Is TKA femoral implant stability improved by pressure applied cement? a comparison of 2 cementing techniques

BACKGROUND

The majority of knee endoprostheses are cemented. In an earlier study the effects of different cementing techniques on cement penetration were evaluated using a Sawbone model. In this study we used a human cadaver model to study the effect of different cementing techniques on relative motion between the implant and the femoral shaft component under dynamic loading.

METHODS

Two different cementing techniques were tested in a group of 15 pairs of human fresh frozen legs. In one group a conventional cementation technique was used and, in another group, cementation was done using a pressurizing technique. Under dynamic loading that simulated real life conditions relative motion at the bone-implant interface were studied at 20 degrees and 50 degrees flexion.

RESULTS

In both scenarios, the relative motion anterior was significantly increased by pressure application. Distally, it was the same with higher loads. No significant difference could be measured posteriorly at 20°. At 50° flexion, however, pressurization reduced the posterior relative motion significantly at each load level.

CONCLUSION

The use of the pressurizer does not improve the overall fixation compared to an adequate manual cement application. The change depends on the loading, flexion angle and varies in its proportion in between the interface zones.

[Treatment of hip dysplasia in young adults]

Developmental dysplasia of the hip (DDH) is one of the most common disorders of hips in children. The deformity can remain asymptomatic into adolescence and adulthood; however, it is considered to be a form of prearthritis and is the main cause of premature osteoarthritis of the hip. The deformity affects the acetabulum but can also be accompanied by changes in the shape of the proximal femur. If conservative treatment for mild DDH is insufficient, or in cases of moderate to severe DDH, operative treatment should be carried out, for example by corrective osteotomy of the pelvis and/or the proximal femur and hip arthroscopy may be considered adjunctively in order to resolve the prearthritis and prevent premature osteoarthritis of the hip. This manuscript elucidates the deformity, the diagnostic measures required to make the diagnosis and the treatment options available for prevention of arthritis.

Transversal Malalignment and Proximal Involvement Play a Relevant Role in Unilateral Cerebral Palsy Regardless the Subtype

Classification of gait disorders in cerebral palsy (CP) remains challenging. The Winters, Gage, and Hicks (WGH) is a commonly used classification system for unilateral CP regarding the gait patterns (lower limb kinematics) solely in the sagittal plane. Due to the high number of unclassified patients, this classification system might fail to depict all gait disorders accurately. As the information on trunk/pelvic movements, frontal and transverse planes, and kinetics are disregarded in WGH, 3D instrumented gait analysis (IGA) for further characterization is necessary. The objective of this study was a detailed analysis of patients with unilateral CP using IGA taking all planes/degrees of freedom into account including pelvic and trunk movements. A total of 89 individuals with unilateral CP matched the inclusion criteria and were classified by WGH. Subtype-specific differences were analyzed. The most remarkable findings, in addition to the established WGH subtype-specific deviations, were pelvic obliquity and pelvic retraction in all WGH types. Furthermore, the unclassified individuals showed altered hip rotation moments and pelvic retraction almost throughout the whole gait cycle. Transversal malalignment and proximal involvement are relevant in all individuals with unilateral CP. Further studies should focus on WGH type-specific rotational malalignment assessment (static vs. dynamic, femoral vs. tibial) including therapeutic effects and potential subtype-specific compensation mechanisms and/or tertiary deviations of the sound limb.

Femoral Cementation in Knee Arthroplasty-A Comparison of Three Cementing Techniques in a Sawbone Model Using the ATTUNE Knee

Femoral component loosening is a rare but severe complication in total knee arthroplasty. Former studies have repeatedly demonstrated radiolucent lines behind the ventral and dorsal anchoring shields of the femoral components, which has led us to investigate this matter further. Therefore, three different cementing techniques were tested in a group of nine Sawbone samples each. These differed in the amount of cement applied on the femoral component as well as in the pressure application. Computed tomography was performed to evaluate and classify the cement penetration into the bone adjacent to the prosthesis according to the zones defined by the Knee Society scoring system. The results show significantly deeper cement penetration in all zones when a pressurizer is used. In the other two groups, no significant difference in the dorsal bevel cement penetration was noted. Additionally, no difference in ventral and dorsal cement penetrations (Zones 1 and 4) was delineated. In contrast, there was a significant difference in both the ventral bevel (Zone 2) as well as the distal anchoring surface (Zones 5-7). The use of a pressurizer results in greater cement penetration into all anchoring areas. Completely covering the component back surface results in a significantly higher penetration, which is mainly due to differences in volume. These data show significantly improved cementation results when using a pressurizer. Whether this improves the biomechanical properties and ultimately the revision rate requires further investigation.

Sialendoscopy and Sjogren's Disease: A Systematic Review

OBJECTIVES/HYPOTHESIS

This study is a systematic review of the literature which seeks to estimate the expected treatment outcomes of a patient with Sjogren's syndrome (SS) undergoing therapeutic sialendoscopy.

