Interprosthetic femoral fractures-A challenge of treatment. A systematic review of the literature

The History of Classification Systems for Periprosthetic Femoral Fractures: A Literature Review

Periprosthetic femoral fractures (PPFFs) following total hip arthroplasty (THA) present a significant clinical challenge due to their increasing incidence with an aging population and evolving surgical practices. Historically, classifications were primarily based on anatomical fracture location, the stability of the implant, and bone quality surrounding the implant. We critically analyzed 25 classification systems, highlighting the emergence and adaptations of key systems such as the Vancouver classification system (VCS) and the Unified classification system (UCS), which are lauded for their simplicity and effectiveness yet require further refinement. VCS, developed in 1995, categorizes fractures based on the site, implant stability, and bone quality, and remains widely used due to its robust applicability across different clinical settings. Introduced in 2014, UCS expands the VCS to encompass all periprosthetic fractures with additional fracture types, aiming for a universal application. Despite their widespread adoption, these systems exhibit shortcomings, including the incomplete inclusion of all PPFF types and the imprecise assessment of implant stability and surrounding bone loss. These gaps can result in misclassification and suboptimal treatment outcomes. This paper suggests the necessity for ongoing improvements in classification systems to include emerging fracture types and refined diagnostic criteria, ensuring that they remain relevant to contemporary orthopedic practices and continue to facilitate the precise tailoring of treatment to patient-specific circumstances. This comprehensive historical review serves as a foundation for future innovations in classification systems, ultimately aiming to standardize PPFF treatment and improve patient prognosis.

High Rate of Unplanned Reoperation for Interprosthetic Femur Fractures After Total Hip and Knee Arthroplasty

BACKGROUND

Interprosthetic femur fractures (IPFFs) are a rare, but devastating complication following total joint arthroplasty. There is limited evidence to help guide their management. The purpose of this study was to describe the features, treatment, and outcomes of surgically managed IPFFs.

METHODS

We retrospectively identified 75 patients who had 76 IPFFs. The mean age at the time of IPFF was 75 years (range, 29 to 94), and 78% were women. The mean body mass index was 30 (range, 19 to 51), and the mean follow-up was 3 years (range, 0 to 14). There were 16 Vancouver B1 fractures, 28 Vancouver B2 fractures, 2 Vancouver B3 fractures, and 30 Vancouver C fractures. All B1 fractures underwent open reduction internal fixation (ORIF). All Vancouver B2 and B3 fractures underwent revision arthroplasty, including 1 proximal femur replacement and 1 total femur replacement. Vancouver C fractures were treated with ORIF (n = 20), distal femoral replacement (n = 9), and in 1 case, total femur replacement (n = 1). Kaplan-Meier survivorship was used to calculate 2-year survival free from all-cause reoperation and periprosthetic joint infection (PJI).

RESULTS

The 2-year survivorship-free rate from reoperation was 71%. There were 18 reoperations following initial surgical management of the IPFF, including 9 for infection, 3 for refracture, 3 for nonunion, 2 for hardware failure, and 1 for instability. An initial IPFF involving a stemmed femoral total knee arthroplasty component was associated with increased risk for reoperation (P = .007) and PJI (P = .044). There was no difference in survivorship free of reoperation between IPFFs managed with ORIF or revision arthroplasty (P = .72).

CONCLUSIONS

An IPFF is a devastating complication following total joint arthroplasty with high reoperation rates, most commonly secondary to PJI. Those IPFFs that occurred between 2 stemmed components were at the highest risk for reoperation.

Interimplant femoral fracture: analysis of risk factors

Interimplant fractures present a significant challenge for orthopedic surgeons. Despite a noticeable rise in these cases in recent years, our understanding of this specific fracture type remains limited. This study aims to analyze and identify the primary risk factors associated with interimplant femoral fractures. We conducted a retrospective analysis involving 20 patients with interimplant femoral fracture (case group) and 18 patients who had both proximal and distal femoral implants but did not experience interimplant fractures (control group). Our analysis focused on demographic factors (age, sex, BMI) and radiographic parameters (implant types, gap between implants, cortical thickness, femoral canal area) to identify potential risk factors. In the case group, all patients were females, whereas in the control group, 16 patients were female and 2 were males. The mean age in the case group was 88 [Formula: see text] 9 years and in the control group was 87 [Formula: see text] 12 years. None of the demographic differences reached statistical significance. The mean cortical thickness in the case group was 6 [Formula: see text] 2.25 mm, whereas in the control group, it was 9 [Formula: see text] 1.75 mm (p-value < 0.001). The median gap between the proximal and distal tips of the implants measured 194 [Formula: see text] 126 mm in the case group and 66 [Formula: see text] 78 mm in the control group (p-value < 0.001). Additionally, the mean femoral canal area was 284 [Formula: see text] 102 mm2 in the case group and 227 [Formula: see text] 26 mm2 in the control group (p-value < 0.010). Our data indicate that a small cortical thickness, a wide femoral canal area, and having a hip arthroplasty despite a gap between the implants exceeding 110 mm are factors that elevate the risk of interimplant femoral fracture. Notably, osteoporosis therapy emerges as a protective factor against these fractures.

Incidences and Outcomes of Operatively Treated Interprosthetic Femoral Fractures Compared to Vancouver Type C and Rorabeck Type II Fractures

BACKGROUND

This case-control study evaluated the incidences and outcomes of interprosthetic femoral fracture (IPFF) (Group I) and performed comparisons with Vancouver type C (Group II) and Rorabeck type II (Group III) periprosthetic femoral fractures (PPFF) occurring at similar anatomic sites.

METHODS

A retrospective analysis was performed for all patients who had a previously implanted total hip arthroplasty (THA) and total knee arthroplasty (TKA), who lived in the hospital district and had undergone surgery due to PPFF. A total of 153 PPFFs [Group I (n = 31), Group II (n = 21), and Group III (n = 108)] were included. The annual incidences of PPFFs were summarized per 100,000 individuals. The risks of complications, reoperations, and mortalities were evaluated for all groups.

RESULTS

The mean population-based annual incidence was 0.9 per 100,000 person years for Group I, 0.7 per 100,000 person years for Group II, and 3.1 per 100,000 person years for Group III. A total of 25 of 153 (16%) major complications were found and 23 of 153 (13%) cases resulted in a revision surgery. The cumulative incidence of death in Group I was 50.4% at 10 years, in Group II it was 63.8% at 10 years, and in Group III it was 74.9% at 10 years.

CONCLUSION

The annual incidence of the IPFF almost doubled while the incidence of Vancouver type C stayed stable and Rorabeck type II incidence increased 5-fold. Most of the major complications occurred in IPFF group, while Rorabeck type II patients had the worst survival.

[Treatment aspects of interprosthetic femur fractures-retrospective analysis of 70 patients]

BACKGROUND

Interprosthetic femur fractures (IFF) are rare injuries, whose surgical treatment is basically with osteosynthesis or revision arthroplasty. Various therapy algorithms have been proposed based on very small study collectives. Factors influencing the outcome are not known.

