The pathogenesis of bone loss following total knee arthroplasty

Tibial metaphyseal cones combined with short stems perform as well as long stems in revision total knee arthroplasty

Backgrounds

There is uncertainty around optimal tibial stem length in revision total knee arthroplasty (rTKA) utilizing a tibial trabecular metal (TM) cone. The purpose of this study was to compare: (1) functional outcomes, (2) radiographic outcomes and (3) implant survivorship in rTKA utilizing TM cones combined with either short stems (SS) or long stems (LS) at minimum 2 years follow‐up.

Methods

In this retrospective, multi‐centre study, patients undergoing rTKA utilizing a TM cone between 2008 and 2019 were included. Patients were divided into: SS group (no diaphyseal engagement), and LS group (diaphyseal engagement). All relevant clinical charts and post‐operative radiographs were examined. Oxford Knee Score (OKS) and EuroQol‐5D (EQ‐5D‐5L) data were collected at most recent follow‐up.

Results

In total, 44 patients were included: 18 in the SS group and 26 in the LS group. The mean time of follow‐up was 4.0 years. Failure free survival was 94.4% for the SS group and 92.3% for the LS group. All failures were for prosthetic joint infections managed with debridement, antibiotics, and implant retention. At most recent follow‐up, 3 patients demonstrated radiographic signs of lucency (1 SS 2 LS, P = 1) and the mean OKS were 37 ± 4 and 36 ± 6 (P = 0.73) in the SS and LS groups, respectively.

Conclusion

Tibial SS combined with TM cones performed as well as LS in rTKA at minimum 2 years follow‐up. A tibial SS in combination with a TM cone is a reliable technique to achieve stable and durable fixation in rTKA.

Higher Risk of Loosening for a Four-Pegged TKA Tibial Baseplate Than for a Stemmed One: A Register-based Study

BACKGROUND

Modern modular implants allow surgeons to mix different combinations of components within the same brand. From 1999 to 2012, the NexGen®-CR Option femoral component, together with a NexGen® Option Stemmed tibial plate (stemmed baseplate), which uses a short central stem, was the most-frequently used NexGen® combination in the Swedish Knee Arthroplasty Register. However, from 1999 to 2012, the same femoral component was also used along with the NexGen® Precoat four-pegged tibial baseplate (pegged baseplate). Considering the difference in the fixation concepts for these two tibial baseplates, we wanted to study whether their revision rates differed.

QUESTIONS/PURPOSES

To investigate the difference in (1) all-cause revision and (2) the risk of revision for aseptic loosening between the NexGen® pegged and stemmed baseplates when used with the NG-CR Option femoral component and the same two types of inserts.

METHODS

The Swedish Knee Arthroplasty Register provided data. The register, which was started in 1975, has since 1999 registered part numbers for individual implant components, allowing it to assess the combinations of components used in each patient. It has been shown to have high completeness (97%) and validity [12, 15]. The inclusion period was 1999 to 2012; during that time, 137,143 primary knee arthroplasties were registered, of which 125,094 were TKAs. Only TKAs performed for osteoarthritis and without patellar resurfacing were included, since not resurfacing the patella is the standard procedure in Sweden. This left 15,287 knees with the stemmed baseplate and 2479 with the pegged baseplate, or 12% and 2% of the total number of TKAs, respectively. Two general hospitals used the pegged baseplate exclusively during that period. Thus, specific patients were not selected for having the pegged plate. The mean age, mortality, and length of followup were similar for the two groups.We used the Kaplan-Meier statistics to calculate the cumulative revision rate (CRR) and Cox regression to compare risk ratios after adjusting for age and sex. The end point was a knee revision for respective all causes or aseptic loosening. The study ended on December 31, 2016. Due to the free healthcare system in Sweden it is highly unusual for patients to seek elective revision abroad, and by use of the extensive Swedish census register, we estimate the level of followup approximately 97%.

RESULTS

Knees with the pegged baseplate had a higher risk for all-cause revision than did those with the stemmed baseplate (5.8% [95% confidence interval {CI}, 4-8.3] and 3% [95% CI, 2.6-3.5] at 15 years; p = 0.003). After controlling for age and sex, the aseptic loosening risk in the pegged baseplate group was still higher than that in the stemmed group (relative risk, 5.40; 95% CI, 3.64-8.02; p < 0.001).

