Influence of technique with distally fixed modular stems in revision total hip arthroplasty

SF-36 physical function and general health domains are independent predictors of acute hospital length of stay after hip fracture surgery

OBJECTIVE

The demographics and co-morbidities of individuals may impact healthcare consumption, but it is less understood how premorbid physical and mental function may influence these effects. The aim of this study is to determine patient's pre-fracture quality of life and mobility affect acute hospital burden in the management of hip fracture, using length of stay (LOS) as a proxy for healthcare resource.

MATERIALS AND METHODS

This is a retrospective study which investigated hip fracture patients who underwent surgery over the period of 2017-2020. Variables collected include LOS, age, gender, race, marital status, payer type, ASA score, time to surgery (TTS), type of surgery, fracture type, POD1 mobilization, discharge disposition, pre-fracture SF-36, EQ-5D and Parker mobility score (PMS) based on patient's recollection on admission. These variables were correlated with LOS using binary logistic regression on SAS.

RESULTS

There were 1045 patients, and mean age was 79.5 + 8.57 (range 60-105) years with an average LOS 13.64 + 10.0 days (range 2-114). On univariate analysis, PMS, EQ-5D and all domains of SF-36 except bodily pain (BP), emotional role and mental health were associated significantly with LOS. Amongst the QOL and PMS scores, only the domains of SF-36 Physical Function (PF) (OR = 0.993, p = 0.0068) and General Health perception (GH) (OR 0.992, p = 0.0230) remained significant on the multivariate model.

CONCLUSION

Our study showed that poor premorbid scores of SF36 PF and GH are independent factors associated with longer LOS in hip fracture patients after surgery, regardless of fracture type, age and ASA status. Hence, premorbid SF36 PF and GH can be used to identify patients that are at risk of prolonged hospital stay and employ targeted strategies to facilitate rehabilitation and discharge planning.

Subsidence of monoblock and modular titanium fluted tapered stems in revision hip arthroplasty: A retrospective multicentre comparison study

Background

Tapered, fluted, titanium (TFT) stems have shown good clinical outcomes in revision total hip arthroplasty (rTHA), however concerns exist regarding early subsidence. This study compares subsidence between a modern monoblock 3-degree and a modular 2-degree TFT stem in rTHA.

Methods

A retrospective, international multicentre comparative study was conducted including 64 rTHA in 63 patients. A monoblock TFT stem was used in 37 cases and a modular TFT stem was used in 27 cases. Patient demographics, Paprosky femoral bone loss classification, bicortical contact and stem subsidence were recorded at minimum four week follow up.

Results

There was no statistically significant difference in overall subsidence (p = 0.318) or the rate of subsidence >10 mm between stems. Mean subsidence was 2.13 mm in the monoblock group and 3.15 mm in the modular group. Two stems subsided >10 mm: one in each group. There was no difference in bicortical contact between groups (p = 0.98). No re-revisions were performed.

Conclusions

We found no difference in subsidence between the two stems. Surgeons may consider the use of monoblock stems in rTHA as they have comparably low rates of subsidence and eliminate the small but potentially catastrophic risk of implant fracture at modular junctions associated with modular stems.

EBRA Migration Analysis of a Modular, Distally Fixed Stem in Hip Revision Arthroplasty: A Clinical and Radiological Study

Background: Massive osteolysis of the proximal femur makes stem revision a challenging procedure. EBRA-FCA provides the opportunity to determine stem migration, which is considered a predictive factor for implant survival. In this study, we aimed to analyze the migration behavior of a modular, distally fixed reconstruction prosthesis. Methods: Applying a retrospective study design, we reviewed all consecutive patients who received a cementless MP reconstruction prosthesis (Waldemar Link GmbH & Co. KG, Hamburg, Germany) at our Department between 2005 and 2019. We reviewed medical histories and performed radiological measurements using EBRA-FCA software. Results: A total of 67 stems in 62 patients (female 26; male 36) fulfilled our inclusion criteria. Mean age at surgery was 68.0 (range 38.7−88.44) years. EBRA migration analysis showed a median subsidence of 1.6 mm (range 0.0−20.6) at 24 months. The angle between stem and femur axis was 0.3° (range 0.0°−2.9°) at final follow-up. No correlation between body mass index and increased subsidence was found (p > 0.05). Overall revision-free rate amounted to 92.5% and revision-free rate for aseptic loosening to 98.5%. Furthermore, no case of material breakage was detected. Conclusions: In summary, the MP reconstruction prosthesis showed low subsidence and reduction in the migration rate over the investigated follow-up. Based on this, the modular stem can be considered as a good therapy option in challenging stem revisions offering various options to address the individual anatomical situation.

The Length of Diaphyseal Contact of Tapered Fluted Stems is Highly Dependent on Canal Morphology

BACKGROUND

Diaphyseal fixation remains the mainstay of revision THA. The stability of diaphyseal fixation can be quantified by the extent of contact between the stem and the endosteal cortex. This is highly affected by the morphology of the proximal femur. The purpose of this study was to examine factors affecting diaphyseal contact in the revision THA and to identify preoperative predictors of adequate fixation.

METHODS

Three-dimensional femur models were created from CT scans of 33 Dorr B and C femora. The proximal 120 mm of the femur was omitted to mimic proximal bone deficiency. A tapered fluted stem (3 degrees, 150 mm) model was virtually implanted after reaming of the medullary canal. The contact length between stem and endosteal cortex was measured, in addition to other variables. The relationship between variables was evaluated using Spearman's correlation, and logistic regression analysis was used to identify predictors of the contact length (P < .05).