OBJECTIVES

The aim of the retrospective monocentric study is to derive a treatment algorithm based on a large number of cases and to identify factors influencing the outcome.

MATERIALS AND METHODS

Between 2006 and 2020, 70 IFF were identified. The surgical treatment comprised 38 osteosyntheses, 30 revision arthroplasties and 2 amputations. With classification and time to surgery, 69 perioperative variables were recorded. General and operative complications, as well as mortality, were determined in the follow-up period of 1 year.

RESULTS

ASA and Charlson score correlated with 1‑year-mortality. In addition, preoperatively increased CRP levels, reduced hemoglobin and the CHA2DS2-VASc score were identified as factors influencing mortality. Surgery within 24 h showed a trend towards fewer general complications. Transferred patients indicated an increased mortality. Based on classification according to Pires et al. or Füchtmeier et al. no clear treatment decision could be made. Relevant criteria for the surgical treatment were fracture localization, implant stability, bone vitality, anchoring possibility of the revision stem, as well as general condition of the patient.

CONCLUSIONS

The identified factors influencing the outcome correspond to those of patients with hip fractures. IFF should be treated timely. A treatment path was developed on the basis of the largest patient group to date.

A Novel Approach to Treat a Rare Case of Interprosthetic Humeral Fracture with Osteosynthesis and Combined Grafting: A Case Report and Review of the Literature

Interprosthetic humeral fractures (IHFs) are severe injury patterns associated with surgical issues and contradictory results. The knowledge and literature on this topic are still lacking. A 76 year-old woman was treated for a fracture occurred between the shoulder and elbow stemmed prosthesis. Severe bone loss was associated with the fracture. Treatment: Open reduction, plate fixation, and bone grafting were considered. A xenograft (used as a mechanical strut medially), a synthetic graft associated with bone growth factors, and scaffolds improved the bone healing process. Satisfactory clinical and radiological outcomes were obtained. A scoping review of the literature was also performed by the authors. Only eight papers reported IHFs with a low level of evidence. In total, eight patients were treated; one paper that reported on biomechanical aspects using finite element analysis is discussed. Conservative treatment leads to non-union, and the surgical approach is the gold standard. The osteosynthesis technique associated with bone grafting leads to the best outcomes. The use of a xenograft mechanical strut, associated with synthetic biological bone grafting, led to complete bone union at 9 months follow-up. Larger cohorts, more standardised results, and multicentric studies are mandatory in order to improve and establish a management and treatment algorithm.

Interprosthetic and interimplant femoral fractures: is bone strut allograft augmentation with ORIF a validity alternative solution in elderly?

BACKGROUND

Nowadays orthopedic surgeons have a new challenge to treat the interimplants fractures. Although fixation strategies exist for periprosthetic hip and knee fractures, there is no standard of care regarding the more complex interprosthetic and interimplants fractures.

OBJECTIVE

The aim of our study is targeting the focus on the bone strut grafting to avoid the metal hardware failure and to achieve the bone healing in these injuries.

METHODS

A prospective case note review of all interprosthetic or interimplants femoral fractures admitted to our trauma center. There were 11 patients (2 males and 9 females) with a mean age over 85 years old. We treated all the patients by ORIF and medial graft strut allograft to reduce the main complication leading to re-operations and morbidity or mortality is the nonunion or delayed union. The criteria to evaluate the patients during the follow-up were: the survival and complication after the surgery; the objective quality of life measured by Activities of Daily Living Score (ADL). The bone healing was measured by X-rays control as the alignment was measured by radiographic UNION SCORE, and postoperative complications.

RESULTS

All the patients reduced their ADL. In the most of cases we had a good x-rays reduction. We had not: No nonunion or Not delayed union. All patients died within 2 years from the surgery but not due by surgical complications.

CONCLUSIONS

According us, the purpose of this surgery is to limit comorbidities and early mortality not to improve optimal restoration of lower limb function.

A systematic review of the surgical outcomes of interprosthetic femur fractures

Background

Interprosthetic femur fractures (IFFs) are rare, but the treatment is challenging. Currently, there are many treatment methods used in practice, but an updated systematic review of comparison of common different surgical outcomes has not been thoroughly inspected.

Methods

A systematic review of retrospective studies was conducted. The resource databases of PubMed, Cochrane, and Embase were searched using a combination of the keywords involving IFFs and surgical outcomes from inception through June 2021. Data collected included patient demographics, intraoperative data, and postoperative outcomes. Outcomes were measured based on healing time, revision rate, complication rate, and functional scores.

Results

Forty studies were included for review with a total of 508 patients. Average reported age of patients was 78.7 years old and 403 (79.3%) were females. Overall union rate was 74.0% with 376 of 508 patients achieving fracture union after primary treatment of IFF. Only 271 patients had reported healing times of fractures with a mean of 5.15 months. The plate, prosthetic revision, nail/rod, and external fixator groups had mean healing times of 4.69, 8.73, 6.5, and 5.1 months, respectively. Revision rates were highest in the femur replacement treatment group with 9 (32.1%) patients needing at least one reoperation surgery for any reason. Overall, hardware failure and non-unions were the most reported complications in treatment of IFFs. Postoperative functional outcome scores were available for 242 patients. Harris Hip Scores for the plate, revision, replacement, nail/rod, and plate + revision groups were 76.84, 77.14, 69.9, 77, and 78.4, respectively.

Conclusion

Each treatment method should be carefully considered by the surgeon depending on the patient. Locking plate was the most common method for the treatment of the patients with IFFs. Half of them combined with cerclage wires/cables. Around two thirds' patients could achieve union with the fastest mean healing time around 4.69 months. Other less common methods included prosthetic revision, femur replacement, nail/rod, external fixator, etc. A small number of patients treated with Ilizarov external fixator, and it has proven to be a viable option with few complications and high union rates.

Interprosthetic Femur Fractures: A Review Article

➢

The prevalence of interprosthetic femur fractures (IFFs) is rising with the aging population and increased prevalence of total joint arthroplasty.

➢

IFFs have high rates of complications and high associated morbidity and mortality.

➢

The main treatment methods available for IFFs include plate fixation, intramedullary nailing, combined plate fixation and intramedullary nailing, and revision arthroplasty including partial and total femur replacement.

➢

There have been several proposed classification systems and at least 1 proposed treatment algorithm for IFFs; however, there is no consensus.

➢

Whichever treatment option is chosen, goals of surgery should include preservation of blood supply, restoration of length, alignment, rotation, and sufficient stabilization to allow for early mobilization.