CONCLUSIONS

In this Swedish registry study, we observed a higher loosening risk with the pegged baseplate than the stemmed one, even after controlling for age and sex. Because this was only a comparison of implants from one vendor, and because there may have been other between-group differences for which we could not fully control, this concerning finding should be explored using data from other registries.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Mid-term results of impaction bone grafting in tibial bone defects in complex primary knee arthroplasty for severe varus deformity

Introduction: Bone defects are a challenging problem encountered occasionally during primary knee arthroplasty. These defects should be meticulously addressed so as to avoid malalignment and premature loosening and failure. Out of the many options available to deal with these defects, impaction bone grafting provides a more biological solution, which is especially important in case of primary knees.

Materials and methods: A retrospective analysis was done and patients with severe varus deformity of more than 20 degrees who had undergone primary knee arthroplasty with impaction bone grafting of the tibial condyle defect were followed up.

Results: Between 2008 and 2014, out of the 1124 patients who underwent primary total knee arthroplasty, only 26 knees in 23 patients met the inclusion criteria. The amount of varus deformity ranged from 20 to 35 degrees. Follow-up ranged from 3 to 8 years with an average of 6 years. The average pre-operative Knee Society Score (KSS) and Western Ontario McMaster Universities (WOMAC) score were 24.2 and 78, respectively. There were significant improvements in the post-op scores, with the average KSS being 90.2 and the WOMAC being 38.

Conclusion: Impaction bone grafting provides an invaluable option to the orthopedic surgeon for managing bone defects, especially in case of primary knee arthroplasty as it reconstitutes the bone stock.

How to reduce osteopenia in total knee arthroplasty?

BACKGROUND

Osteopenia of the front half of the distal femur is a well-known problem after total knee arthroplasty (TKA) with secondary issues after years, especially when must be addressed fractures or revisions for loosening. Stress shielding has been recognized as a cause in different biomechanical studies of the bone.

QUESTION/PURPOSES

It was logical to look for a solution by changing the design to minimize stress shielding behind the femoral shield.

PATIENTS AND METHODS

It was proved that radiological measure of bone density was reliable although not so early and accurate as densitometry. We used a shield without posterior fixation of the trochlea in a series of 21 TKA with radiological measures, preoperative, at 3 months and at 5 years. We compared the results with those of a series of classical TKA in the same category of age and sex.

RESULTS

The TKA without trochlea posterior fixation presented a significantly reduced osteopenia compared to the classical design of the femoral shield.

CONCLUSION

It seems that the non-fixation of the posterior surface of the trochlea may reduce osteopenia in TKA and so the risk of fractures and complications when revision surgery.

LEVEL OF EVIDENCE

2a.

Bone Remodeling of the Distal Femur After Uncemented Total Knee Arthroplasty-A 2-Year Prospective DXA Study

Loss of bone stock as a response to the bone trauma, immobilization, and stress shielding related to joint replacement surgery increases the risk of fracture of the distal femur after total knee arthroplasty. Previous studies of uncemented femoral components have reported very high levels of bone loss in the distal femur. This study investigates the adaptive bone remodeling of the distal femur after uncemented total knee arthroplasty. We performed a 2-year follow-up of 53 patients (mean age 61.5 [38-70] years, F/M = 27/26, body mass index 29.5) who because of osteoarthritis received an uncemented total knee arthroplasty. All patients received a NexGen CR-Flex Porous Femoral Component. Measurements of bone mineral density of the distal femur using dual-energy X-ray absorptiometry were performed postoperatively and after 3, 6, 12, and 24 months. Bone mineral density (g/cm²) was measured in 3 regions of interest in the periprosthetic bone of the distal femur. Repeated measures analysis of variance and Tukey post hoc test for bone mineral density changed over time (p < 0.05 were considered significant). In the distal femur, significant changes in bone mineral density were seen after 24 months of follow-up, and bone mineral density decreased by 23.6% in the anterior region behind the anterior flange of the prosthesis (p < 0.001), 10.1% in the posterior region (p < 0.001), and 5.5% in the most proximal region (p < 0.001). We found highly significant bone mineral change in the distal femur after uncemented total knee arthroplasty, most pronounced in the anterior region, where a decrease in bone mineral density of almost 25%, was seen. Taking the expected age-related decay in bone mineral density in this age group into consideration, the decrease was substantial and must be considered to predispose to periprosthetic fractures.