RESULTS

The contact length varied widely between specimens (66.5 ± 16.6 mm, range: 21-98 mm). Contact increased with the depth of the isthmus below the lesser trochanter (range: 55-155 mm; r² = 0.473, P = .005) and the distance between the isthmus and the distal edge of the damage zone (range: -9 to 96 mm; r² = 0.508, P = .002). Stepwise regression identified the reaming length, distance between fracture and the isthmus, and isthmus diameter as independent predictors of contact length (r = 0.643).

CONCLUSIONS

Contact is limited in specimens where the isthmus is more proximally located. In these cases, supplementary fixation using plating and/or longer, curved prosthesis may be considered.

Clinical, functional and radiographic outcomes after revision total hip arthroplasty with tapered fluted modular or non-modular stems: a systematic review

PURPOSE

The aim of the study was to systematically evaluate clinical outcomes of tapered fluted stems, either monoblock or modular, in revision total hip arthroplasty.

METHODS

PubMed, EMBASE and Web of Science and Cochrane databases were systematically searched by 2 researchers. Clinical studies reporting primarily on survival and re-revision rates, and secondarily on subsidence, dislocation, intraoperative fractures, periprosthetic fractures and infection were included. 2 investigators assessed the quality of the studies.

RESULTS

46 studies were included in this review, reporting on 4601 stem revisions. The pooled re-revision rate was 5.1% and long-term survival ranged from 75% to 98.5%. No differences were observed between monoblock and modular stems regarding re-revision rate, dislocation rate, periprosthetic fracture rate or infection rates. Monoblock stems exhibited more subsidence and modular stems displayed more intraoperative fractures.

CONCLUSIONS

Satisfactory results can be obtained with the use of tapered fluted end-bearing stems. Monoblock stems offer the same clinical results as modular stems.

New Sub-Classification of Vancouver B2 Periprosthetic Hip Fractures According to Fracture Pattern

INTRODUCTION

There is currently a debate on whether all Vancouver type B2 (V-B2) periprosthetic hip fractures (PPHF) should be revised. Vancouver classification takes into account fracture location, implant stability and bone stock, but it does not distinguish between fracture patterns. The aim of our work was to study the different fracture patterns of V-B2 PPHF and to analyze if there is any pattern that presents lower osteosynthesis failure rates.

MATERIAL AND METHODS

All patients with V-B2 PPHF treated by osteosynthesis between January 2009 and January 2019 were included in the study. Using the Gruen system the proximal femur was divided into 3 zones. The lateral zone (Gruen 1±2±3), medial zone (Gruen 5±6±7), and distal zone (Gruen 4±3±5) were analysed and it was determined whether each of the 3 zones was fractured.

RESULTS

56 patients were included in the study. Their mean age was 79 years (R 45 - 92). The chosen treatment was: 39 Open reduction and internal fixation (ORIF), 10 Stem revision and 7 nonoperatively treatment. In ORIF group, no implant complications (0/24) were found in patients with a single fractured zone, while 5 implant complications (5/15) were discovered in patients with two or more fractured areas; this difference was significant (p=0.0147). All patients treated by stem revision had a fracture that involved two or more zones. In the nonoperatively group, the fracture pattern did not influence the treatment because of all of them had a very precarious functional and medical situation.

CONCLUSIONS

V-B2 PPHF treated via ORIF affecting only one zone (medial, lateral, or distal) have a lower risk of complication than those affecting two or more zones. We propose a sub-classification of Vancouver B2 type fractures: B2.1 (1 fractured zone) and B2.2 (≥2 fractured zones).

LEVEL OF EVIDENCE

Historical cohorts. Level III.

Mid- to long-term results of the Cone-Conical modular system in revision hip arthroplasty

BACKGROUND

Modular design in revision hip surgery allows some flexibility intra-operatively to address leg length discrepancy, version, and offset while allowing the surgeon to bypass a deficient proximal femur and achieve axial and rotational stability distally. The purpose of this study was to analyze the mid-term to long-term survival and clinical and radiological outcomes using a conical fluted stem and a cone-shaped hydroxyapatite-coated proximal body "The Cone-Conical modular system (Stryker)" in revision hip surgery.

METHODS

We retrospectively reviewed all the patients who underwent hip revision surgery using Cone-Conical modular system between January 2006 and January 2015 at our institution. Seventy patients (72 hips) were included with a mean age of 71.3 years. We had a mean follow-up period of 8.6 years (range 5-15). All patients had a minimum follow-up of five years. A Kaplan-Meier analysis was used to determine the survival of the implant. Functional outcomes were assessed using Oxford Hip Score. Plain radiographs were performed to assess implant fixation and osseointegration.

RESULTS

The mean OHS improved significantly from 12 pre-operatively to 34 at the final follow-up (P < .001). The Cone-Conical system survivorship for aseptic loosening as an end point was 100%. The all-cause survivorship was 97.2%. Two hips had revisions for recurrence of infection.

CONCLUSIONS

The Cone-Conical femoral modular revision system has demonstrated excellent mid-term to long-term clinical and radiographic results with low failure rate and minimal complications. Longer-term follow-up would be of value to assess the ongoing survival of this implant.

How Does Contact Length Impact Titanium Tapered Splined Stem Stability: A Biomechanical Matched Pair Cadaveric Study

BACKGROUND

Titanium tapered stems (TTS) achieve fixation in the femoral diaphysis and are commonly used in revision total hip arthroplasty. The initial stability of a TTS is critical, but the minimum contact length needed and impact of implant-specific taper angles on axial stability are unknown. This biomechanical study was performed to better guide operative decision-making by addressing these clinical questions.

METHODS

Two TTS with varying conical taper angles (2° spline taper vs 3.5° spline taper) were implanted in 9 right and left matched fresh human femora. The proximal femur was removed, and the remaining femoral diaphysis was prepared to allow for either a 2 cm (n = 6), 3 cm (n = 6), or 4 cm (n = 6) cortical contact length with each implanted stem. Stepwise axial load was then applied to a maximum of 2600N or until the femur fractured. Failure was defined as either subsidence >5 mm or femur fracture.