Treatment Algorithm of Periprosthetic Femoral Fracturens

Introduction. The ever-expanding indications for total hip arthroplasty are leading to more implants being placed in younger as well as in older patients with high functional demand. Also, prolonged life expectancy is contributing to an overall increment of periprosthetic femoral fractures. The Vancouver classification has been the most used for guiding the surgeon choice since its proposal in 1995. Fractures occurring over a hip femoral implant can be divided into intra-operative and post-operative PFFs, and their treatment depends on factors that may severely affect the outcome: level of fracture, implant stability, quality of bone stock, patients' functional demand, age and comorbidities, and surgeon expertise. There are many different treatment techniques available which include osteosynthesis and revision surgery or a combination of both. The goals of surgical treatment are patients' early mobilization, restoration of anatomical alignment and length with a stable prosthesis and maintenance of bone stock. Significance. The aim of this review is to describe the state-of-the-art treatment and outcomes in the management of PFFs. We performed a systematic literature review of studies reporting on the management of PFFs around hip stems and inter-prosthetic fractures identifying 45 manuscripts eligible for the analysis. Conclusions. PFFs present peculiar characteristic that must be considered and special features that must be addressed. Their management is complex due to the extreme variability of stem designs, the possibility of having cemented or uncemented stems, the difficulty in identifying the "real" level of the fracture and the actual stability of the stem. As a result, the definition of a standardized treatment is unlikely, thereby high expertise is fundamental for the surgical management of PPFs, so this kind of fractures should be treated only in specialized centres with both high volume of revision joint arthroplasty and trauma surgery.

Interimplant femoral fractures

The number of hip or knee arthroplasties, and internal fixations of the proximal and distal femur, is increasing in proportion to the growing and ageing population, whose life expectancy is lengthening. Thus, fractures of the femur between proximal and distal implants, although rare, are becoming more frequent. Women over the age of 70, with fragile bones and whose ends of the two implants are close to each other ("kissing implants") are particularly vulnerable to them. Reliable and reproducible fracture classifications exist when it comes to 2 prostheses, but they are less well established in the presence of one, or even two, non-prosthetic implants. Their treatment is difficult and must consider the possibility of fracture consolidation while ensuring or restoring the stability and role of the implants. Whether it is the main element of treatment or a complement to prosthesis revision, locked plating forms the basis of the treatment but it must be rigorous, considering that failures are mainly the result of technical errors. Other more invasive treatments (total femoral arthroplasty, cortical sleeves) are offered more rarely if consolidation appears compromised.

Outcomes of operatively treated interprosthetic femoral fractures

AIMS

The prevalence of ipsilateral total hip arthroplasty (THA) and total knee arthroplasty (TKA) is rising in concert with life expectancy, putting more patients at risk for interprosthetic femur fractures (IPFFs). Our study aimed to assess treatment methodologies, implant survivorship, and IPFF clinical outcomes.

METHODS

A total of 76 patients treated for an IPFF from February 1985 to April 2018 were reviewed. Prior to fracture, at the hip/knee sites respectively, 46 femora had primary/primary, 21 had revision/primary, three had primary/revision, and six had revision/revision components. Mean age and BMI were 74 years (33 to 99) and 30 kg/m² (21 to 46), respectively. Mean follow-up after fracture treatment was seven years (2 to 24).

RESULTS

Overall, 59 fractures were classified as Vancouver C (Unified Classification System (UCS) D), 17 were Vancouver B (UCS B). In total, 57 patients (75%) were treated with open reduction and internal fixation (ORIF); three developed nonunion, three developed periprosthetic joint infection, and two developed aseptic loosening. In all, 18 patients (24%) underwent revision arthroplasty including 13 revision THAs, four distal femoral arthroplasties (DFAs), and one revision TKA: of these, one patient developed aseptic loosening and two developed nonunion. Survivorship free from any reoperation was 82% (95% confidence interval (CI) 66.9% to 90.6%) and 77% (95% CI 49.4% to 90.7%) in the ORIF and revision groups at two years, respectively. ORIF patients who went on to union tended to have stemmed knee components and greater mean interprosthetic distance (IPD = 189 mm (SD 73.6) vs 163 mm (SD 36.7); p = 0.546) than nonunited fractures. Patients who went on to nonunion in the revision arthroplasty group had higher medullary diameter: cortical width ratio (2.5 (SD 1.7) vs 1.3 (SD 0.3); p = 0.008) and lower IPD (36 mm (SD 30.6) vs 214 mm (SD 32.1); p < 0.001). At latest follow-up, 95% of patients (n = 72) were ambulatory.

CONCLUSION

Interprosthetic femur fractures are technically and biologically challenging cases. Individualized approaches to internal fixation versus revision arthroplasty led to an 81% (95% CI 68.3% to 88.6%) survivorship free from reoperation at two years with 95% of patients ambulatory. Continued improvements in management are warranted. Cite this article: Bone Joint J 2021;103-B(7 Supple B):122-128.

A pilot agreement study of a new classification system for Peri-implant femoral fractures

BACKGROUND

Peri-implant fractures occur in association with an implant, used to treat a previous injury that is still attached to the bone. We recently published a proposal for a classification system for peri-implant femoral fractures [Videla-Cés, Injury,2019].

AIM

To assess the agreement of our classification system for peri-implant femoral fractures among a group of future users of said classification system.

METHODS

A prospective, multicentre, international agreement pilot study was conducted among a group of independent traumatologists/orthopaedic surgeons (evaluators): senior (a minimum of 10 years' experience) and junior (in fourth or fifth training year). A set of 30 radiographs of peri-implant femoral fractures were selected (stratified into 3 levels of difficulty: low, medium and high). Each evaluator interpreted the radiographs on 2 different occasions separated by a period of one month and in a different order each time. The level of difficulty was masked from the evaluators and they had one week to classify the radiographs each time. Logistic regression and Cohen's kappa coefficient (κ) and its 95% confidence interval (95%CI) were used to assess the accuracy and agreement, both intra- and inter-evaluator. Between senior and junior surgeons was performed an exploratory analysis.

RESULTS

35 traumatologists/orthopaedic surgeons (17 senior and 18 junior) from 16 tertiary hospitals from 4 countries acted as evaluators. The accuracy, percentage of correct classifications (2 digits and 3 letters), in the first and second evaluation was: 56% (95%CI: 53-59%) and 55% (95%CI: 51-57%), respectively. (insert space) Negligible differences were found between junior and senior evaluators (first evaluation, OR: 1.46, 95%CI: 0.82-2.61, p-value: 0.199; second evaluation, OR: 1.06, 95%CI: 0.56-2.00, p-value: 0.860). (insert space) Both medium and low radiograph difficulty were associated with a lower probability of an incorrect classification compared with those of high difficulty (first evaluation, OR: 7.60, 95%CI: 5.24-11.05, p-value: <0.001; OR: 14.15, 95%CI: 9.12-21.96, p-value: <0.001, respectively; second evaluation, OR: 7.11, 95%CI: 4.88-10.38, p-value: <0.001, OR: 15.28, 95%CI: 9.77-23.89, p-value: <0.001). (insert space) The kappa for intra-observer agreement between the first and second evaluation was: 0.66, 95%CI: 0.63, 0.69. The kappa for inter-observer agreement considering all 30 radiographs was: 0.40, 95%CI: 0.40, 0.41 in the first evaluation and 0.39, 95%CI: 0.39, 0.40 in the second evaluation.