Does a PEEK Femoral TKA Implant Preserve Intact Femoral Surface Strains Compared With CoCr? A Preliminary Laboratory Study

BACKGROUND

Both the material and geometry of a total knee arthroplasty (TKA) component influence the induced periprosthetic bone strain field. Strain, a measure of the local relative deformation in a structure, corresponds to the mechanical stimulus that governs bone remodeling and is therefore a useful in vitro biomechanical measure for assessing the response of bone to new implant designs and materials. A polyetheretherketone (PEEK) femoral implant has the potential to promote bone strains closer to that of natural bone as a result of its low elastic modulus compared with cobalt-chromium (CoCr).

QUESTIONS/PURPOSES

In the present study, we used a Digital Image Correlation (DIC) technique to answer the following question: Does a PEEK TKA femoral component induce a more physiologically normal bone strain distribution than a CoCr component? To achieve this, a DIC test protocol was developed for periprosthetic bone strain assessment using an analog model; the protocol aimed to minimize errors in strain assessment through the selection of appropriate analysis parameters.

METHODS

Three synthetic bone femurs were used in this experiment. One was implanted with a CoCr femoral component and one with a PEEK femoral component. The third (unimplanted) femur was intact and used as the physiological reference (control) model. All models were subjected to standing loads on the corresponding polyethylene (ultrahigh-molecular-weight polyethylene) tibial component, and speckle image data were acquired for surface strain analysis using DIC in six repeat tests. The strain in 16 regions of interest on the lateral surface of each of the implanted bone models was plotted for comparison with the corresponding strains in the intact case. A Wilcoxon signed-rank test was used to test for difference at the 5% significance level.

RESULTS

Surface analog bone strain after CoCr implantation indicated strain shielding (R² = 0.6178 with slope, β = 0.4314) and was lower than the intact case (p = 0.014). The strain after implantation with the PEEK implant deviated less from the intact case (R² = 0.7972 with slope β = 0.939) with no difference (p = 0.231).

CONCLUSIONS

The strain shielding observed with the contemporary CoCr implant, consistent with clinical bone mineral density change data reported by others, may be reduced by using a PEEK implant.

CLINICAL RELEVANCE

This bone analog in vitro study suggests that a PEEK femoral component could transfer more physiologically normal bone strains with a potentially reduced stress shielding effect, which may improve long-term bone preservation. Additional studies including paired cadaver tests are necessary to test the hypothesis further.

The role of the design of tibial components and stems in knee replacement

Stems improve the mechanical stability of tibial components in total knee replacement (TKR), but come at a cost of stress shielding along their length. Their advantages include resistance to shear, reduced tibial lift-off and increased stability by reducing micromotion. Longer stems may have disadvantages including stress shielding along the length of the stem with associated reduction in bone density and a theoretical risk of subsidence and loosening, peri-prosthetic fracture and end-of-stem pain. These features make long stems unattractive in the primary TKR setting, but often desirable in revision surgery with bone loss and instability. In the revision scenario, stems are beneficial in order to convey structural stability to the construct and protect the reconstruction of bony defects. Cemented and uncemented long stemmed implants have different roles depending on the nature of the bone loss involved.

This review discusses the biomechanics of the design of tibial components and stems to inform the selection of the component and the technique of implantation.

Periprosthetic tibial bone mineral density changes after total knee arthroplastyOne-year follow-up study of 69 patients

BACKGROUND

The critical structure supporting the prosthetic components in total knee arthroplasty (TKA) is tibial trabecular bone. The quality of tibial bone can be evaluated by bone mineral density (BMD) measurements.

PATIENTS AND METHODS

We prospectively measured changes in BMD in the proximal tibia after cemented TKA in osteoarthrotic knees. 69 patients were scanned by dual-energy X-ray absorptiometry (DXA) within a week after surgery, and after 3, 6 and 12 months.

RESULTS

At baseline, the medial region of interest (ROI) BMD was higher in the varus knees than in the valgus aligned knees (p=0.02). The medial metaphyseal ROI showed a decrease in BMD during the follow-up in preoperatively varus knee joints (p<0.001). In preoperatively valgus knees, there was a slight increase in medial compartment BMD which was not significant (p=0.2). Alignment correction in both groups showed bone remodeling giving similar medial and lateral BMD values, suggesting that the bone became equally strong in both compartments of the metaphysis. There was no association between increasing American Knee Society (AKS) scores and bone remodeling.

INTERPRETATION

We suggest that this remodeling is caused by postoperative changes in tibial loading. Our results support the clinical importance of recreating proper valgus alignment of the knee joint in the TKA operation, thus possibly providing better conditions for longevity of the tibial component.