RESULTS

All 6 femora with 2 cm of stem-cortical contact length failed axial testing, a significantly higher failure rate (P < .02) than the 4 out of 6 femora and all 6 femora that passed testing at 3 cm and 4 cm, respectively, which were not statistically different from each other (P = .12). Taper angle did not influence success rates, as each matched pair either succeeded or failed at the tested contact length.

CONCLUSION

4 cm of cortical contact length with a TTS demonstrates reliable initial axial stability, while 2 cm is insufficient regardless of taper angle. For 3 cm of cortical contact, successful initial fixation can be achieved in most cases with both taper angle designs.

Periprosthetic Hip Fractures With a Loose Stem: Open Reduction and Internal Fixation Versus Stem Revision

BACKGROUND

It is recommended revision for periprosthetic hip fractures (PPHF) with a loose stem. However, several authors have argued that under certain conditions, this fracture could be treated using osteosynthesis. The aim is to compare stem revision versus internal fixation in the treatment of PPHF with a loose stem.

METHODS

All patients with PPHF with a loose stem treated by osteosynthesis and stem revision between January 2009 and January 2019 were included. We assessed hospital stay, American Society of Anesthesiologists, Charlson comorbidity index, surgery time, blood transfusion, complications, reoperation rate, first-year mortality, radiological, and functional results.

RESULTS

A total of 57 patients were included (40 osteosyntheses and 17 stem revision), with an average follow-up time of 3.1 years. Their mean age was 78.47 years (R 45-92). In the osteosynthesis group, fewer patients required blood transfusion (32.5% vs. 70.6%), surgical times were shorter (108 minutes vs. 169 minutes), and the cost was lower, both in terms of total cost (€14,239.07 vs. €21,498.45 and operating room cost (€5014.63 vs. €8203.34). No significant differences were found between the groups in terms of complications, reoperation rate, or functional outcomes.

CONCLUSION

Compared with stem revision, osteosynthesis requires less surgery time, has a lower need for blood transfusions, and a reduced hospital cost. Stem revision remains the treatment of choice in PPHF with a loose stem, but in V-B2 fractures in elderly patients with low functional demand, high anesthetic risk (American Society of Anesthesiologists ≥3), and many comorbidities (Charlson comorbidity index ≥5) in whom anatomic reconstruction is possible, osteosynthesis can be a viable option.

EVIDENCE LEVEL

Historical cohorts. Level III.

Mid- to Long-Term Outcomes of Cementless Modular, Fluted, Tapered Stem for Massive Femoral Bone Loss in Revision Total Hip Arthroplasty

OBJECTIVE

To evaluate mid- to long-term results of revision total hip arthroplasty for massive femoral bone loss using a cementless modular, fluted, tapered stem.

METHODS

This is a retrospective study performed at a single hospital. During the period of January 2007 to January 2015, 33 patients (34 hips) underwent primary revision surgery with cementless modular, fluted, tapered stems due to femoral bone loss. Sixteen men and 17 women were included in the study, with an average age of 63.9 ± 11.7 years (range, 27 to 88 years). Operative data including operative duration, length of incision, drainage volume and duration, blood loss and transfusion, cases of bone graft and extended trochanteric osteotomy were recorded. Clinical evaluation was performed using Harris hip score (HHS), visual analogue scale (VAS), and patients' satisfaction. Radiographic data including femoral stem fixation, subsidence, integrin of allograft bone, and leg length discrepancy were assessed. Complications and survivorship were evaluated using Kaplan-Meier survival rate.

RESULTS

The mean follow-up was 9.1 ± 2.5 years (range, 5-13 years). The Harris hip score was 43.6 ± 11.5 preoperatively and maintained at 86.5 ± 6.6 at the time of latest follow-up (P < 0. 05). The X-ray showed bone ingrowth fixation in 30 hips (88%), fibrous stable fixation in three hips (9%), and instability in one hip (3%). The average stem subsidence was 3.9 ± 2.2 mm (range, 1 to 10 mm). The mean difference in leg length in our study was 3.3 ± 2.7 mm (range, 0 to 10 mm), and the leg length discrepancy in 28 (82%) patients was within 5 mm. No case of junction fracture was observed. Seven (21%) intraoperative fractures occurred in our study. Three (9%) cases with infection were observed after revision. Six (18%) patients had lower limb vein thrombosis. The survivorship of prostheses with re-revision for any reason was 95% (95% CI, 12.0 to 13.0) at the 10-year follow-up. Three (9%) re-revisions were needed, including one for aseptic loosening, one for dislocation, and one for infection.

CONCLUSION

The mid- to long-term results of revision total hip arthroplasty with the cementless modular, fluted, tapered stems are encouraging for massive femoral bone loss.

Medium Term Radiographic and Clinical Outcomes Using a Modular Tapered Hip Revision Implant

Background

The rate of revision hip arthroplasty surgery is rising. Surgeons must use implants with proven outcomes to help overcome the technical challenges faced during revision surgery. However, outcome studies using these implants are limited. The aim of this study is to investigate the radiographic and clinical outcomes of the Stryker Restoration stem, the most commonly used hip revision stem in the United Kingdom (UK).

Methods

A retrospective review of a single surgeon case series was performed. Immediate postoperative radiographs were analyzed for offset and leg length discrepancy. Radiographic evidence of subsidence was assessed using follow-up radiographs. Kaplan-Meier survival analysis was applied using explantation and reoperation as endpoints. Patient-reported outcomes were measured using the Oxford Hip Score and EQ-5D-5L.