CONCLUSION

The proposed classification for peri-implant femoral fractures may be useful and user-friendly. Future studies are needed to assess the how clinically useful this classification system may be (the third phase in the validation process).

Bony callus stiffness indirectly evaluated by the axial load-share ratio in vivo as a guide to removing a monolateral external fixator safely

Purpose

As the monolateral external fixator is increasingly used in trauma-control and definitive management for high-energy long bone fractures, timing the fixator removal remains a challenge for surgeons. The purpose of this study was to determine the feasibility and effectiveness of the bony callus stiffness indirectly evaluated by the axial load-share ratio in vivo as a guide to removing a monolateral external fixator safely.

Methods

A total of 131 patients with tibial shaft fractures treated by the monolateral external fixator in our institution were collected from January 2013 to July 2019. In group I, the fixators were removed based on the clinical and radiological assessment only by the treating surgeon. As for group II, the axial load-share (LS) ratio test was accomplished by another medical team without the knowledge of the clinical results. The external fixator was removed when the mechanical test outcome (LS ratio < 10%) was consistent with the conclusion drawn from the clinical and radiological assessment (bone union achieved) by the treating surgeon.

Results

There was no statistical significance in demographic data between the two groups (P > 0.05). In group I, four patients suffered refracture (the refracture rate was 7.7%) after fixator removal and were successfully treated by an intramedullary nail. In group II, 71 patients underwent fixator removal after the first mechanical test, and another eight patients terminated the external fixation after the second test. None of the 79 patients in group II suffered refracture (the refracture rate was 0%). There was statistical significance in the refracture rate between the two groups (P < 0.05).

Conclusion

The bony callus stiffness indirectly evaluated by the axial load-share ratio in vivo using the additional circular frame components is an effectively quantitative indicator to complement the clinical assessment of fracture healing in a monolateral external fixation treatment. Removal of the monolateral external fixator is safe when the axial load-share ratio dropped below 10%.

Interprosthetic Femoral Fractures Surgical Treatment in Geriatric Patients

Background

Total hip (THA) and total knee arthroplasty (TKA) are becoming an increasingly standard procedure in the whole world. In conjunction with an aging population and increased prevalence of osteoporosis, proper management of periprosthetic, and interprosthetic fractures is of great interest to orthopedic surgeons. This study aims to report the clinical and radiographic outcomes, complications and reoperations of IFFs in geriatric patients.

Methods

A retrospective single-institution case series study was conducted. Between 2011 and 2019, 83 patients underwent surgical treatment for periprosthetic femoral fractures. Thirteen fractures were identified as IFFs. Patient demographics and comorbidities were collected preoperatively, and fractures were classified with the Vancouver and AO unified classification system (AO-UCS).

Results

We included 12 patients (13 hips) with IFFs (AO-UCS type IV.3 B (2/13) type IV.3 C (3/13), type IV.3 D (8/13)). The average patient age was 86.54 (range, 79-89) years. There were 10 females and 2 males. Perioperative morbidity has been identified in 10 of the 12 patients, and the 3-month and 1-year mortality were reported in 2 and 3 patients, respectively. Cerclage cables were used in 9 of 12 patients. One of 12 patients showed a local complication, with no documented implant failure or revision. Patients achieved complete union and returned to their preoperative ambulatory status, and full weight-bearing at an average of 5 (range, 2 to 7) months later.

Conclusion

Management of IFF can be challenging because these fractures require extensive surgical expertise. Locking plate seems to be a valuable treatment option for geriatric patients with IFFs. Despite the complexity of this type of fracture, the overall complication and revision rate, as well as the radiographic outcome are good to excellent.

Level of Evidence

Level III, Therapeutic study.

Results after surgical treatment of periprosthetic proximal femoral fractures. Osteosynthesis with prosthesis preservation vs. prosthesis change

Background: Periprosthetic fractures (PPF) of the femur close to the hip joint have serious consequences for most geriatric affected patients. In principle, apart from the highly uncommon conservative therapy, there are two therapeutic options. On the one hand, the prosthesis-preserving treatment by means of osteosynthesis using plates and/or cerclages in general is available. On the other hand, a (partial) change of the prosthesis with optionally additive osteosynthesis or a proximal femoral replacement can be performed because of prosthesis loosening or non-reconstructable comminuted fractures as well as most cemented stem variations.

The aim of this retrospective study is the analysis of periprosthetic proximal femoral fractures in the presence of a total hip arthroplasty (THA). The outcome of the operated patients is to be investigated depending on the type of care (osteosynthesis with prosthesis preservation vs. prosthesis change).

Material and methods: In a retrospective case analysis, 80 patients with THA and PPF were included. They were divided into two groups. Group I represents the osteosynthetic treatment to preserve the implanted THA (n=42). Group II (n=38) includes those patients who were treated by a change of their endoprosthesis with or without additional osteosynthesis. Specifics of all patients, like gender, age at fracture, interval between fracture and implantation, length of in-patient stay, body mass index, osteoporosis, corticomedullary index and complications such as infections, re-fracture, loosening, material failure or other complications, were recorded and compared. Furthermore, the patients were re-examined by a questionnaire and the score according to Merle d’Aubigné and Postel.

Results: In group I the mean follow-up time was 48.5±23 months (4 years) whereas group II amounted 32.5±24.5 months (2.7 years) (p=0.029). Besides, there were significant differences in age (81± 11 years vs. 76±10 years, p=0.047) and length of in-patient stay (14.5±8.6 days vs. 18.0±16.7 days, p=0.014). According to the score of Merle d’Aubigné and Postel, there were significantly better values for the pain in group II with comparable values for mobility and walking ability.

Conclusion: The treatment of periprosthetic proximal fractures of the femur is dependent on the classification (Vancouver and Johannsen) and in particular on the prosthetic anchoring as well as the extent of the comminution zone. Older patients and patients with osteoporosis are more frequently treated with an endoprosthesis revision. Patients, who have been treated with an osteosynthesis for preserving their endoprosthesis, showed a shorter length of in-patient stay and fewer complications than people with replacement surgery. In contrast to that, patients with prosthesis revision had better outcomes concerning the score of Merle d’Aubigné and Postel.

Periprosthetic femoral re-fractures pathogenesis, classification, and surgical implications

Periprosthetic femoral re-fractures (PFRFs) represent an emerging challenge for orthopaedic surgeons, since their incidence is growing in the last years, but very few experiences about their management have been currently published. The present study aims to (1) introduce, for the first time, an etiologic classification for PRFRs and (2) to provide surgical and pharmacological tips for the correct management of these injuries. Periprosthetic femoral re-fractures (PFRFs) could be classified into traumatic-PFRFs (T-PFRFs) and pathological-PFRFs (P-PFRFs). T-PFRFs, i.e. the "true" periprosthetic re-fractures, present as new fracture lines occurring proximally or distally to a previous periprosthetic fracture, that has correctly healed. They are generally unpredictable injuries but, in selected cases, it is possible to predict them by analyzing the construct used in the treatment of the previous periprosthetic fracture. P-PFRFs, on the other hand, define re-fractures occurring on a previous periprosthetic non-union or delayed union: the new fracture line appears in the same district of the old one. According to the etiologic factors influencing the P-PFRFs pathogenesis, it is possible to define re-fractures caused by mechanical failures, biological failures, septic failures and multifactorial failures, i.e., a combination of the previously mentioned concerns. A successful postoperative outcome, following the surgical management of PFRFs, requires the correct identification of all the underlying causes, which should be promptly and appropriately managed.