STUDY DESIGN

Systematic Review.

METHODS

PubMed, Scopus, and Cochrane library databases were used to search for studies published as of August 2020 regarding the treatment outcomes of SS with sialendoscopy. The key search terms included "Sjogren's syndrome" and "sialendoscopy." Only studies in the English language involving more than one human patient were included. PRISMA guidelines were followed in study inclusion and data extraction. The primary outcome assessed was improvement in patient symptoms.

RESULTS

Six studies met criteria and were analyzed in this review, including 125 patients undergoing sialendoscopy of parotid and/or submandibular glands as well as 25 controls. Of these patients, 90% were female with an age range of 18 to 79 years. There was significant diversity in outcome reporting tools. The outcomes of symptom improvement were pooled qualitatively based on improvement noted in each study. Outcomes were defined as partial improvement if the measured outcomes improved and complete improvement if measured outcomes resolved entirely. Despite the limited number of studies on this topic, this meta-analysis suggests that a similar study of therapeutic sialendoscopy could expect to provide at least temporary improvement of symptoms 90% to 99% of the time.

CONCLUSIONS

This review provides support for the application of sialendoscopy in the treatment of SS salivary disease. Larger studies with consistent outcome reporting tools and control groups are needed to validate these results and provide a consistent therapy protocol. Laryngoscope, 131:1474-1481, 2021.

Revision of a blade cut-out in PFN-A fixation: Blade exchange, cement augmentation and a cement plug as a successful salvage option

A potential and feared complication of proximal femur nails with cephalomedullary fixation is migration of the cephalomedullary screw or blade (cut-out or cut-through). In patients not suitable (e.g. low demand, comorbidities) for conversion to total hip arthroplasty blade exchange with cement augmentation may be an option. This article describes the first successful clinical use of a salvage procedure of a previously published technique, which allows the surgeon to avoid intraarticular cement leakage by using a standard cement plug to close the defect in the femoral head.

Comparison of the Primary Stability of Porous Tantalum and Titanium Acetabular Revision Constructs

Adequate primary stability of the acetabular revision construct is necessary for long-term implant survival. The difference in primary stability between tantalum and titanium components is unclear. Six composite hemipelvises with an acetabular defect were implanted with a tantalum augment and cup, using cement fixation between cup and augment. Relative motion was measured at cup/bone, cup/augment and bone/augment interfaces at three load levels; the results were compared to the relative motion measured at the same interfaces of a titanium cup/augment construct of identical dimensions, also implanted into composite bone. The implants showed little relative motion at all load levels between the augment and cup. At the bone/augment and bone/cup interfaces the titanium implants showed less relative motion than tantalum at 30% load (p < 0.001), but more relative motion at 50% (p = n.s.) and 100% (p < 0001) load. The load did not have a significant effect at the augment/cup interface (p = 0.086); it did have a significant effect on relative motion of both implant materials at bone/cup and bone/augment interfaces (p < 0.001). All interfaces of both constructs displayed relative motion that should permit osseointegration. Tantalum, however, may provide a greater degree of primary stability at higher loads than titanium. The clinical implication is yet to be seen

Comparison of Different Locking Mechanisms in Total Hip Arthroplasty: Relative Motion between Cup and Inlay

The resulting inflammatory reaction to polyethylene (PE) wear debris, which may result in osteolysis, is still considered to be a main reason for aseptic loosening. In addition to the primary wear in hip joint replacements caused by head-insert articulation, relative motions between the PE liner and the metal cup may cause additional wear. In order to limit this motion, various locking mechanisms were used. We investigated three different locking mechanisms (Aesculap, DePuy, and Zimmer Biomet) to address the resulting relative motion between the acetabular cup and PE liner and the maximum disassembly force. A standardized setting with increasing load levels was used in combination with optically based three-dimensional measurements. In addition the maximum disassembly forces were evaluated according to the ASTM F1820-13 standard. Our data showed significant differences between the groups, with a maximum relative motion at the maximum load level (3.5 kN) of 86.5 ± 32.7 µm. The maximum axial disassembly force was 473.8 ± 94.6 N. The in vitro study showed that various locking mechanisms may influence cup-inlay stability.

Trimodal embolization of juvenile nasopharyngeal angiofibroma with intracranial extension

OBJECTIVES/PURPOSE

1. Understand three different techniques for embolization of juvenile nasal angiofibroma (JNA) and assess their combined efficacy. 2. Perform successful endoscopic intralesional embolization of highly vascular sinonasal neoplasms.

METHODS

In this study, we present the case of a 10-year-old male patient diagnosed with juvenile nasal angiofibroma (JNA) who successfully underwent trimodal embolization and resection at a tertiary academic medical center after failed coil embolization in his home country. We examine the clinical details of the case and a review of pertinent literature.