Results

One hundred ninety-eight cases were identified. Mean follow-up duration was 51.8 months (range: 24-121). Stem survival during this period was 98%. Reoperation for any reason was 13%. Mean subsidence was 4.18 mm. Analysis of variance testing showed no difference in mean subsidence between revision indications. Mean offset and leg length discrepancies were measured at 4.5 mm and 4.3 mm, respectively. The mean Oxford Hip Score for participants was 27.6.

Conclusions

This series demonstrates excellent implant survival, with radiographic parameters for reconstruction and subsidence levels comparable to those in the existing literature. The tapered modular hip revision stem provides surgeons with the intraoperative flexibility to overcome some of the anatomical difficulties encountered during revision surgery; this is reflected in the radiographic and clinical outcomes of the cohort in this study.

Revision Hip Arthroplasty Using a Porous-coated or Taper ZMR Implant: Minimum 10-year Follow-up of Implant Survivorship

INTRODUCTION

The Zimmer Modular Revision hip (ZMR) system is available in two stem options, a porous-coated cylindrical (PCM) and a taper (TM) stem. Several concerns have been reported regarding modular implants. Specifically, because of early junctional fractures, the ZMR system was redesigned with a wider modular interface. As such, we designed a study assessing long-term ZMR survivorship and functional and radiographic outcomes.

METHODS AND MATERIALS

A search of our institutional research database was performed. A minimum 10-year follow-up was selected. The following two cohorts were created: PCM and TM stems. The Kaplan-Meier survival analysis was performed, and causes of stem failure requiring revision surgery were collected. Functional outcomes as per the Harris Hip Score and radiographic stem stability were assessed as per the Engh classification.

RESULTS

A total of 146 patients meeting the inclusion criteria were available for follow-up (PCM = 68, TM = 78). The mean follow-up was 13.4 years clinically and 11.1 years radiographically for the PCM cohort. Similarly, the TM cohort had a follow-up of 11.1 years clinically and 10.5 years radiographically. The Kaplan-Meier survivorships were 87.1% and 87.8% at 15 years for the PCM and TM cohorts, respectively. The most common cause of failure requiring revision surgery overall was aseptic loosening (PCM = 1.4%, TM = 5.6%). The mean postoperative Harris Hip Score was as follows: PCM = 71.2 and TM = 64.7. Engh type I or II stem ingrowth was as follows: PCM = 85% and TM = 68%.

DISCUSSION

Good survivorship using the ZMR stem system can be expected at up to 15 years. Aseptic loosening remains the most commonly encountered problem for both PCM and TM stems. Previously identified modular junctional weakness seem to have been addressed.

Clinical, radiographic, and survivorship analysis of a modular fluted tapered stem in revision hip arthroplasty

PURPOSE

Modular fluted tapered stems are one of the most commonly used implants in femoral revision surgery. Due to the relative lack of studies on the Restoration modular fluted tapered stem, we conducted a study to evaluate its short- to mid-term clinical, radiographic, and survival outcomes.

METHODS

We identified all 45 patients treated with this revision stem at our institution. Five patients did not complete the minimum 2-year follow-up, leaving 40 patients (41 hips) for assessment. Mean follow-up was 5.1 years (range 2-11 years). Clinical outcomes were assessed using the Harris hip score (HHS). Radiographs were evaluated for subsidence and loosening. Kaplan-Meier survival analysis was performed using revision of the stem for any reason as end point.

RESULTS

The mean HHS improved from 44.6 points preoperatively to 78.4 points at the most recent follow-up (p < 0.0001). Nonprogressive subsidence occurred in 83% of the hips (mean 2.8 mm; range 1-7 mm). One stem (2.4%) showed progressive subsidence (20 mm) and was considered loose. The most common cause for reoperation was dislocation (three hips, 7.3%). The 10-year survivorship with revision of the stem for any reason as the end point was 93.5% (95% CI, 84.9-100%).

CONCLUSION

There was a significant improvement in the HHS and a low likelihood of revision at short- to mid-term follow-up, adding to the current evidence base for use of this implant in revision surgery. A longer follow-up and a larger number of cases are necessary to fully evaluate its role and performance.

Micromotion and subsidence of a cementless conical fluted stem depending on femoral defect size - A human cadaveric study

BACKGROUND

Cementless modular endoprostheses with tapered fluted stems cover a wide spectrum of femoral defects in reconstructive surgery of the hip. Nevertheless, for these hip stems the recommendations concerning the minimum diaphyseal anchorage distance differ widely. The present experimental study investigated the primary stability of a conical fluted revision stem depending on different types of femoral bone defects.

METHODS

Using six fresh frozen human femora, the relative movement of a bi-modular revision stem within the implant-bone interface was examined under cyclic loading conditions. Implant subsidence as well as micromotions at the bone-implant interface were captured with linear variable differential transformers for the intact femora and three different defects ranging from Paprosky type II to type IIIB.

FINDINGS

Compared to the intact femur, the infliction of a Paprosky type IIIB defect (3 cm of intact diaphysis) notably increased mean stem subsidence (13-389 μm per 500 load cycles; P = 0.116) but the mean interface micromotion vector sum remained unchanged (50 μm vs. 53 μm). In Paprosky IIIB defects the subsidence component resulting from rotation (horizontal plane) was significantly higher than with the intact femur and a Paprosky II defect (P ≤ 0.041).

INTERPRETATION

With optimal bone quality and ideal femur preparation a 3 cm conical fixation was sufficient to meet the set criteria of bony ingrowth in vitro. A conical fixation of 7 cm should be recommended to limit rotational subsidence, especially in case of impaired diaphyseal bone quality or expected difficulties with partial weight-bearing.