[Periprosthetic fractures of the proximal femur]

The incidence of periprosthetic fractures of the proximal femur is increasing due to the growing numbers of hip replacements in old age. The treatment of these fractures is a challenge for the treating physician and standardized procedures are necessary. The unified classification system (UCS) is a suitable tool to establish treatment strategies: On the basis of the fracture localization and extent, bone quality, stability of the prosthesis and the presence of further implants, the fractures can be classified according to the UCS and a treatment algorithm can be derived. This article gives an overview of the diagnostics, classification and characteristics of the various periprosthetic fracture types as well as the treatment.

Interprosthetic femoral fractures: management challenges

Interprosthetic femur fractures are a rare but serious complication following total hip and knee arthroplasty. Classification systems have focused not only on diagnosis but also on treatment algorithm. Critical to the evaluation of patients with these fractures are an assessment of fracture location, bone quality, and the presence of stemmed implants. The gold standard for fracture fixation is locked plating with bicortical and unicortical screws, supplemented with wires or cables as needed. For patients with compromised bone stock or insufficient bony area for fixation, allograft augmentation with struts or interprosthetic sleeves may be used. For fractures with severe bone loss, conversion to a megaprosthesis or total femur replacement may be warranted.

Interprosthetic Femoral Sleeves in Revision Arthroplasty: A 20-Year Experience

BACKGROUND

Interprosthetic femoral fractures in patients with ipsilateral stemmed total hip arthroplasty (THA) and total knee arthroplasty (TKA) can be technically demanding to treat surgically. Nonunion and implant failure are among the main complications following fixation of interprosthetic femoral (IF) fractures. Total femoral arthroplasty (TFA) is associated with a high incidence of infection and instability. IF sleeves have been designed to avoid the disadvantages of these techniques and to provide a stable construct. The aim of this study was to present the results with this device from a single center.

METHODS

We reviewed 26 patients who underwent revision arthroplasty procedures, using custom-made cemented IF sleeves between 1997 and December 2017 in our institution. Two-part sleeves were used in 18 patients and one-part sleeves in 8 patients. The most common indication was an IF fracture (18 patients). Patients were monitored for postoperative complications, implant failure, and re-revision. The minimum follow-up of the survivors with nonrevised sleeves was 12 months.

RESULTS

Twenty-three patients were included for the final analysis. The mean survivorship of the IF sleeve was 4.6 years at latest follow-up (mean 48.5 months; range 12 to 156). The overall rate of complications was 47.8%. The rate of mechanical failure was 21.7%. Late infections occurred in 3 patients (13%). At the latest follow-up, the mean Harris Hip Score was 69.9 points (range 39 to 94), and the mean functional Knee Society Score was 42.5 points (range 0 to 90), with average knee flexion of 95° (range 90° to 100°).

CONCLUSION

The IF sleeve is a valid technique for the management of selected patients with IF fractures, particularly when a stable fracture fixation is not possible. Hip instability is not a concern, and functional improvement is achievable. Careful planning is required preoperatively to avoid mechanical failure.

Outcome of surgical treatment of inter prosthetic fractures: A case series

INTRODUCTION

Interprosthetic fractures occur between a total knee replacement and a femoral stem of either a hemiarthroplasty or total hip replacement. The number of interprosthetic fractures will increase as the number of joint replacements rises. There is currently a paucity of literature looking at the outcomes of interprosthetic fractures. Therefore, we performed a retrospective study to: (1) determine fracture union in patients following surgical treatment of a femoral interprosthetic fracture, (2) measure outcomes included mortality and complications.

HYPOTHESIS

Favoring bone fixation instead of prosthetic revision gives an acceptable rate of reoperation.

MATERIALS AND METHODS

A retrospective case note review of all interprosthetic femoral fractures admitted to a tertiary trauma centre over a 7-year period. There were 24 patients (4 males and 20 females) with a mean age of 82.3 (65-98). The initial operative procedure was a total hip replacement (THR) and a total knee replacement (TKR) in 19 patients, one THR and revision TKR, four hip hemiarthroplasty and TKR. There were 23 cemented femoral stems, and 1 uncemented femoral stem. The median time to surgery was 84hours. The median length of hospital stay was 16 days. Nineteen patients underwent open reduction internal fixation and 1 of these used a strut graft. Two patients underwent revision knee replacements and 3 underwent a revision hip replacement. All patients had at least 2 years clinical follow-up.

RESULTS

One patient died within 30 days of fracture, leaving 23 patients to assess bone union. Another patient died within 1 year of fracture. Three out of 24 patients (12.5%) suffered a complication that required further surgery. The fracture united in 19/23 (82.6%) of patients and the 2-year mortality rate was 5/24 (20.8%).

DISCUSSION

Interprosthetic fractures are complex fractures occurring in elderly patients with multiple medical comorbidities. Whenever possible bone fixation instead of prostehtic revision give a low rate of complication and reoperation. The surgical treatments are complex, but with a well-performed surgical technique and an adequate rehabilitation program can result in satisfactory outcomes.

LEVEL OF EVIDENCE

IV, retrospective case series.

Interprosthetic femoral fractures: Morbidity and mortality in a retrospective, multicenter study

INTRODUCTION

Interprosthetic femoral fractures (IFF) are becoming more frequent; however they have not been the subject of many publications and the largest study on this topic includes only 30 cases. The complication rate and clinical outcomes have only been evaluated in small case series. This led us to conduct a retrospective, multicenter, observational study in IFF patients with at least 12 months' follow-up to (1) determine the mortality and morbidity (2) determine the clinical and radiological outcomes and (3) identify elements of the treatment indications.

HYPOTHESIS

The morbidity and mortality rates will be comparable to those in recent studies on this topic.

MATERIALS AND METHODS

The study included 51 patients (49 women, 2 men) with a mean age of 82.8±9.2 years [55-97], a mean Parker score of 4.9±2.4 and a mean Katz score of 4.4±1.4 who had suffered an IFF between 2009 and 2015. According to the SoFCOT modifications of the Vancouver classification, 30 fractures were interprosthetic in the shaft segment where there were no implants (19 double C and 11 type D (corresponding to a type C with less than two diaphysis widths between the extension stems of the hip and knee implants)) while 21 were periprosthetic, with 12 around the THA (11 B1 and 1 B3) and 9 around the TKA (8 B1 and 1 B3). One patient was treated conservatively with an external fixator but died the next day, 2 patients received a new total hip arthroplasty and 47 underwent plate fixation of their fracture (one patient was treated non-operatively because of poor medical condition).