RESULTS

Preoperative embolization is common in the treatment of JNA, but there is little consensus as to the proper timeframe and techniques utilized. In our case, preoperative imaging revealed a vascular tumor with intracranial extension consistent with UPMC Stage V JNA. Diagnostic angiogram revealed significant arborization from the internal and external carotid systems. A trimodal embolization technique, utilizing transarterial, percutaneous, and direct endoscopic intralesional injection of n-Butyl Cyanoacrylate (n-BCA) was performed. A two-staged endoscopic and open resection was subsequently performed one week later with minimal blood loss. In our case, combining intralesional embolization with traditional transarterial techniques resulted in an improved operative field and a successful clinical result.

CONCLUSION

Embolization of highly vascular sinonasal tumors with n-BCA is not limited to endovascular techniques, but can be safely combined with percutaneous and endoscopic intralesional embolization up to one week prior to surgical resection.

Titanium Acetabular Component Deformation under Cyclic Loading

Acetabular cup deformation may affect liner/cup congruency, clearance and/or osseointegration. It is unclear, whether deformation of the acetabular components occurs during load and to what extent. To evaluate this, revision multi-hole cups were implanted into six cadaver hemipelvises in two scenarios: without acetabular defect (ND); with a large acetabular defect (LD) that was treated with an augment. In the LD scenario, the cup and augment were attached to the bone and each other with screws. Subsequently, the implanted hemipelvises were loaded under a physiologic partial-weight-bearing modality. The deformation of the acetabular components was determined using a best-fit algorithm. The statistical evaluation involved repeated-measures ANOVA. The mean elastic distension of the ND cup was 292.9 µm (SD 12.2 µm); in the LD scenario, 43.7 µm (SD 11.2 µm); the mean maximal augment distension was 79.6 µm (SD 21.6 µm). A significant difference between the maximal distension of the cups in both scenarios was noted (F(1, 10) = 11.404; p = 0.007). No significant difference was noted between the compression of the ND and LD cups, nor between LD cups and LD augments. The LD cup displayed significantly lower elastic distension than the ND cup, most likely due to increased stiffness from the affixed augment and screw fixation.

Obesity, depression and hip pain

INTRODUCTION

Up to 64% of the general population reports experiencing chronic pain, with the hip being one of the most frequent sites. An association has been shown between chronic back pain, obesity and depression. To date, a similar association has not been investigated with chronic hip pain.

METHODS

A total of 2,515 subjects were chosen as a representative cross-section of the German population. Each was provided with a questionnaire that included the Regional Pain Scale, European Organization for Research and Treatment of Cancer Quality of Life Questionnaire (EORTC QLQ-C30), Beck Depression Inventory-Primary Care and Winkler social class index. Participant height and weight values were obtained from self-reports. Using logistic regression methodology, we analysed the association between hip pain, obesity and increased depression scores.

RESULTS

A total of 124 (4.9%) subjects reported chronic hip pain and an additional 39 (1.5%) reported chronic hip pain that was disabling. Hip pain affected 1-5 sites (oligolocular) in 47% of cases, and was widespread (6-19 sites) in 50%. Obesity and increased values on the depression scale were associated with an increased likelihood of chronic hip pain (odds ratio [OR] 2.55 and 8.53, respectively) compared with subjects without pain. Increased values on the depression scale (OR 28.22) increased the likelihood of experiencing disabling chronic hip pain in comparison with pain free individuals.

CONCLUSIONS

Hip pain is rarely the sole site of pain. Obesity and increased values on the depression scale are associated with chronic hip pain. Increased values on the depression scale are associated with disabling chronic hip pain.

Long-Term Results of Acetabular Reconstruction Using Ganz Acetabular Rings

BACKGROUND

Our study examines the long-term results of acetabular reconstruction using the Ganz acetabular reinforcement ring (GRR) in total hip arthroplasty.

METHODS

Between 1998 and 2001, 135 hips (119 revision and 16 primary arthroplasties) were consecutively implanted with a GRR at our hospital. The average age was 65 years (range, 26-90). Clinical and radiographic evaluations were carried out. Long-term survivorship was estimated using a competing risks analysis, and multivariate survivorship using Cox regression model was used to identify risk factors for implant failure.

RESULTS

At a mean follow-up of 16 years (range, 15-18), 3 patients were lost to follow-up and 19 had implant failure: 4 aseptic loosenings without re-revision, 4 septic, and 11 aseptic re-revisions. Survival was estimated at 86% after 16 years (95% confidence interval [CI], 78.5%-90.9%) using radiographic loosening or revision for any reason as the end point. Using aseptic loosening as the end point, the survival was estimated at 91.2% after 16 years (95% CI, 84.5%-95.0%). Multivariate analysis revealed that age at surgery was a significant risk factor for failure of the GRR. With acetabular revision or loosening as the end point, patients ≤60 years had 71.6% (95% CI, 53%-82.8%) and older patients had 92.2% (95% CI, 84%-96.2%) probability of implant survival after a mean 16-year follow-up. The median Harris Hip Scores and Western Ontario and McMaster Universities Osteoarthritis Index scores were 77 and 64.5, respectively, and mean Numerical Pain Rating Scale score was 1.6 at final follow-up.

