[Periprosthetic fractures after total hip arthroplasty : classification, diagnosis and therapy strategies]

[Periprosthetic fractures-Diagnostics, classification and treatment]

BACKGROUND

Due to the increase in hip and knee prosthetic as a result of the demographic changes, with raised levels of activity among older persons with geriatric comorbidities, a continuous increase in periprosthetic fractures can be observed.

OBJECTIVE

The incidence and causes of periprosthetic fractures, presentation of diagnostic pathways and derivation of a recommendation according to generally accepted classifications.

MATERIAL AND METHOD

Literature search of basic scientific work, recommendations of experts as well as evaluation of own patient collective.

CONCLUSION

With a growing number of prosthetic interventions in combination with increasing patient age, an increase in periprosthetic fractures is to be expected. The treatment of periprosthetic fractures is complex and requires detailed analysis of the location of the fracture and its morphology as well as the recognition of possibly loosened prosthetic material. Based on this information, the correct surgical treatment can be determined and scheduled in an appropriate center of care. In geriatric patients with corresponding comorbidities, an individual holistic treatment plan should be developed.

[Periprosthetic acetabular fractures and defects : Trauma meets ortho]

BACKGROUND

Periprosthetic acetabular fractures are considered to be a severe and challenging complication in total hip arthroplasty. To date, there are no internationally applicable standardized recommendations which can assist orthopedic surgeons and trauma surgeons in the treatment of patients.

OBJECTIVE

The aim of this article is to report on the current state of knowledge on periprosthetic acetabular fractures, to present the commonly used classification systems and to demonstrate appropriate treatment algorithms together with personal experiences.

MATERIAL AND METHODS

A selective search of the existing literature was carried out and the commonly used classification systems and treatment options for periprosthetic acetabular fractures were compiled and are discussed in relation to the in-house cases.

RESULTS

The comparison of the classification systems showed that frequently only fractures which have a purely traumatic origin are included among periprosthetic acetabular fractures. Insufficiency fractures within the framework of acetabular defects, which also belong to the group of acetabular fractures, are frequently included in revision arthroplasty. The management of defects with appropriate implants represents a challenge. By the combination of osteosynthesis and implant replacement, the selection of implants can often be de-escalated.

CONCLUSION

Periprosthetic acetabular fractures represent a complex operation for both trauma surgeons and for specially trained orthopedic surgeons, which necessitate a high level of expertise. By the cooperation between trauma surgeons and orthopedic surgeons good treatment results can be achieved and recommendations for the selection of implants can be made.

[Techniques and results of primary hip arthroplasty in geriatric acetabular fractures]

As a result of demographic changes, there is an increase in geriatric acetabular fractures [1, 2]. Geriatric patients often have comorbidities, such as pre-existing coxarthritis, reduced bone quality or limited compliance, which makes injury-adapted follow-up treatment difficult [3]. As a result joint-preserving interventions often fail at an early stage, so that hip arthroplasty is necessary in the short term. The 1‑year mortality after surgically stabilized acetabular fractures is 8.1%, a significant increase by a factor of 4 compared to the age group [4]. This illustrates that differentiated criteria for the indication of joint-preserving surgery versus arthroplasty are necessary to avoid reoperations and complications. Criteria for the indications for primary arthroplasty are fracture type, pre-existing coxarthritis, poor bone quality, limited compliance and patient age (> 75 years) [5, 6].In the following article, three treatment strategies for geriatric acetabular fractures and periprosthetic acetabular fractures are presented; the 1‑stage prosthesis implantation without osteosynthesis, the 1‑stage prosthesis implantation with osteosynthesis and the 2‑stage approach with limited osteosynthesis and early total arthroplasty. The advantages and disadvantages of these options are presented based on cases and the various aspects of the treatment. The treatment of geriatric acetabular fractures is an operative challenge for the surgeon and requires a high level of expertise in both special trauma surgery and revision arthroplasty and thus represents a special interface in the fields of orthopedics and trauma surgery.