RESULTS

One patient was lost to follow-up, and nine died during the first 6 months. Six early surgical site complications occurred and 13 general ones. Within 1 year of the IFF, there were six mechanical complications, two surgical site infections and two cases of loosening. The mean follow-up was 27.6±17.2 months. The mean time to union was 19.25±8.8 weeks. The mean final Parker score was 3.37±2.6 and the mean Katz score was 2.98±1.8; both were significantly lower than the initial scores. Six patients died between months 12 and 50. The overall mortality at the final review was 31% (16/51) with a median survival of 3.45 years.

DISCUSSION

Our hypothesis was not confirmed because the mortality and morbidity in our study were higher than in other published studies. In the six relevant studies identified, the surgical site infection rate was 12.3%, the major revision rate was 11.6% and the mortality rate was 6.5%. In our study, these values were 24%, 24% and 31%, respectively. These worse results may be explained by the very fragile nature of the studied population and the surgeons not following appropriate technical rules for fracture fixation.

LEVEL OF EVIDENCE

IV, Retrospective study.

Proposal for the classification of peri-implant femoral fractures: Retrospective cohort study

Background Peri-implant fractures occur in association with an implant used to treat a previous injury and that is still attached to the bone. Peri-implant fractures are considered to be relatively "new" fractures and they lack any classification system that is accepted in practice. Generally, the fracture classification systems currently used in our clinical practice were not developed or validated using rigorous scientific evaluation methods. Aim To provide data for a proposed classification of peri-implant femoral fractures. Methods This is an international and multicentre study (12 centres) based on a cohort of consecutive peri-implant fractures with the criterion being: a fracture in any segment of the femur in association with previously-used osteosynthesis material, whether a nail, plate or screws. A proposed system for the classification was tested, based on a topographical classification using alphanumeric coding, following a similar nomenclature to that explained in the "Vancouver-Classification-for-Total-Hip-Arthroplasty-Periprosthetic-Fractures", and classified according to whether the implant is a nail, a screw or a plate, and the location of the fracture in relation to the original implant and the affected femoral segment. The study coordinator performed the first classification exercise, which was discussed subsequently for the study coordinator group to reach a consensus. A descriptive analysis of the fractures was produced. The proportion of peri-implant femoral fractures was estimated, and 95% confidence interval (95%CI) was calculated. Results Between January 2013 and December 2016, data on a total of 143 peri-implant femoral fractures were collected. Only 5 (3.5%) fractures had to be discussed to reach a consensus. The most common peri-implant femoral fractures were located at the diaphyseal segment (#32) and associated with nails or plates: 51%, 73/143, 95%CI:43-59%; at the proximal segment (#31): 39%, 56/143, 95%CI:32-47%; and at the distal femoral segment (#33): 10%, 14/143, 95%CI:6-16%. The highest proportion of peri-implant femoral fractures corresponded to #31-AN (trochanteric and neck area) and #32-CNP (diaphysis fractures distant from the implant, often distal and spiral). Conclusion The proposed classification for peri-implant femoral fractures appears to be useful and easy to accomplish. Future studies will be necessary to validate it and demonstrate the effectiveness of its application in clinical practice.

Interimplant femoral fractures: risk factors, treatment and evolution

OBJECTIVE

The aim of this study is to determine the risk factors involved in the development of these fractures and analyze the treatments used as well as their influence on the clinical and functional prognosis of patients.

MATERIALS AND METHODS

We made an observational, retrospective case-control study, with a sample of 38 patients (40 femoral bones) operated in our hospital, who had two femoral ipsilateral implants, proximal and distal. We found 10 cases of interimplant fracture and 28 patients who had not suffered a fracture (2 of them had bilateral implants). We analyzed the influence of different variables, such as age, gender, comorbidities, radiological variables, type of treatments employed, clinical evolution, etc. RESULTS: the female sex was predominant in both groups, 80.7 was the average age. Osteoporosis was statistically significant (P=.007) for the development of these fractures. We did not find statistical significance in the radiological variables. Surgical treatment was the most frequent, and the plate of osteosynthesis the most employed option. We found a death rate of 40% at 4 years. Although all fractures healed, the survivors' ambulation ability was reduced.

CONCLUSIONS

interimplant fractures are predominant in elderly women. Osteoporosis is a statistically significant risk factor. Despite optimal treatment and fracture healing, functional outcomes were decreased. Specific classification systems and therapeutic algorithms are necessary to improve the management and prognosis of these patients.

Interprosthetic Fractures of the Femur

As the rate of hip and knee arthroplasty procedures increases, so will the rate of interprosthetic fractures. Several factors, including bone quality, bone quantity, and stability of the prosthetic components, play a role in determining the appropriate operative treatment. Patients with stable components should undergo reduction and internal fixation, while patients with loose components should undergo either revision arthroplasty, with or without additional fixation, or conversion to total femur replacement. Despite implant and technique advances, complications remain frequent. [Orthopedics. 2018; 41(1):e1-e7.].

A new classification of TKA periprosthetic femur fractures considering the implant type

Background

The treatment aims of periprosthetic fractures (PPF) of the distal femur are a gentle stabilization, an early load-bearing capacity and a rapid postoperative mobilization of the affected patients. For the therapy planning of PPF a standardized classification is necessary which leads to a clear and safe therapy recommendation. Despite different established classifications, there is none that includes the types of prosthesis used in the assessment. For this purpose, the objective of this work is to create a new more extensive fracture and implant-related classification of periprosthetic fractures of the distal femur based on available classifications which allows distinct therapeutic recommendations.

Methods

In a retrospective analysis all patients who were treated in the University Hospital Leipzig from 2010 to 2016 due to a distal femur fracture with total knee arthroplasty (TKA) were established. To create an implant-associated classification the cases were discussed in a panel of experienced orthopaedists and well-practiced traumatologists with a great knowledge in the field of endoprosthetics and fracture care. In this context, two experienced surgeons classified 55 consecutive fractures according to Su et al., Lewis and Rorabeck and by the new created classification. In this regard, the interobserver reliability was determined for two independent raters in terms of Cohen Kappa.

Results

On the basis of the most widely recognized classifications of Su et al. as well as Lewis and Rorabeck, we established an implant-dependent classification for PPF of the distal femur. In accordance with the two stated classifications four fracture types were created and defined. Moreover, the four most frequent prosthesis types were integrated. Finally, a new classification with 16 subtypes was generated based on four types of fracture and four types of prosthesis. Considering all cases the presented implant-associated classification (κ = 0.74) showed a considerably higher interobserver reliability compared to the other classifications of Su et al. (κ = 0.39) as well as Lewis and Rorabeck (κ = 0.31). Excluding the cases which were only assessable by the new classification, it still shows a higher interobserver reliability (κ = 0.70) than the other ones (κ = 0.63 or κ = 0.45).

Conclusions

The new classification system for PPF of the distal femur following TKA considers fracture location and implant type. It is easy to use, shows agood interobserver reliability and allows conclusions to be drawn on treatment recommendations. Moreover, further studies on the evaluation of the classification are necessary and planned.