Single 3° tapered fluted femoral stems demonstrate low subsidence at mid-term follow-up in severe bony deficiency

Background

Tapered femoral stems have become popular in revision total hip arthroplasty (rTHA). Increasing the distal taper angle may mitigate subsidence. This study reports osseointegration of a new 3 degree distal taper revision stem at minimum 4 years post-operatively.

Methods

Indication for surgery, pre-operative bony deficiency and latest clinical, tribological and radiological follow-up were analysed. Radiographs were assessed by two blinded observers for preoperative femoral bone stock according to Paprosky, postoperative subsidence according to Callaghan and restoration of femoral bone stock over time according to Kolstad. Stem integration was determined using the Rodriguez classification.

Results

Twenty-three cases were analyzed at 5.9±1.0 years. All patients presented with Paprosky III defects. All stems met the criteria for osseointegration. Spot welds occurred distal to the proximal modular junction and at the tip. Two femora with severe proximal femoral bone loss recovered bone stock by final follow-up but two demonstrated stress shielding. No intraoperative fractures occurred. One stem subsided early but remained stable and osseointegrated at final follow up. There were no stem failures due to taper corrosion or modular junctional failure.

Conclusions

This study reports good osseointegration and low subsidence with a novel fluted, 3-degree tapered femoral stem demonstrates at medium-term follow-up in cases with severe femoral bone deficiency.

Femoral stem modularity

Femoral stem modularity in hip replacement was first developed to connect a ceramic head to the stem, then extended to metal heads using the Morse taper principle. Is it a good thing, or a necessary evil? It contributes to improving lower limb length and lateralization setting, at the cost of fairly rare complications such as dissociation and fretting corrosion, which can exceptionally lead to ARMD (Adverse Reaction to Metal Debris). Modular necks were later recommended, with a double Morse taper: cylindrical for the head junction, and more or less flattened for the stem. Is this one modularity too far? Dual modularity in theory perfectly reproduces the biomechanical parameters of the hip, but is unfortunately associated with fractures and severe corrosion, leading to ARMD and pseudotumor, especially in Cr-Co necks. Moreover, it provides no functional advantage, and no longer has a role outside dysplasia and other femoral deformities. Metaphyseal-diaphyseal modularity is not widespread in primary implants, and is it really necessary? Only one model has been widely studied: S-Rom™ (Depuy®). It features a metaphyseal sleeve adapting to the anatomy of the proximal femur, with a stem fitted via an inverse Morse taper. Its only interest is in case of congenital dislocation; like all metal connections, it incurs a risk of fracture and corrosion. On the other hand, modularity is widely employed in revision implants. Does it really help these procedures? The connection between a proximal femoral component of variable geometry and a diaphyseal stem with press-fit distal fixation provides a real solution to problems of length, lateralization and anteversion. Early models encountered high rates of fracture, but current implants and rigorous surgical technique have reduced this risk. Corrosion is a less serious problem, as the Morse taper undergoes only axial stress, without the friction undergone by other models subject to varus stress.

Cementless One-Stage Revision in Chronic Periprosthetic Hip Joint Infection. Ninety-One Percent Infection Free Survival in 56 Patients at Minimum 2-Year Follow-Up

BACKGROUND

Cementless 1-stage revision in chronic periprosthetic hip joint infections is limited evaluated. The purpose of this study was to evaluate a specific treatment protocol in this patient group.

METHODS

The study was performed as a multicenter, proof-of-concept, observational study with prospective data collection. Patients were treated with a cementless 1-stage revision according to the CORIHA protocol between 2009 and 2014. Fifty-six patients, McPherson type III-A/B-1/2, were enrolled with a mean follow-up time from the CORIHA procedure of 4 years (minimum of 2 years). The primary outcome was re-revision performed due to infection and was evaluated by competing risk analysis, with death and aseptic revision as competing events. All-cause mortality was evaluated by Kaplan-Meier survival analysis. Oxford Hip Score (OHS) was used as disease-specific patient-reported outcome measure.

RESULTS

The cumulative incidence of re-revision due to infection was 8.9% (confidence interval [CI] 3.2%-18.1%). The 1-year and 5-year survival incidence was 96% (CI 86%-99%) and 89% (CI 75%-95%). OHS at baseline was 19.9 (CI 17.3-22.6) and at 24-month follow-up 35.1 (CI 31.7-38.5). The mean change in OHS from baseline to 24-month follow-up was 11.8 points (CI 7.3; 16.3). Three patients had aseptic revision performed: two suffered periprosthetic fractures and one had stem subsidence. Failure analysis of the 5 reinfections did not detect a clear pattern as to the cause of failure.

CONCLUSION

We found that cementless 1-stage revision in chronic periprosthetic hip joint infections has low reinfection rates in selected patients and may be applicable as a first-line treatment.

Nano-carrier based drug delivery systems for sustained antimicrobial agent release from orthopaedic cementous material

Total joint replacement (TJR), such as hip and knee replacement, is a popular procedure worldwide. Prosthetic joint infections (PJI) after this procedure have been widely reported, where treatment of such infections is complex with high cost and prolonged hospital stay. In cemented arthroplasties, the use of antibiotic loaded bone cement (ALBC) is a standard practice for the prophylaxis and treatment of PJI. Recently, the development of bacterial resistance by pathogenic microorganisms against most commonly used antibiotics increased the interest in alternative approaches for antimicrobial delivery systems such as nanotechnology. This review summarizes the efforts made to improve the antimicrobial properties of PMMA bone cements using nanotechnology based antibiotic and non-antibiotic delivery systems to overcome drawbacks of ALBC in the prophylaxis and treatment of PJIs after hip and knee replacement.