Radiographic prediction of intraoperative bone loss in knee arthroplasty revision

A key challenge for orthopaedic surgeons performing revision total knee arthroplasty is the management of bone loss. The goal of our study was to test the validity of predicting bone loss from preoperative radiographs using two commonly utilized bone loss assessments: the Anderson Orthopaedic Research Institute and University of Pennsylvania systems and secondarily to assess the frequency and severity of bone loss in a prospective study of total knee arthroplasty revisions. Ninety-eight total knee arthroplasty revision patients were assessed and bone loss was detected in 76 (77.6%) patients preoperatively and intraoperatively. The validity of both systems was established. Agreement between preoperative and intraoperative Anderson Orthopaedic Research Institute classification was fair for the femur and good for the tibia. All University of Pennsylvania preoperative measures were correlated with intraoperative measures. Establishing valid and reliable preoperative systems of measuring bone loss facilitates planning of total knee arthroplasty revision and rehabilitation and meaningful comparisons between different series of patients and treatment protocols.

LEVEL OF EVIDENCE

Diagnostic study, level I (prospective testing of previously developed diagnostic criteria on consecutive patients [with universally applied reference "gold" standard]). See Author Guidelines for a complete description of levels of evidence.

Mechanical Interlocking of Engineered Cartilage to an Underlying Polymeric Substrate: Towards a Biohybrid Tissue Equivalent

This study investigates the feasibility of engineering a biohybrid cartilage equivalent (BCE) with the long-term goal of restoring the mechanical integrity and interfacial characteristics of severely damaged cartilage. The BCE depends on the successful adhesion, via mechanical interlocking, of a cartilage layer to a nondegradable composite scaffold or prosthesis. The model scaffold, consisting of a nonwoven mesh bonded to a solid core, was seeded with bovine articular chondrocytes. High molecular weight poly(L-lactic acid), which has a slow degradation time, was used to model the nondegradable polymer. Biochemical and histological analysis demonstrate that the BCE can support the growth of a cartilaginous matrix for at least 6 weeks in culture. Mechanical testing of the BCE showed cartilage adhesion strength increased from 19.27+/-1.62 to 43.79+/-3.88 kPa between 35 and 50 days in culture. Nonmechanically interlocked cartilage achieved less than 5% of this adhesion strength. For the first time, atomic force microscopy (AFM) was used to characterize surface topography of tissue-engineered cartilage. Surface roughness of constructs after 8 and 10 weeks ranged from 153 to 171 nm, falling within the range of native cartilage (100-600 nm). This study demonstrates the feasibility of creating a biohybrid cartilage equivalent by mechanically interlocking a cartilaginous layer to an underlying polymeric matrix.

Impaction bone-grafting in revision joint replacement surgery

The standard graft material for impaction bone-grafting is fresh-frozen femoral head allograft morselized to a particle size as large as is practical to ensure stability and allow new bone formation. The graft must be sufficiently compacted to provide immediate mechanical stability; this requires containment of the graft and substantial impaction energy. Diaphyseal bone fracture and excessive implant migration are the most common complications of the operation. Impaction bone-grafting in revision total hip replacement has produced good medium-term results on both the acetabular and the femoral side. The use of compacted morselized bone graft is a relatively new technique in revision knee surgery and requires longer-term follow-up with larger numbers of patients to assess its value.

Periprosthetic femoral bone loss after total knee arthroplasty: 1-year follow-up study of 69 patients

The clinical survival of joint arthroplasties is related to the quality of the surrounding bone environment. Bone mineral density (BMD) is an important measure of bone strength and quality. The aim of this prospective study was to measure the quantitative changes in BMD in the distal femur after cemented total knee arthroplasty (TKA) in osteoarthrotic knee joints. Sixty-nine patients with TKA were scanned postoperatively using dual-energy X-ray absorptiometry (DXA) within a week of surgery, and at 3-, 6-, and 12-month follow-ups. An average decrease in bone density of 17.1% (mean range of 12.1-22.8%) was measured adjacent to the prosthesis at the 12-month follow-up (repeated measures ANOVA P<0.0005). Bone loss was most rapid during the first 3 months after TKA. The clinical status and function parameters of the knee joint, evaluated by the American Knee Society (AKS) score, had improved significantly on the preoperative values at the three- and 12-month follow-ups (P<0.0005). However, improvement in the AKS score was not associated with periprosthetic BMD change (P=0.204), whereas age (P=0.067) and body mass index (P=0.019) correlated with BMD loss for the total metaphyseal region of interest (ROI), by repeated measures ANOVA. We suggest that the observed periprosthetic bone loss was mainly the result of prosthesis-related stress-shielding.