CONCLUSION

Our long-term study showed acceptable survival and functional results using the GRR in older patients, while young patients had less favorable survival.

Treatment of High-Grade Acetabular Defects: Do Porous Titanium Cups Provide Better Stability Than Traditional Titanium Cups When Combined With an Augment?

BACKGROUND

Revision total hip arthroplasty frequently faces challenges associated with deficient bone stock. Porous metal implants were developed to meet the challenge, but require rapid osseointegration for ultimate success. This study aims to assess relative motion as an indicator for primary stability and osseointegration of two different titanium cups each combined with a titanium augment.

METHODS

In 14 cadaver hemipelvises, 2 types of titanium acetabular cups, a traditional sintered-bead cup (POROCOAT Acetabular Cup [PAC]) and a newer porous-coated cup (GRIPTION Acetabular Cup [GAC]) each associated with a porous augment, were subjected to 3-dimensional varying loads, replicating 30% of loads experienced during normal gait. Relative motion was measured at the cup/bone, augment/bone, and cup/augment interfaces.

RESULTS

Only at the cup/bone interface was there a statistically significant difference in relative motion between the traditional PAC and the newer GAC, with PAC showing less relative motion (P = .0037). Bone mineral density (BMD) had a significant effect on relative motion (P = .0019) at the cup/bone interface of both cup types, with low BMD specimens showing more relative motion.

CONCLUSION

Both cup types combined with augments displayed minimal relative motion that was within the accepted range thought to allow osseointegration, although the traditional surface proved superior to the newer surface. This difference was more pronounced at low BMD, with the well-established PAC cup displaying less relative motion than the more porous GAC cup, consistent with better osseointegration than the more porous cup. This suggests that the more porous implant may be less advantageous than traditional PAC cups, particularly in cases with poorer bone stock.

Comparison of the stability of three fixation techniques between porous metal acetabular components and augments

Objectives

In order to address acetabular defects, porous metal revision acetabular components and augments have been developed, which require fixation to each other. The fixation technique that results in the smallest relative movement between the components, as well as its influence on the primary stability with the host bone, have not previously been determined.

Methods

A total of 18 composite hemipelvises with a Paprosky IIB defect were implanted using a porous titanium 56 mm multihole acetabular component and 1 cm augment. Each acetabular component and augment was affixed to the bone using two screws, while the method of fixation between the acetabular component and augment varied for the three groups of six hemipelvises: group S, screw fixation only; group SC, screw plus cement fixation; group C, cement fixation only. The implanted hemipelvises were cyclically loaded to three different loading maxima (0.5 kN, 0.9 kN, and 1.8 kN).

Results

Screw fixation alone resulted in up to three times more movement (p = 0.006), especially when load was increased to 100% (p < 0.001), than with the other two fixation methods (C and SC). No significant difference was noted when a screw was added to the cement fixation. Increased load resulted in increased relative movement between the interfaces in all fixation methods (p < 0.001).

Conclusion

Cement fixation between a porous titanium acetabular component and augment is associated with less relative movement than screw fixation alone for all implant interfaces, particularly with increasing loads. Adding a screw to the cement fixation did not offer any significant advantage. These results also show that the stability of the tested acetabular component/augment interface affects the stability of the construct that is affixed to the bone.Cite this article: N. A. Beckmann, R. G. Bitsch, M. Gondan, M. Schonhoff, S. Jaeger. Comparison of the stability of three fixation techniques between porous metal acetabular components and augments. Bone Joint Res 2018;7:282-288. DOI: 10.1302/2046-3758.74.BJR-2017-0198.R1.

Comparison of the Primary Stability of a Porous Coated Acetabular Revision Cup With a Standard Cup

BACKGROUND

The number of revision hip arthroplasty procedures has been increasing substantially, with the acetabular component requiring component revision in over half of the cases. New porous implant designs attempt to improve outcomes due to improved osseointegration; however, sufficient primary stability is paramount for good osseointegration.

METHODS

We compared 2 revision cups of the same geometry, yet different surface properties in an in vitro scenario: a porous titanium surface and a conventional sintered-bead titanium surface. These were tested in 10 cadaveric pelvises under a physiologic cyclic partial weight-bearing scenario. Each side was randomly implanted with one of the implants. Relative motion between the bone and cup was measured using an optical measuring device. Statistical evaluation was carried out descriptively using a covariance analysis with repeated measures and a test of fixed effects, with significance determined as P < .05.

RESULTS

The conventional cup displayed an average relative motion of 28.02 μm; and the porous implant displayed an average relative motion of 33.42 μm. There was no statistically significant difference between the two with regard to the resultant relative motion (P = .2649). The bone mineral density does have a significant influence on resultant relative motion (P = .0406), with higher bone mineral density correlating with less relative motion in both implants.