Locking compression plate versus revision-prosthesis for Vancouver type B2 periprosthetic femoral fractures after total hip arthroplasty

INTRODUCTION

Revision arthroplasty is currently the recommended treatment for periprosthetic femoral fractures after primary total hip arthroplasty (THA) and stem loosening (Vancouver B2). However, open reduction and internal fixation (ORIF) utilizing locking compression plate (LCP) might be an effective treatment with a reduced surgical time and less complex procedure in a typically elderly patient collective with multiple comorbidities. The purpose of this study was to compare the functional and radiographic outcomes in two cohorts with Vancouver B2 periprosthetic femoral fractures after primary THA, treated either by ORIF with LCP fixation, or by revision arthroplasty utilizing a non-cemented long femoral stem.

MATERIALS AND METHODS

36 patients with Vancouver B2 periprosthetic femoral fractures following THA, who had been treated between 2000 and 2014, were reviewed. Eight fractures were treated with LCP fixation, fourteen fractures with the first-generation revision prosthesis (Helios), and fourteen fractures with the second-generation revision prosthesis (Hyperion). The patients were assessed clinically with the Parker mobility score and radiographically.

RESULTS

A total of ten males and 26 females formed the basis of this report with an average age of 81 years (range, 64 to 96 years). All fractures treated with LCP fixation alone healed uneventfully and there were no signs of secondary stem migration, malalignement or plate breakage. The average surgical time was shorter in the ORIF cohort; however, the results were not statistically significant. The postoperative Parker mobility score at latest follow-up showed no difference between the groups.

CONCLUSIONS

According to the results of the current study, we conclude that the use of LCP fixation can be a sufficient option for the treatment of Vancouver B2 periprosthetic femoral fractures correspondingly with femoral stem loosening.

An In Vitro Comparison of the Primary Stability of 2 Tapered Fluted Femoral Stem Designs

BACKGROUND

Proximal bony deficiencies present a biomechanical challenge to achieving primary stability in revision hip arthroplasty. Long tapered fluted stems have been engineered to span these defects but concerns of early subsidence are well documented. This work aimed primarily to investigate the issue of subsidence with this design using a cadaveric model. A secondary aim was to compare the stability of 2 versions of this design.

METHODS

Seven pairs of cadaveric femora were obtained, dual emission x-ray absorpitometry scanned, with calibration radiographs taken for digital templating. Each bone was potted according to the ISO standard for fatigue testing and a Paprosky type 3 defect was simulated. The established cone-conical Restoration Modular (Stryker) system and a novel design with a chamfered tip and flute configuration (Redapt, Smith & Nephew) were examined. Movement at the stem-bone interface was measured using radiostereometric analysis and micromotion transducers.

RESULTS

All restoration stems and 85% of the Redapt stems achieved stability by recognized criteria, micromotion < 150 μm and migration less than 2 mm. A Fisher exact test comparing the proportion of stems which were stable or unstable was not significant, P = .055. Mean axial subsidence (SD) was 0.17 mm (0.32) and 0.1 mm (0.131) for the Restoration and Redapt stems respectively.

CONCLUSION

This study has demonstrated minimal subsidence in the immediate post-operative period using tapered fluted stems. Both designs achieved excellent stability despite simulation of Paprosky type 3 bony defects in the cadaveric model. This geometry appears satisfactory for use in revision surgery in the presence of significant proximal bony deficiencies.

Midterm Outcomes of Revision Total Hip Arthroplasty Using a Modular Revision Hip System

BACKGROUND

The growth in hip arthroplasty surgery has meant a corresponding escalating revision burden with increasing challenges for the orthopaedic surgeon. The purpose of this study was to review clinical outcomes of a modular revision hip system within a single institution.

METHODS

We retrospectively reviewed a cohort of modular revision hip system stems performed in our institution between January 2005 and October 2012 giving a potential minimum follow-up of 2 years. Clinical outcomes data on complications, Oxford Hip Score (OHS, 0-48) and patient satisfaction were collected. Radiographic outcomes including subsidence were assessed. Implant survival was estimated using Kaplan Meier analysis.

RESULTS

115 stems in 106 patients were identified. All cause survival was 82% (95%CIs: 73%-89%) at 6.1 years; survival excluding infection being 99% (95%CIs: 93%-100%). There was a low incidence of subsidence (seven stems) and no peri-prosthetic fractures. Primary cause of re-revision in this series was re-infection with only one re-revision for mechanical failure. Median Oxford Hip Score at mean follow up 4.1 years (2-9) was 40 (14-48) and 93% of patients reported being satisfied with their revision surgery.

CONCLUSION

This study showed good clinical outcomes and survival using a modular revision stem with low mechanical failure and subsidence. Recurrence of infection remains a challenge in revision surgery.

Outcomes of Mixed Femoral Fixation Technique Using Both Cement and Ingrowth in Revision Total Hip Arthroplasty: Minimum 2-Year Follow-up

The use of a modular femoral stem in revision total hip arthroplasty (THA) has been increasing recently. However, complications such as subsidence, dislocation and stem fracture are still noted, especially in hips with high grade femoral deficiency. We retrospectively studied a consecutive 41 hips (40 patients) that underwent revision THA with allograft reconstruction of the proximal femur in conjunction with hybrid fixation (proximally cemented and distally press-fit) of a modular femoral component. At a mean follow-up of 5.2 years (2 to 8 years), no hips sustained dislocation, subsidence or fracture of the stem in the follow-up period. We provided evidence that this technique may be a good alternative in the management of proximal femoral bone loss during revision THA.