Periprosthetic fractures: epidemiology and current treatment

Periprosthetic fractures are becoming increasingly frequent due to aging population and growing number of total joint replacements involving joints different from hip and knee, such as shoulder and elbow. The treatment of these fractures still represents one of the major challenges for the orthopedic surgeon. Despite all efforts to understand and treat these patients, high rate of failure and mortality are still reported. In this review, the epidemiology of periprosthetic fractures, risk factors and results of surgical treatment are disclosed. Moreover, we propose a treatment algorithm based on the findings of the New Unified Classification System.

Management of Interprosthetic Femur Fractures

Femoral fractures between a total hip arthroplasty prosthesis and total knee arthroplasty prosthesis, also called interprosthetic fractures, are challenging clinical problems. The number of patients who have undergone ipsilateral primary or revision joint arthroplasty procedures in both the hip and the knee continues to rise, and the number of interprosthetic fractures is increasing, as well. The growing body of biomechanical and clinical literature on interprosthetic fractures reflects the increased frequency of and interest in these injuries. Similar to the management of periprosthetic fractures, the management of interprosthetic fractures depends on the location of the fracture, the stability of the implant, and the ability to achieve stable fracture fixation. These factors are the basis of recently described classification systems and treatment strategies. In patients with stable implants, fracture fixation alone is performed. When the implant is loose, both revision arthroplasty and fracture fixation may be required to provide stability of the limb.

Interprosthetic femoral fractures: Treatment with a lateral angular-stable plate

OBJECTIVE

To study the causes and outcomes of patients with interprosthetic femoral fractures.

MATERIAL AND METHODS

A retrospective review conducted on 7 patients treated between 2010 and 2013. The knee arthroplasties had been implanted for at least 5 years, and those of the hip less than a year. They were bipolar cemented in 6 patients and totally non-cemented in one patient, all of them implanted due to a displaced femoral neck fracture. They were treated using osteosynthesis with angular stability plate covering the whole interprosthetic femoral segment. Except for one patient, all have been reviewed at least 12 months.

RESULTS

The patients included 6 women and one man, with a mean age of 84.7. The fracture, always by low energy, occurred between 2 and 8 months after that of the hip without the implants being mobilized. Four of them were located at diaphyseal level, and 3 at supracondylar level, and unrelated to the type of knee implant. There was consolidation in all patients at a mean of 4.5 months, without a re-operation in any of them, and with no mortality during the follow-up period. All patients walked independently at the time of the fracture, and all of them have managed to return to walking independently, having lost as average 20° of knee flexion in cases of supracondylar fracture.

CONCLUSIONS

The most important factors in our patients regarding the producing of the fracture have been the changes in the ability to walk after knee replacement and bone fragility. Angular stability plates give good results in the treatment of interprosthetic femoral fractures.

Periprosthetic fractures associated with total knee arthroplasty

Fractures around total knee arthroplasties pose a significant surgical challenge. Most can be managed with osteosynthesis and salvage of the replacement. The techniques of fixation of these fractures and revision surgery have evolved and so has the assessment of outcome. This specialty update summarises the current evidence for the classification, methods of fixation, revision surgery and outcomes of the management of periprosthetic fractures associated with total knee arthroplasty.

Cite this article: Bone Joint J 2016;98-B:1489–96.

Clinical outcome of interprosthetic femoral fractures treated with polyaxial locking plates

INTRODUCTION

Total hip arthroplasty (THA) and total knee arthroplasty (TKA) are common procedures in the increasing older population. According to the AAOS, approximately 19,200 Americans are actually living with ipsilateral prosthetic hip and knee leading to 240 interprosthetic fractures annually. Few reviews and case reports give an idea of the obvious problem to achieve consolidation in interprosthetic fractures. Preconfigured plates have been shown to be superior compared with other treatments in patients with stable components. Utilization of internal fixators for interprosthetic fractures might be advantageous. The purpose of this study was to evaluate interprosthetic femoral fractures with polyaxial locking plate treatment in regard to surgical procedure, complications, and clinical outcome.

METHODS

Between 2005 and 2012, 143 patients underwent surgical treatment for periprosthetic femur fractures. Thirty-two fractures were identified as interprosthetic fractures. Five patients were excluded. Fractures were classified according to OTA/AO system, Vancouver, Rorabeck, Soenen and Pires. Trauma fellowship trained orthopaedic surgeons performed the surgeries using a NCB-construct (Zimmer Inc., Warshaw, IN). Plate choice was determined according to radiographic classification. Submuscular plate insertion was performed if possible. Complications were recorded concerning infection, union, fixation failure, and revision surgery.

RESULTS

Twenty-seven patients were identified. There were 92.6% females. Follow-up by regular outpatient clinic visits was 24 months. Surface replacements were found in 18 TKA. Nine patients had a stemmed femur component of their TKA. 89% healed after the index procedure. Three patients developed a nonunion with 1 construct leading to hardware failure. Previous revision THA or Pires/modified Vancouver classification did not influence nonunion formation, but all patients with nonunion formation were classified as AO/OTA type B (p=0.001). These fractures were treated with longer plates (p=0.015), but with similar working length (p=0.400). Plate design, additional cerclages, or submuscular insertion did not influence nonunion formation.

CONCLUSION

Interprosthetic fracture treatment remains challenging. NCB-locked plating can achieve satisfactory results. Additional soft tissue damage can be prevented by submuscular plate insertion. Treatment of type B fractures resulted in significantly greater nonunion rate. Therefore, consideration of the individual fracture type is essential to determine plate length, plate type, and additional bone grafting or BMP supplementation.

What is new in distal femur periprosthetic fracture fixation?

Distal femoral periprosthetic fractures are on the rise. Increased mortality of these injuries is also evident from recent data. Their incidence and risk factors have been extensively reported in the past but new data are being available that merit attention. The increased incidence and the even higher projected incidence should direct the focus of future strategies to the education of surgeons, relevant capacity of hospital and reconfiguration of health care resources. New and potentially modifiable risk factors should be taken into consideration to the informed consent process and new studies should be developed to clarify the causative relationship of the new risk factors such as the peptic ulcer disease and the COPD. The main internal fixation techniques remain the lateral locking plating and the retrograde intramedullary nailing. New techniques in plating are the supplementary medial plate in selected cases and the far cortical locking. Nailing is considered a valid option especially in fractures located well above the anterior flange of the femoral component of the arthroplasty. Results and outcomes from good quality studies are still sparse regarding the comparison between plating and nailing. Interprosthetic fractures constitute an entity that is lately gaining considerable attention. The best method of management of these injuries is still evolving with considerable amount of work being done in the clinical and biomechanical level.