[Postoperative imaging of the hip]

CLINICAL ISSUE

To assess postoperative imaging of the hip joint regarding possible complications, it is indispensable to have in-depth knowledge of commonly used surgical techniques, access routes, and the implanted materials.

STANDARD RADIOLOGICAL METHODS

While radiography is used to evaluate the position of foreign material and to rule out periprosthetic fractures that have occurred intraoperatively, follow-up examinations might show signs of material failure, aseptic loosening, prosthesis infections, or the occurrence of heterotopic ossifications. If radiographic findings are ambiguous, computed tomography (CT) may be used to clarify findings, whereas magnetic resonance imaging (MRI) is helpful to identify intra- and periarticular soft tissue pathologies such as surgery-associated cartilage and ligament damage, muscle insufficiency, or metallosis.

METHODOLOGICAL INNOVATION AND EVALUATION

To guide clinical decision making in common postoperative complications, various classification systems are available, e.g., for periprosthetic fractures, aseptic loosening, or heterotopic ossification. However, the differentiation between aseptic material loosening and septic endoprosthesis infection remains challenging if based on imaging alone.

PRACTICAL RECOMMENDATIONS

The assessment of postoperative hip imaging should be closely linked to the respective surgical technique and the implanted foreign material, whereby different probabilities of specific complications can be derived.

Periprosthetic occult acetabular fracture: an unknown side effect of press-fit techniques in primary cementless total hip arthroplasty

BACKGROUND

This study sought to investigate the prevalence and risk factors of periprosthetic occult acetabular fracture occurring during cementless acetabular cup insertion in patients undergoing primary total hip arthroplasty (THA) and to assess the clinical consequences of these fractures.

METHODS

A total of 232 hips (n = 205 patients) were included in this study. A periprosthetic occult acetabular fracture was defined as that which was unrecognised intraoperatively and was undetectable on post-operative radiographs yet was successfully diagnosed on post-operative computed tomography (CT) images. Clinical (age, sex, body mass index, and preoperative diagnosis) and surgical (additional screw fixation, cup rim size, and cup type) variables were analysed to identify risk factors for periprosthetic occult acetabular fracture.

RESULTS

Sixteen (6.9%) periprosthetic occult intraoperative acetabular fractures were identified. In addition, one (0.4%) periprosthetic acetabular fracture was found during operation. The superolateral wall (9/16 hips; 56.3%) was the most frequent location. In addition, one (0.4%) periprosthetic acetabular fracture was found during operation. Male sex was the only factor associated with an increased risk for periprosthetic occult intraoperative acetabular fracture (odds ratio for male versus female sex: 4.28; p = 0.04). There was no significant association between cup type and the occurrence of periprosthetic occult acetabular fracture. All 16 hips with periprosthetic occult intraoperative acetabular fracture were healed at the final follow-up visit without the requirement for any additional surgical interventions.

CONCLUSION

The results of the current study suggest that periprosthetic occult acetabular fractures are common during press-fit acetabular cup insertion in primary THA. Surgeons should have a high index of suspicion and early CT imaging referral in male patients who present with unexplained early post-operative groin pain in primary THA using cementless acetabular cups.

[Periprosthetic fractures of the acetabulum: osteosynthesis]

In most cases periprosthetic fractures of the acetabulum are complex injuries and are extremely challenging for the treating medical team. Over the years the frequency of this overall rare entity has increased due to demographic changes. In recent years several treatment algorithms were published and provided the possibility of developing standardized treatment concepts. The classification of the fractures and a dedicated preoperative strategy are highly important for the quality of patient-centered care. In the literature the frequency of intraoperative fractures was initially given as 0.4%; however, several studies have been published in which a far higher rate of intraoperative fractures was detected by computed tomography (CT), often referred to as so-called occult fractures. The causes are multifactorial and there is significant association with whether cement-free press-fit acetabular cups were used or cemented forms. In approximately 75% of the cases a low energy impact was the cause of the fracture. In these patients systemic processes, such as osteoporotic alterations of the bony substance or the possible presence of low-grade infections should be considered. This article gives an overview of the diagnostics, planning, challenges and osteosynthetic treatment options for periprosthetic fractures of the acetabulum.