The Effect of Taper Angle and Spline Geometry on the Initial Stability of Tapered, Splined Modular Titanium Stems

Design parameters affecting initial mechanical stability of tapered, splined modular titanium stems (TSMTSs) are not well understood. Furthermore, there is considerable variability in contemporary designs. We asked if spline geometry and stem taper angle could be optimized in TSMTS to improve mechanical stability to resist axial subsidence and increase torsional stability. Initial stability was quantified with stems of varied taper angle and spline geometry implanted in a foam model replicating 2cm diaphyseal engagement. Increased taper angle and a broad spline geometry exhibited significantly greater axial stability (+21%-269%) than other design combinations. Neither taper angle nor spline geometry significantly altered initial torsional stability.

Periprosthetic fractures: bespoke solutions

We are currently facing an epidemic of periprosthetic fractures around the hip. They may occur either during surgery or post-operatively. Although the acetabulum may be involved, the femur is most commonly affected. We are being presented with new, difficult fracture patterns around cemented and cementless implants, and we face the challenge of an elderly population who may have grossly deficient bone and may struggle to rehabilitate after such injuries. The correct surgical management of these fractures is challenging. This article will review the current choices of implants and techniques available to deal with periprosthetic fractures of the femur.

The management of type B1 periprosthetic femoral fractures: when to fix and when to revise

The incidence of periprosthetic fractures around total hip arthroplasty is increasing as patient longevity rises and the number of patients with hip implants continues to grow. Type B1 periprosthetic femoral fractures are associated with a well-fixed stem and have traditionally been treated with internal fixation. However, there are a subset of these fractures which fare badly when internal fixation is undertaken, and revision of the femoral component to a long-stemmed implant may be more appropriate. We look at the traditional methods of fixation, and the evidence and indications for revision of these fractures.

Uncemented femoral revision arthroplasty using a modular tapered, fluted titanium stem: 5- to 16-year results of 163 cases

BACKGROUND AND PURPOSE

Due to the relative lack of reports on the medium- to long-term clinical and radiographic results of modular femoral cementless revision, we conducted this study to evaluate the medium- to long-term results of uncemented femoral stem revisions using the modular MRP-TITAN stem with distal diaphyseal fixation in a consecutive patient series.

PATIENTS AND METHODS

We retrospectively analyzed 163 femoral stem revisions performed between 1993 and 2001 with a mean follow-up of 10 (5-16) years. Clinical assessment included the Harris hip score (HHS) with reference to comorbidities and femoral defect sizes classified by Charnley and Paprosky. Intraoperative and postoperative complications were analyzed and the failure rate of the MRP stem for any reason was examined.

RESULTS

Mean HHS improved up to the last follow-up (37 (SD 24) vs. 79 (SD 19); p<0.001). 99 cases (61%) had extensive bone defects (Paprosky IIB-III). Radiographic evaluation showed stable stem anchorage in 151 cases (93%) at the last follow-up. 10 implants (6%) failed for various reasons. Neither a breakage of a stem nor loosening of the morse taper junction was recorded. Kaplan-Meier survival analysis revealed a 10-year survival probability of 97% (95% CI: 95-100).

INTERPRETATION

This is one of the largest medium- to long-term analyses of cementless modular revision stems with distal diaphyseal anchorage. The modular MRP-TITAN was reliable, with a Kaplan-Meier survival probability of 97% at 10 years.

Revision total hip arthroplasty with modular femoral stems

As the rate of revision total hip arthroplasty (THA) rises, attention must be paid to potential complications relating to bone loss, soft tissue deficiencies, and loss of tissue planes. Using modular femoral stems in revision surgery allows for varying amounts of bone loss in the proximal and distal femur while letting the surgeon adjust rotation, leg length, and offset. We retrospectively reviewed 125 patients that underwent revision THA with a modular femoral component system and had minimum 2 year follow-up. Ten patients required reoperations for infection, recurrent dislocation, or fracture treatment. There was no evidence of radiographic loosening or mechanical failure in the remaining patients. Modular femoral components provide excellent intraoperative flexibility and significant radiographic and clinical benefits as seen in this patient cohort.

Proximal femoral arthroplasty in patients undergoing revision hip arthroplasty

Bone loss represents one of the greatest challenges in revision joint surgery. A retrospective review was conducted of both radiographic and clinical outcomes of eleven patients who underwent revision arthroplasty using a long extensively porous coated cylindrical femoral component. All patients' femurs presented with severe proximal femoral bone loss (Paprosky class IIIB and IV). With a mean follow-up of 8 years (2 to 14) we report no femoral revisions and one acetabular revision to a constrained cup secondary to instability. All patients were clinically and radiographically stable. We did not observe any issue with proximal stress shielding or component loosening. The article reports that in patients with severe proximal femoral bone loss, extensively porous-coated non-modular stems are a viable option offering stable and predictable outcomes.

Reproducible fixation with a tapered, fluted, modular, titanium stem in revision hip arthroplasty at 8-15 years follow-up

The use of tapered, fluted, modular, distally fixing stems has increased in femoral revision surgery. The goal of this retrospective study was to assess mid-term to long-term outcomes of this implant. Seventy-one hips in 70 patients with a mean age of 69 years were followed for an average of 10 years. Preoperative HHS averaged 50 and improved to 87 postoperatively. Seventy-nine percent hips had Paprosky type 3A or more bone-loss. All stems osseointegrated distally (100%). Two hips subsided >5mm but achieved secondary stability. Sixty-eight percent hips had evidence of bony reconstitution and 21% demonstrated diaphyseal stress-shielding. One stem fractured near its modular junction and was revised with a mechanical failure rate of 1.4%. Distal fixation and clinical improvement were reproducibly achieved with this stem design.

