysis showed that the line-to-line stems without distal centralisers were at least as well aligned and centered as undersized stems with a centraliser, but were surrounded by less cement and presented more areas of thin (< 2 mm) or deficient (< 1 mm) cement. These areas were located predominantly at the corners and in the middle and distal thirds of the stem. Nevertheless, in line-to-line stems, penetration of cement into cancellous bone resulted in a mean thickness of cement of 3.1 mm (sd 0.6) and only 6.2% of deficient and 26.4% of thin cement. In over 90% of these areas, the cement was directly supported by cortical bone or cortical bone with less than 1 mm of cancellous bone interposed.

When Charnley-Kerboul stems are cemented line-to-line, good clinical results are observed because cement-deficient areas are limited and are frequently supported by cortical bone.