Underestimation of osteolysis in posterior stabilized total knee arthroplasty

Periprosthetic osteolysis in total knee arthroplasty (TKA) has become a significant problem. Routine surveillance is warranted to detect problems that may not be symptomatic. The goal of these radiographs is to detect arthroplasty-related bone loss at an early stage to implement strategies to limit its extension. The purpose of this study was to show the extent to which condylar osteolysis can be underestimated on routine radiographs. Two cadaveric femurs were prepared to receive a posterior stabilized (PS) femoral component. A simulated osteolytic lesion was created using acetabular reamers. Lesions of 36 mm not easily discernible on standard anteroposterior and lateral images were easily recognized on oblique films. The oblique radiographs described can help with the early recognition of retrofemoral osteolysis about a posterior-stabilized implant.

Long stemmed total knee arthroplasty with interlocking screws: a computational bone adaptation study

The ability of an interlocking screw fixation technique to minimize bone loss related to stress shielding in the tibia was investigated and compared to the abilities of cement and press-fit fixation. Full bony ingrowth has been associated with greater stress shielding than partial ingrowth; therefore, the effect of intimate bonding of the stem to bone on subsequent bone loss was also studied. A damage- and disuse-based remodeling theory was coupled with a two-dimensional finite element model of the tibia to predict changes in bone remodeling following long stemmed total knee arthroplasty (TKA) for four different fixation techniques (cement, press-fit, interlock with bony ingrowth, and interlock without bony ingrowth). Remodeling changes commenced with the model state variables--bone area fraction, mechanical stimulus, damage, and remodeling activity--at steady-state values predicted by the intact tibia simulation. After TKA and irrespective of fixation technique, the model predicted elevated remodeling due to disuse, in which more bone was removed than replenished. In regions below the tibial tray and along the cortices, the interlocking stem with full bony ingrowth and the cemented stem caused the least amount of bone loss. An interlocking stem with a smooth, matted finish did not reduce the bone loss associated with interlocking fixation.

Bone formation is not impaired by hibernation (disuse) in black bears Ursus americanus

Disuse by bed rest, limb immobilization or space flight causes rapid bone loss by arresting bone formation and accelerating bone resorption. This net bone loss increases the risk of fracture upon remobilization. Bone loss also occurs in hibernating ground squirrels, golden hamsters, and little brown bats by arresting bone formation and accelerating bone resorption. There is some histological evidence to suggest that black bears Ursus americanus do not lose bone mass during hibernation (i.e. disuse). There is also evidence suggesting that muscle mass and strength are preserved in black bears during hibernation. The question of whether bears can prevent bone loss during hibernation has not been conclusively answered. The goal of the current study was to further assess bone metabolism in hibernating black bears. Using the same serum markers of bone remodeling used to evaluate human patients with osteoporosis, we assayed serum from five black bears, collected every 10 days over a 196-day period, for bone resorption and formation markers. Here we show that bone resorption remains elevated over the entire hibernation period compared to the pre-hibernation period, but osteoblastic bone formation is not impaired by hibernation and is rapidly accelerated during remobilization following hibernation.

Osteointegration and implant position after cementless total knee replacement

Osteointegration and implant position are regions of interest after cementless total knee replacement. The radiographic and functional status of 101 implants in 101 patients were evaluated 3, 12, and 24 months after implantation. To obtain satisfactory radiographs, a fluoroscopically assisted technique was used. In 92% of tibia interfaces, at least one wedge-shaped radiolucent area was visible without measurable changes of component position. The width of the gap increased from the central tibial area to the periphery. The shape was determined 3 months postoperatively. The femur could not be assessed for radiolucency because of the central metal crest design. In the current study, regularly appearing wedge-shaped radiolucent areas at the tibia interface, with the maximal width at the periphery, did not indicate aseptic loosening but showed that the forces of displacement had overcome initial mechanical stability, inducing micromotion of the implant. Osteointegration was seen only in central regions of the implant with minimal micromotion. Within the first year, partial bone ingrowth, fibrous fixation, and the surrounding bone gave satisfactory stability to provide secure fixation of the implant.