Medium-term outcomes of cemented prostheses and cementless modular prostheses in revision total hip arthroplasty

There is an increasing trend towards cementless modular femoral prostheses for revision hip replacement surgery, especially in patients with severe proximal femoral bone defects. However, for minor femoral bone defects, the benefit of cementless modular is not clear. We designed a retrospective cross-sectional study to compare outcomes of the two femoral implant designs. There were no significant differences in terms of visual analog pain scores, Harris hip scores, femoral bone restoration, stem subsidence, leg length correction, or overall complication rate. Three femoral reoperations (11%) occurred in the cemented group, and two (9%) in the cementless modular group. One femoral stem re-revised (4%) in the cemented group due to recurrent deep infection. Five-year survival for femoral reoperation was 88.2% for patients with the cemented implant and 91.3% for cementless group. Both groups had good clinical and radiological outcomes for femoral revision in patients with minor femoral bone defects during medium-term follow-up.

Limited slot femorotomy for removal of proximally coated cementless stems. A 10-year follow-up of an unreported surgical technique

We present a technique of single posterior longitudinal slot femorotomy. This technique allows the expansion of the metaphyseal-diaphyseal region of the proximal femur facilitating extraction of proximally coated uncemented femoral components while leaving the metaphysis and diaphysis intact. Since 1996 we have performed this technique in 18 revision total hip arthroplasties in 15 patients who had x-ray appearance of bony in-growth/on-growth and where found to have solidly ingrown stems at revision surgery. All were revised to a metaphyseally fitting uncemented stem. At mean follow-up of 122.4 months, there were significant improvements in both pain and function. All revised stems achieved stable boney fixation. There were no complications due to this technique. No patient developed a limp or thigh pain postoperatively. There have been no re-revisions of the stem. With appropriate patient selection, this is a simple, reliable, and extensile technique is useful to assist in the extraction of uncemented proximally coated femoral components whether hydroxyapatite-coated or not.

Leg-length discrepancy after revision hip arthroplasty: are modular stems superior?

We retrospectively reviewed data for 79 consecutive patients who underwent revision hip arthroplasty using cementless femoral stems at our center between September 2008 and November 2010. Two cohorts were included, one using MP (modular) femoral stems and the other using Wagner (monoblock) femoral stems. We assessed leg-length discrepancy (LLD) before and after revision and compared the occurrence of leg-length inequality between the 2 cohorts. We found that the incidence of LLD was high in revision hip arthroplasty and that leg shortening was more common than lengthening. Both acetabular and femoral sides contributed to postoperative LLD. Appropriate placement of the femoral components was most critical in adjusting LLD. We also found that compared with monoblock stems, modular stems made adjustment of postoperative leg length easier.

Three to seven year follow-up of a tapered modular femoral prosthesis in revision total hip arthroplasty

PURPOSE

Modular femoral prostheses can provide independent distal fixation and intraoperative flexibility and are being used increasingly, especially in patients with proximal femoral bone defects. This retrospective clinical study evaluated whether modular prostheses were effective and reliable implants for femoral revision.

METHOD

This case series consisted of 58 patients who underwent hip revision with a tapered modular femoral prosthesis at our institution between 2004 and 2008. Mean patient age at surgery was 64 years (range 18-86 years). Femoral bone defects before revision surgery were evaluated using the Paprosky classification. All patients were followed for a minimum of 3 years (mean 4.3 years, range 3-7 years) with clinical and radiographic evaluation. Re-revisions and complications were also recorded.

RESULTS

Two stems required re-revision, one each for recurrent deep infection and periprosthetic fracture. At last follow-up, the Harris Hip Score and Visual Analog Pain Scores had improved significantly, the median radiographic stem migration was 1.6 mm, leg length discrepancy was corrected in 64 % of the patients and osseointegration occurred in 90 %. Complications included intraoperative fracture in 10 (17 %) patients and hip dislocation in 2 (3 %).

CONCLUSION

Modular femoral components can improve hip function, provide distal fixation, equalize leg length, and result in fewer complications when used to revise failed femoral components.

A financial analysis of revision hip arthroplasty: the economic burden in relation to the national tariff

Revision arthroplasty of the hip is expensive owing to the increased cost of pre-operative investigations, surgical implants and instrumentation, protracted hospital stay and drugs. We compared the costs of performing this surgery for aseptic loosening, dislocation, deep infection and peri-prosthetic fracture. Clinical, demographic and economic data were obtained for 305 consecutive revision total hip replacements in 286 patients performed at a tertiary referral centre between 1999 and 2008. The mean total costs for revision surgery in aseptic cases (n = 194) were £11 897 (sd 4629), for septic revision (n = 76) £21 937 (sd 10 965), for peri-prosthetic fracture (n = 24) £18 185 (sd 9124), and for dislocation (n = 11) £10 893 (sd 5476). Surgery for deep infection and peri-prosthetic fracture was associated with longer operating times, increased blood loss and an increase in complications compared to revisions for aseptic loosening. Total inpatient stay was also significantly longer on average (p < 0.001). Financial costs vary significantly by indication, which is not reflected in current National Health Service tariffs.

Is there a learning curve in foot and ankle surgery?

BACKGROUND

Previous studies of orthopaedic learning curves have largely described the introduction of new techniques to experienced consultants. End points have usually involved technical considerations. A paucity of evidence surrounds foot and ankle surgery. This study investigates the learning curve during a foot and ankle surgeon's first year, defined by functional outcome.

METHODS

150 patients underwent elective foot or ankle surgery during the whole period. Preoperative and 6 month postoperative functional scores were compared between the first and second 6 month groups.

RESULTS

Functional improvement was greater, approaching significance, in the second group (p=0.0605). There was no difference for forefoot cases (p=0.345). Functional improvement was significantly greater in the second group with forefoot cases removed (p=0.0333).

CONCLUSIONS

A learning curve exists in the first year of practice of foot and ankle surgery, demonstrated by functional outcome. This is confined to ankle, hindfoot and midfoot, but not forefoot surgery.