CONCLUSION

The porous implant provides similar primary stability to the conventional implant in the tested scenario; the motion of both implants relative to the bone was within safe limits for osseointegration. Bone stock must be considered when choosing implant type and postoperative care.

Bone remodelling around the Metha® short stem implant - Clinical and dual-energy x-ray absorptiometry (DXA) results

OBJECTIVE

Bony ingrowth of short stems is under investigation.

METHOD

Over one year bony reactions around the Metha^® stem were investigated using the DXA method in a standardized zonal system (19 ROIs). Clinical results were documented using the HHS.

RESULTS

HHS significantly improved from 46 points to 97 points. After one year bone marrow density (BMD) increased in the lateral distal and lateral proximal areas as well as in the mid medial area. BMD decreased in the proximal medial and mid lateral areas.

CONCLUSION

The concept of metaphyseal ingrowth was confirmed, but distal bony reactions need further investigation.

Core Decompression and Autologous Bone Marrow Concentrate for Treatment of Femoral Head Osteonecrosis: A Randomized Prospective Study

The aim of this study was to investigate the safety of injection of bone marrow aspirate concentrate during core decompression and to study its clinical (visual analogue scale; Harris-Hip-score) and radiological outcomes (magnetic resonance imaging). In this prospective and randomized clinical trial we evaluated 24 consecutive patients with non-traumatic femoral head necrosis (FHN) during a period of two years after intervention. In vitro analysis of mesenchymal stem cells was performed by evaluating the fibroblast colony forming units (CFU-Fs). Postoperatively, significant decrease in pain associated with a functional benefit lasting was observed. However, there was no difference in the clinical outcome between the two study groups. Over the period of two years there was no significant difference between the head survival rate between both groups. In contrast to that, we could not perceive any significant change in the volume of FHN in both treatment groups related to the longitudinal course after treating. The number of CFU showed a significant increase after centrifugation. This trial could not detect a benefit from the additional injection of bone marrow concentrate with regard to bone regeneration and clinical outcome in the short term.

Cavovarus deformity in Charcot-Marie-Tooth disease: is there a hindfoot equinus deformity that needs treatment?

Background

Charcot-Marie-Tooth disease (CMT), one of the most common hereditary neurologic disorders, often results in debilitating cavovarus foot deformities. The deformities are still not fully understood, and the treatment recommendations are consequently heterogeneous, often including calf muscle or Achilles tendon lengthening.

Methods

We examined 40 patients (80 feet) with CMT and bilateral cavovarus deformities (19 men and 21 women, mean age 33.6 ± 14.6 years) and the feet of a healthy control population of 13 individuals (7 men and 6 women, mean age 43.9 ± 10.8 years). In all cases 3D instrumented gait analysis results with both conventional Plug-in-Gait analysis and the Heidelberg Foot Measurement Method (HFMM) were used to determine the sagittal plane kinematics, dorsi-plantar flexion (DPF), tibio-talar dorsiflexion (TTDF), and medial arch angle (MAA), and the results of patients and the control group were compared using the 2 methods. Decreased and increased dorsiflexion using TTDF was defined as 1 standard deviation below or above the mean of the control. Comparisons were done using descriptive statistics, the Pearson correlation coefficient and ANOVA.

Results

The TTDF was found to be decreased in 18 of the 80 feet examined (22.5 %), normal in 31 feet (38.75 %), and increased in 31 feet (38.75 %). The Pearson coefficient showed a positive correlation with R = 0.765, p < 0.001 between decreased TTDF values found by HFMM and decreased DPF values found with conventional Plug-in-Gait analysis, but a very weak correlation in patients with normal TTDF (R = -0.118) and increased TTDF (R = 0.078). Also, in patients with decreased TTDF values, there was a weak to moderate correlation with the MAA (R = 0.335), but no correlation between the MAA and DPF (R = 0.023).

Conclusions

The HFMM, unlike the conventional Plug-in-Gait analysis, distinguishes between the segments of the foot in foot deformities and facilitates evaluation of the hindfoot equinus component in patients with CMT and cavovarus deformity. Although there is a significant correlation between decreased TTDF with HFMM and decreased DPF with conventional Plug-in-Gait analysis, this correlation was not seen in patients with normal or increased TTDF values. Conventional Plug-in-Gait analysis alone does not indicate if an increased plantar flexion deformity is the result of either a cavus deformity or hindfoot equinus deformity, which limits its usefulness in assisting in treatment decision making.

Significantly worse isokinetic hamstring-quadriceps ratio in patellofemoral compared to condylar defects 4 years after autologous chondrocyte implantation

PURPOSE

Detailed biomechanical analysis including isokinetic muscle strength measurements after autologous chondrocyte implantation (ACI) are still rare, but might be of crucial importance for long-term outcomes. The present prospective study was performed to evaluate whether defect location had any influence on clinical and biomechanical outcomes 4 years after ACI.