[Periprosthetic fractures following total hip and knee arthroplasty: Risk factors, epidemiological aspects, diagnostics and classification systems]

Periprosthetic fractures following hip and knee arthroplasty are potentially severe complications. As a fundament in diagnostic and therapeutic procedures, specific classification systems are necessary to ensure an optimal individualized treatment of these sometimes complicated fractures. This review article summarizes the epidemiological aspects, risk factors and diagnostics of periprosthetic hip and knee fractures. The most frequently used location related fracture classifications systems are explained. In addition, the recently introduced unified classification system (UCS), which is applicable to any location of periprosthetic fractures, is described in detail. Initial studies have shown a reliable applicability of the UCS to periprosthetic hip and knee fractures.

Incidence and predisposing factors of periprosthetic proximal femoral fractures: a literature review

PURPOSE

The purpose of this review article was to investigate the incidence and predisposing factors for periprosthetic proximal femoral fractures (PFF) following total hip arthroplasty.

METHODS

We performed a comprehensive search of the medical literature in MEDLINE and EMBASE databases to review articles related to PFF, their incidence and risk factors.

RESULTS AND CONCLUSIONS

The incidence of PPF after primary THA was, in general, lower than after revision THA both for intra- and postoperative PFF. The rate of intraoperative PFF ranged from 0.1% to 27.8% and of postoperative PFF from 0.07% to 18%. Predisposing factors for intraoperative PFF are osteoporosis, rheumatoid arthritis, femoral preparation and surgical technique used to insert the rasp or femoral component, the use of press-fit cementless stems, and revision THA. In case of postoperative PFF, the following seem to be significant risk factors: advanced age, female gender, post-traumatic osteoarthritis, osteoporosis and rheumatoid arthritis, proximal femoral deformities, previous surgery of the affected hip, implant type (especially cementless stems and press-fit implantation), technical errors such as cortical perforation, cortical stress risers, low-energy trauma, osteolysis, loosening and revision THA.

Impaction bone grafting for the reconstruction of large bone defects in revision knee arthroplasty

OBJECTIVE

Regeneration of autologous bone stock and formation of a stable implant bed by impaction of morselized bone allograft.

INDICATIONS

Bone loss after septic and aseptic loosening or tumour resection.

CONTRAINDICATIONS

Persistent infection, one-stage septic revision, poor therapeutic compliance, extensive uncontained metaphyseal defects with cortical thinning of the diaphysis.

SURGICAL TECHNIQUE

Whilst the surgeon removes the loose prosthesis, the assistant prepares the graft. The medullary canal is sealed with a cement restrictor. Graft particles of different sizes are densely impacted around a trial stem. The highest level of stability is achieved by using large particles interspersed with small filler particles. Low-viscosity cement facilitates cement penetration and ensures strong interdigitation with the impacted graft mass after implantation of the prosthesis. Uncontained metaphyseal defects are treated with prosthetic augments.

POSTOPERATIVE MANAGEMENT

Gait training, physiotherapy with isometric quadriceps exercises, partial weight-bearing for 6 weeks, resistance training begins 8 weeks postoperatively.

RESULTS

Between 2010 and 2012, 28 patients with large bone defects [Anderson Orthopaedic Research Institute (AORI) grade: 21 × F3, 3 × F2, 13 × T3, 8 × T2] underwent total knee revision with impaction bone grafting. The mean follow-up was 27.7 months (range 21-47 months). On average, patients had undergone 2.5 previous revisions. Implant survival was 82.0 % (95 % CI = 62.5 %-92.1 %) for any reason of revision as the endpoint and 93.1 % (95 % CI = 74.5-98.4 %) for aseptic revision as the endpoint. The mean postoperative Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score was 35.4 (range 3.3-101.6, SD ± 26.2). The mean KSS was 70.6 (range 20-100, SD ± 26.8).