Serum markers of bone metabolism show bone loss in hibernating bears

Disuse osteopenia was studied in hibernating black bears (Ursus americanus) using serum markers of bone metabolism. Blood samples were collected from male and female, wild black bears during winter denning and active summer periods. Radioimmunoassays were done to determine serum concentrations of cortisol, the carboxy-terminal cross-linked telopeptide, and the carboxy-terminal propeptide of Type I procollagen, which are markers of bone resorption and formation, respectively. The bone resorption marker was significantly higher during winter hibernation than it was in the active summer months, but the bone formation marker was unchanged, suggesting an imbalance in bone remodeling and a net bone loss during disuse. Serum cortisol was significantly correlated with the bone resorption marker, but not with the bone formation marker. The bone formation marker was four- to fivefold higher in an adolescent and a 17-year-old bear early in the remobilization period compared with the later summer months. These findings raise the possibility that hibernating black bears may minimize bone loss during disuse by maintaining osteoblastic function and have a more efficient compensatory mechanism for recovering immobilization-induced bone loss than that of humans or other animals.

Periprosthetic fracture of the tibia associated with osteolysis caused by failure of rotating patella in low-contact-stress total knee arthroplasty

Periprosthetic fracture of the tibial plateau associated with osteolysis resulting from mechanical failure of the rotating patellar component after total knee arthroplasty with the New Jersey Low-Contact-Stress (LCS) knee (DePuy, Warsaw, IN) has not been reported previously. A 67-year-old woman with rheumatoid arthritis of the left knee had a LCS prosthesis implanted without cement, using a rotating patellar component. Seven years later, a fracture of the lateral tibial plateau occurred owing to an osteolytic defect with no traumatic accident. The rotating patellar bearing over-rotated and locked; consequently, wear occurred between the patellar metal tray and the femoral component. Immunohistochemistry revealed CD68-positive macrophages in the osteolytic region and phagocytosis of metal particles. The osteolytic region was filled with autogenous bone, and all components were exchanged and cemented. The patient's condition became satisfactory with relief of pain.

Flow-induced calcium oscillations in rat osteoblasts are age, loading frequency, and shear stress dependent

Bone adaptation to mechanical loading is dependent on age and the frequency and magnitude of loading. It is believed that load-induced fluid flow in the porous spaces of bone is an important signal that influences bone cell metabolism and bone adaptation. We used fluid flow-induced shear stress as a mechanical stimulus to study intracellular calcium (Ca) signaling in rat osteoblastic cells (ROB) isolated from young, mature, and old animals. Fluid flow produced higher magnitude and more abundant [Ca(2+)](i) oscillations than spontaneous oscillations, suggesting that flow-induced Ca signaling encodes a different cellular message than spontaneous oscillations. ROB from old rats showed less basal [Ca(2+)](i) activity and were less responsive to fluid flow. Cells were more responsive to 0.2 Hz than to 1 or 2 Hz and to 2 Pa than to 1 Pa. These data suggest that the frequency and magnitude of mechanical loading may be encoded by the percentage of cells displaying [Ca(2+)](i) oscillations but that the ability to transduce this information may be altered with age.

Early failure associated with the use of Hylamer-M spacers in three primary AMK total knee arthroplasties

We report 3 cases of early failure associated with AMK total knee arthroplasties with the use of Hylamer-M spacers. In 2 of these cases, massive osteolysis of the posterior condyles was noted; revision with the use of allograft bone to fill in the cavitary defects yielded excellent results. In all cases, large areas of pitting and delamination of the Hylamer spacers were noted. Given these cases and the previous literature on early failure of hip arthroplasties with Hylamer inserts, we recommend caution in using Hylamer for knee arthroplasty surgery.

The prevention of periprosthetic fractures in total hip and knee arthroplasty

Periprosthetic fractures in total hip and total knee arthroplasty lead to considerable morbidity in terms of component fixation, bone loss, and subsequent function. The management of these fractures is technically demanding and may result in suboptimal fixation owing to poor bone stock. The prevention, early recognition, and appropriate management of such fractures are therefore critical. The pathogenesis of periprosthetic factors is multifactorial. There are a number of intrinsic patient influences such as bone stock, biomechanics, and compliance. There are also a host of extrinsic factors over which the surgeon has more control. The prevention of periprosthetic fractures requires careful preoperative planning and templating, the availability of the necessary expertise and equipment, and knowledge of the potential pitfalls so that these can be avoided both intraoperatively and in follow-up.