METHODS

Forty-four patients with full-thickness cartilage defects ICRS grade III B and C underwent ACI and were assigned to two groups, the femoral condyle group or the patellofemoral joint group. Clinical scores were gathered preoperatively and 6, 12 and 48 months after implantation using the International Knee Documentation Committee (IKDC) score and the International Cartilage Repair Society (ICRS) form. Isokinetic strength measurements were performed 48 months postoperatively comparing healthy and operated knee joint of each patient.

RESULTS

Clinical scores (ICRS, IKDC) showed continuous significant (p < 0.05) improvement over the study period for both groups. Isokinetic muscle strength measurements showed significantly reduced maximum strength capacities for the operated knee joint compared to the healthy knee in both groups (p < 0.05). Hamstring-quadriceps ratios of the operated extremity revealed a significant change in physiological muscle balancing (ratios >1.0) based on significantly impaired extensor muscle strength in the patellofemoral joint group.

CONCLUSION

All patients showed significant strength deficits on the operated extremity 4 years after ACI. Furthermore, the patellofemoral compartment in particular showed significantly worse hamstring-quadriceps ratios compared to condylar defects. Consequently, more efforts should be made to restore muscular strength especially of the quadriceps and the rehabilitation protocol should be adjusted accordingly.

LEVEL OF EVIDENCE

II.

Surgical Treatment of Severe Cavovarus Foot Deformity in Charcot-Marie-Tooth Disease

Introduction

A successful adjusted treatment algorithm for the correction of cavovarus foot deformity requires soft-tissue balancing procedures, in particular total split posterior tibial tendon transfer (T-SPOTT), in combination with adjunctive corrective procedures depending on the degree of deformity.

Step 1: Surgical Preparation

Place the patient in a supine position and follow a standard aseptic surgical disinfection and draping protocol, allowing access to the iliac crest.

Step 2: Steindler Release of the Plantar Aponeurosis

Use a medial approach to access and transect the plantar aponeurosis.

Step 3: Release the Posterior Tibial Tendon at the Foot

Transect the posterior tibial tendon near its insertion point.

Step 4: Retract and Split the Posterior Tibial Tendon at the Calf and Transfer It Through the Interosseous Membrane

Make a medial incision in the distal part of the calf, retract the posterior tibial tendon (and flexor digitorum tendon if necessary), split it longitudinally in half, and pass it through the interosseous space.

Step 5: Reveal the Target Tendons and Pull the Posterior-Tibial-Tendon Halves to These Tendons

Expose the anterior tibial and peroneal tendons and pull the posterior-tibial-tendon halves (and flexor digitorum longus tendon of it is being used) to these tendons.

Step 6: Chopart, or Triple or Lambrinudi, Arthrodesis

Perform a Chopart, or triple or Lambrinudi¹⁶, arthrodesis when osseous correction and stabilization are required for fixed deformities.

Step 7: Modified Jones Procedure

If the cavovarus foot displays flexible clawing of the big toe, carry out a modified Jones procedure.

Step 8: Extension Osteotomy of the First Metatarsal

If the first metatarsal remains in a fixed plantar flexed position and cannot be corrected with the Jones procedure, perform a dorsal-based wedge extension osteotomy.

Step 9: Clawing of the Lesser Toes

Incise the plantar tendons, transect the long flexor tendons, and place a single Hohmann wire through the end of each claw toe.

Step 10: Soft-Tissue Equinus Correction (Rarely Needed)

Depending on the severity of the remaining equinus, correct it with calf muscle or calcaneal tendon lengthening (the more severe the equinus, the more distal the corrective measure).

Step 11: Supramalleolar Varus Derotation Osteotomy

If foot external rotation is increased after foot correction, supramalleolar derotation osteotomy should be added to avoid lever-arm problems postoperatively.

Step 12: Complete the Tendon Transfers

Attach the transferred tendons to their respective target tendons using a Pulvertaft needle with a Pulvertaft weave technique, while keeping the foot in a plantigrade position.

Step 13: Wound Closure

Reevaluate the foot and determine if all corrections have been made, perform necessary final radiographic documentation, release the tourniquet, perform hemostasis, clean the wounds, and close them.

Step 14: Postoperative Management and Aftercare

The achieved operative correction is only as good as the postoperative treatment allows.

Results

Various authors have recommended posterior tibial tendon transfer to the dorsum of the foot to correct foot drop.

Indications

Contraindications

Pitfalls & Challenges

Treatment of severe bone defects during revision total knee arthroplasty with structural allografts and porous metal cones-a systematic review

Aseptic loosening and focal osteolysis are the most common reasons for knee arthroplasty failure. The best treatment remains unclear. We reviewed the literature on the treatment of revision knee arthroplasty using bony structural allografts (476 cases) and porous metal cones (223 cases) to determine if a difference in the revision failure rates was discernable. The failure rates were compared using a logistic regression model with adjustment for discrepancies in FU time and number of grafts used (femoral, tibial, or both). In this analysis, the porous implant shows a significantly decreased loosening rate in AORI 2 and 3 defects. The overall failure rate was also substantially lower in the porous metal group than the structural allograft group; little difference in the infection rates was noted.