The outcome of Polyax Locked Plating System for fixation distal femoral non-implant related and periprosthetic fractures

The objective of this study was to report on the safety, efficacy and clinical outcomes of the Polyax Locked Plating System (Biomet, Warsaw, IN, USA) in the management of acute (non-implant related and periprosthetic) distal femoral fractures. We retrospectively reviewed 71 patients with 73 distal femoral fractures. Thirty-three of the included fractures occurred around previously placed implants. The average patients' age was 67 years (range 18-98). There were 7 early postoperative complications (9.5%) including one deep surgical site infection, 2 pulmonary embolisms and 4 urinary or respiratory infections. At final follow-up (mean 12, range 9-55 months) all fractures progressed to clinical and radiological union. However, major revision surgery for healing problems was required in 5 cases (6.8%) and minor in 3 cases (4.1%). The average time to healing was 6 (range 3-23) months. Angulation less than 5 degrees in any plane was observed in 66 cases (89.7%), within 5-10 degrees in 5 cases (7.3%) and within 10-15 degrees in 2 cases (2.9%). The mean pre-injury and final follow-up values of Glasgow Outcome Scale were 1.5(1-3) and 1.7(1-3) respectively. Overall 61 patients (83.53%) retained their pre-injury activity status. The Polyax Locked Plating System offers a safe and efficient fixation in distal femoral fractures.

Incidence of and risk factors for femoral fractures in the gap between hip and knee implants

PURPOSE

The purpose of this study was to analyse the incidence of interprosthetic femoral fractures and describe risk factors for them.

METHODS

Between 2009 and 2015, we selected patients who were carrying two implants (hip and knee) in the same femur. We collected demographic and clinical data and performed a radiological evaluation to analyse the gap between implants-the femoral canal area and total femoral area-in the axial plane. We defined interprosthetic fracture as that corresponding to a Vancouver type C fracture and types 1 and 2 according to the Su classification.

RESULTS

We studied 68 patients who had total knee arthroplasty (TKA), and 44 patients who had total hip arthroplasty (THA); 24 patients an intramedullary nail. We found six interprosthetic fractures (8.8 %), all in patients with a non-cemented THA. There was a tendency towards statistical difference (p = 0.08). Patients with an additional implant at the proximal femur were statistically less likely to have an interprosthetic fracture (p = 0.04). In radiological results, we found more interprosthetic fractures in patients who had an increased femoral canal area in the axial plane just distal to the tip of the hip implant.

CONCLUSIONS

Identifying risk factors for this specific type of fracture may facilitate their prevention. Better implant stability and the presence of a gap between stems in a lower canal zone appear to hinder the occurrence of interprosthetic fractures.

Periprosthetic femoral fractures--incidence, classification problems and the proposal of a modified classification scheme

INTRODUCTION

The increasing incidence of periprosthetic fractures correlates directly with the year-after-year increasing frequency of primary joint replacement surgery. The most common fracture localisation is the femur. The undisputed leader in frequency is the fracture that occurs around a total hip arthroplasty. Unfortunately, no general epidemiologic data exist dealing with exact fracture incidence numbers. Furthermore, existing classifications are lacking important information like time point of fracture occurrence, type of the implanted prosthesis and implantation technique (cemented vs. cementless). Additionally, information about mechanical quality of the bone structure and the fracture type are also missing in part.

METHODS

We scanned the literature for adequate and widely used classifications in the field of hip and knee arthroplasty. In a next step we analyzed those classification systems in order to find out to what extent they are able to describe the specific aspects of the fracture event. Therefore we compared the existing classifications and presented their most relevant emphasis. Furthermore, we looked at our own patient population to evaluate incidence of fracture occurrence over time and percentage of loosened components.

RESULTS

The existing classification systems address themselves specifically to the task of describing fracture localization and to some extent fracture type, or combine these two in order to calculate the possibility of loosening of the implanted prosthesis. Some of the important criteria like mechanical quality of the bone stock, primary implantation technique or time point of the prosthesis loosening (prior to or because of the fracture) remain ignored. The incidence of periprosthetic femur fractures at our department increased approximately 2.5 fold over the past two decades. The risk of suffering from a periprosthetic fracture was substantially higher after THA than after TKA. We observed a loose femoral component of the THA in about 45 % of the cases. Finally, we postulate the application of a modified classification for periprosthetic fractures as an alternative to the already published ones; not only for the femur, but also universally for all joints with an arthroplasty.

CONCLUSION

The classification that is introduced in this study allows, in our opinion, a differentiated reflection of the given post-traumatic pathologic changes and enables the description of the fracture itself according to a generally accepted fracture classification scheme.

Interposition sleeve as treatment option for interprosthetic fractures of the femur: a biomechanical in vitro assessment

PURPOSE

The number of patients having hip and knee arthroplasties on the ipsilateral leg is going to rise. In this regard, the prevalence of interprosthetic femoral fractures is going to increase further. The treatment of these fractures is difficult and sometimes it is impossible to perform an osteosynthesis because of worse bone quality. The goal of this study was to investigate the use of an interposition sleeve as an alternative treatment option for interprosthetic fractures with major bone loss.

METHODS

Six human cadaveric femurs were instrumented using cemented hip- and knee prosthesis. Interprosthetic fractures were induced during a four-point-bending test and then treated using the interposition sleeve. Afterwards the constructs were tested using the four-point-bending test again.

RESULTS

Load-to-failure of the construct before fracturing was significantly higher than after treatment with the interposition sleeve (10681 N vs. 5083 N; p = 0.002). The failure mechanism of the femurs with the interposition sleeve was plastic deformation of the hip or knee prosthesis. The interposition sleeve did not fail in any specimen.

CONCLUSION

The interposition sleeve is a valuable treatment option for interprosthetic fractures in situations in which osteosynthesis is impossible or insecure due to major bone defects. However, fracture healing should be preferred whenever possible.

Interprosthetic femoral fractures treated with locking plate

PURPOSE

Interprosthetic fractures are challenging to manage. Although treatment of femoral fractures around a single implant has been described, there is little literature for treatment of interprosthetic femoral fractures. This study analyses the management and outcomes of 15 patients with interprosthetic femoral fractures treated with locking plates.

METHODS

A retrospective chart review was conducted of 17 patients with interprosthetic femur fracture treated with locking plates from 2002 to 2013. Patient demographics and comorbidities were collected. Preoperatively, patients were classified with the Vancouver or Su classification system. Intraoperative use of bone graft and/or cerclage cables was also examined. Clinical and radiographic outcomes were evaluated for union, time to full weight bearing, return to preinjury level of activity, and pain assessed with visual analog scale (VAS).

RESULTS

There were 15 patients with interprosthetic fractures meeting criteria for this study. Average patient age was 80.53 (range, 61-92) years. Bone grafting was used in 23.5% (four of 17) and cerclage cables in 29.4% (five of 17). Patients achieved complete union and return to full weight bearing an average of 4.02 (range, two to six) months later. Average VAS pain score was 1.00 (range, zero to six). All patients returned to their preoperative ambulatory status.

CONCLUSION

Locking plates could achieve satisfactory results for interprosthetic fractures. Considering an individual's fracture type, bone quality and protheses to determine the appropriate plate length and optional use of cerclage and/or bone graft was essential. In this limited sample size, interprosthetic fractures occurred at similar rates at the supracondylar region and diaphysis.