Postoperative periprosthetic fractures in patients with an Exeter stem due to a femoral neck fracture: cumulative incidence and surgical outcome

PURPOSE

The purpose of this study is to report on the cumulative incidence and the outcome of surgically-treated postoperative PPFs in patients with femoral neck fractures treated with a THA or HA using an Exeter stem.

METHODS

A consecutive series of patients operated during 1998-2010 due to a non-pathological femoral neck fracture using an Exeter stem were included in this cohort study. Patients were followed until 2012, or death, in order to obtain information about reoperations due to postoperative PPFs, and subsequent re-operations after surgery due to PPFs. In addition to local audit data the Swedish National Board of Health and Welfare's registry was used to identify patients who had been re-operated upon elsewhere in Sweden.

RESULTS

A total of 2,757 patients (median age 82 years, 2,019 females) were identified and included in the study. Of these patients, 63 (2.3%) sustained a postoperative PPF that was treated surgically. The majority of the Vancouver B1 (n = 21/23) and C (n = 14/14) fractures were treated using open reduction and internal fixation (ORIF), whereas most of the B2 (n = 16/25) fractures and the only B3 fracture were treated with stem revision. Three (4.8%) patients were subsequently re-operated upon due to fracture-related complications, all B2 fractures, and were treated with ORIF (n = 2) or stem revision (n = 1).

CONCLUSION

The cumulative incidence of surgically treated PPFs was considerable among patients with Exeter stems operated due to a femoral neck fracture. The re-operation rate due to fracture-related complications was highest among patients with B2 fractures.

Mono- versus polyaxial locking plates in distal femur fractures: a prospective randomized multicentre clinical trial

PURPOSE

Treatment of complex fractures of the distal femur utilizing monoaxial locking plates (e.g. Less Invasive Stabilisation System, LISS®, Synthes) is considered to be superior to conventional plating systems. Due to the limitation that the thread forces the screw into pre-determined positions, modifications have been made to allow screw positioning within a range of 30° (Non Contact Bridging, NCB®-DF, Zimmer). For the first time, this multicenter prospective randomized clinical trial (RCT) investigates the outcome of LISS® vs. NCB®-DF treatment following complex fractures of the distal femur.

METHODS

Since June 2008, 27 patients with a fracture of the distal femur (AO ASIF 33-A-C and periprosthetic fractures) were enrolled in this study by four university trauma centres in southern Germany. Clinical (e.g. range of motion, Oxford knee score, Tegner score) and radiological (e.g. axis deviation, secondary loss of realignment) follow-ups were conducted one and six weeks, as well as three, six, and 12 months after the operation.

RESULTS

This study comprises data of 27 patients (8 male, 19 female; 15 NCB®-DF, 12 LISS®). Polyaxial osteosynthesis using the NCB® system tended to result in better functional knee scores and a higher range of motion. Interestingly, fracture union tended to be more rapid using the polyaxial plating system.

CONCLUSIONS

We present the analysis of a multicenter prospective RCT to compare the monoaxial LISS® vs. the polyaxial NCB®-DF treatment following complex fractures of the distal femur. NCB®-DF treatment tended to result in better functional and radiological outcomes than LISS® treatment.

LEVEL OF EVIDENCE

Level I.

Simultaneous periprosthetic acetabular fracture and contralateral B-type compression injury of the pelvic ring: a case report of a rare injury combination

The periprosthetic fracture of the acetabulum is a rare injury, and its management is only sporadically reported in the literature. A few case reports are available which mainly focus on periprosthetic acetabular fractures in the elderly population. In our case, a 32-year-old patient suffered from a periprosthetic acetabular fracture in combination with a pelvic ring injury following a high velocity accident. The fracture morphology allowed a salvage of the prosthesis with an open reduction and internal fixation with a good radiographic and functional outcome one year after trauma.