Bone quality assessment for total hip arthroplasty with intraoperative trabecular torque measurements

Background

In cases of poor bone quality, intraoperative torque measurement might be an alternative to preoperative dual-energy X-ray absorptiometry (DXA) to assess bone quality in total hip arthroplasty (THA).

Methods

Trabecular peak torque measurement was applied in 14 paired fresh frozen human femurs. Here, a 6.5 × 23 mm wingblade was inserted into the proximal femur without harming the lateral cortical bone. Further tests of the proximal femur also evaluated bone strength (DXA, micro-computed tomography (μCT), monoaxial compression test), and the results were compared to the trabecular torque measurement. Student’s t-test was used to compare the values of the groups. Pearson product–moment was applied to correlate the values of the peak torque measurement with the bone strength measured by DXA, μCT, and monoaxial compression test.

Results

In the femoral head, the mean trabecular peak torque was 4.38 ± 1.86 Nm. These values showed a strong correlation with the values of the DXA, the μCT, and the biomechanical load test (Pearson’s product–moment: DXA: 0.86, μCT-BMD: 0.80, load test: 0.85). Furthermore, the torque measurement showed a more pronounced correlation with the biomechanical load test compared to the DXA.

Conclusions

The use of this method provides highly diagnostic information about bone quality. Since the approach was adjusted for THA, no harm of the lateral bone stock will result from this measurement during surgery. The results of this initial study employing small sample sizes indicate that this new method is as sensitive as DXA in predicting bone quality and may function as an intraoperative alternative to DXA in THA. Nevertheless, before this method will turn into clinical use, more research and clinical trials are necessary.

The stability of the femoral component in the Oxford unicompartmental knee replacement: a comparison of single and twin peg designs

Aseptic loosening of the femoral component is an important indication for revision surgery in unicompartmental knee replacement (UKR). A new design of femoral component with an additional peg was introduced for the cemented Oxford UKR to increase its stability. The purpose of this study was to compare the primary stability of the two designs of component. Medial Oxford UKR was performed in 12 pairs of human cadaver knees. In each pair, one knee received the single peg and one received the twin peg design. Three dimensional micromotion and subsidence of the component in relation to the bone was measured under cyclical loading at flexion of 40° and 70° using an optical measuring system. Wilcoxon matched pairs signed-rank test was performed to detect differences between the two groups. There was no significant difference in the relative micromotion (p = 0.791 and 0.380, respectively) and subsidence (p = 0.301 and 0.176, respectively) of the component between the two groups at both angles of flexion. Both designs of component offered good strength of fixation in this cadaver study.

Mechanical properties of a cemented porous implant interface

BACKGROUND

Revision arthroplasty often requires anchoring of prostheses to poor-quality or deficient bone stock. Recently, newer porous materials have been introduced onto the market as additional, and perhaps better, treatment options for revision arthroplasty. To date, there is no information on how these porous metals interface with bone cement. This is of clinical importance, since these components may require cementing to other prosthesis components and occasionally to bone.

METHODS

We created porous metal and bone cylinders of the same size and geometry and cemented them in a well-established standardized setting. These were then placed under tensile loading and torsional loading until failure was achieved. This permitted comparison of the porous metal/cement interface (group A) with the well-studied bone/cement interface (group B).

RESULTS

The group A interface was statistically significantly stronger than the group B interface, despite having significantly reduced depth of cement penetration: it showed a larger maximum tensile force (effect size 2.7), superior maximum tensile strength (effect size 2.6), greater maximum torsional force (effect size 2.2), and higher rotational stiffness (effect size 1.5).

INTERPRETATION

The newer porous implants showed good interface properties when cemented using medium-viscosity bone cement. The axial and rotational mechanical strength of a porous metal/cement interface appeared to be greater than the strength of the standard bone/cement interface. These results indicate that cementing of porous implants can provide great stability in situations where it is needed.

Hip reconstruction surgery is successful in restoring joint congruity in patients with cerebral palsy: long-term outcome

PURPOSE

Neurogenic hip dislocation is frequently observed in patients with cerebral palsy (CP). If the hip is not centred but not dislocated, the hip joint can be recentered with minor operative effort. Reconstructive procedures are indicated if the femoral head is subluxated or dislocated. There are no data as to when destruction of the femoral head requires a salvage procedure or whether hip reconstruction surgery is successful in restoring joint congruity in patients with CP. Our aim was to investigate femoral head plasticity after hip reconstruction surgery in a long-term outcome study.

METHODS

We studied a large cohort of patients with CP and high hip dislocation (Tönnis grade IV) before surgery. Sixty-eight patients were assessed, of whom 23 presented with bilateral high hip dislocation, and 91 complex hip reconstructions were conducted. Standardised radiographic examination was performed before and directly after surgery and at the long-term follow-up examination.

RESULTS

Pain was the most frequent reason for complex hip-joint reconstruction (49 patients, 72%). An impressive improvement in pain was demonstrated postoperatively. Forty-five hip joints presented aspheric incongruity postoperatively, which improved on average 7.7 years after surgery and 59 hip joints showed congruency. Only 15% of patients experienced pain at the time of final follow-up, and that was of low intensity.

CONCLUSIONS

Early conservative treatment for hip dislocation is helpful, and operative reconstruction should also be scheduled early. Continued surveillance is necessary, and Reimers index is useful for monitoring the development of hip centering. In case of hip pain and femoral head deformity, our long-term study indicates that hip reconstruction surgery as a part of multilevel surgery improves pain and function in patients with CP and Tönnis IV hip dislocation, even if the hip joint is incongruent after operation. This incongruity improves over the long-term. If possible, a reconstruction procedure should be performed before the femoral head becomes deformed. High plasticity of the hip joint suggest that even if the femoral head is deformed, hip reconstruction can be recommended.

Loosening after acetabular revision: comparison of trabecular metal and reinforcement rings. A systematic review

The best method of revision acetabular arthroplasty remains unclear. Consequently, we reviewed the literature on the treatment of revision acetabular arthroplasty using revision rings (1541 cases; mean follow-up (FU) 5.7 years) and Trabecular Metal, or TM, implants (1959 cases; mean FU 3.7 years) to determine if a difference with regard to revision failure could be determined. Failure rates of the respective implants were compared statistically using a logistic regression model with adjustment for discrepancies in FU time. In our study, TM shows statistically significant decreased loosening rates relative to revision rings for all grades including severe acetabular defects and pelvic discontinuity. The severe defects appear to benefit the most from TM.

Treatment of periprosthetic femoral fractures with two different minimal invasive angle-stable plates: Biomechanical comparison studies on cadaveric bones

INTRODUCTION

The introduction of fixed-angle plate osteosynthesis techniques has provided us a further means to treat periprosthetic femoral fractures. The goal of this experimental study is to evaluate the biomechanical properties and stability of treated periprosthetic fractures when using two different plate systems, which vary in the locking mechanism and the screw placement (monocortical or bicortical) with respect to the prosthesis stem.

MATERIALS AND METHODS

Using five pairs of formalin-fixed femora, a Vancouver B1 periprosthetic fracture was treated either with a 13-hole LISS(®) titanium plate using four monocortical periprosthetic screws or with a non-contact bridging plate (NCB) DF(®) plate using bicortical angle-stable blocked screws positioned ventrally or dorsally to the prosthesis stem. Bones were loaded under axial and cyclic compression with a progressively increased load until failure. Displacement at the osteotomy gap was measured during loading using an ultra-sound measuring system.

RESULTS

The mean displacement in the region of the fracture gap was not significantly different at any time during the experiments for the two models. The mean force resulting in subsequent model failure was similar in both models; the failure morphology varied slightly between the models, however. Four of the five LISS(®) models exhibited either a tear-out of the monocortical screws or a decortication from the bony shaft of the cortical lamella surrounding the screws. On the other side, two of the NCB models showed macroscopically visible fissures along the osteosynthesis plates at the height of the osteotomy gap, and were hence considered implant failures. Only one NCB model showed tear-out of the bicortically placed screws.

CONCLUSION

Bicortical screw placement provides more stable anchoring when compared to monocortical screw fixation. However, in relation to the amount of motion at the osteotomy gap and to failure loads, stabilisation of periprosthetic femoral fractures can be equally well achieved using either the LISS(®) plate with periprosthetic monocortical screws or the NCB plate with poly-axially placed bicortical screws.

Perioperative Management to Improve Neurologic Outcome in Thoracic or Thoracoabdominal Aortic Stent-Grafting

BACKGROUND

Thoracic or thoracoabdominal aortic stent-graft repair has shown a reduction in morbidity and mortality rates due to the procedure's advantages (no aortic cross-clamping, continuous distal aortic perfusion, no reperfusion injury). However, 3% to 12% of the patients are at risk of spinal cord ischemia. We investigated spinal cord protective measures with evoked potentials, cerebrospinal fluid drainage, and prevention of hypotension to minimize postoperative neurologic deficit.

METHODS

Between November 2000 and July 2005, vital parameters and spinal cord function were monitored, including cerebrospinal fluid pressure and transcranial motor-evoked and somatosensory-evoked potentials in 36 stent-graft procedures (31 patients) on the thoracic or thoracoabdominal aorta.

RESULTS

Stent-graft placement was technically successful in all patients. We achieved a survival rate of 100% without neurologic deficit after fast-track extubation. Eleven of 31 patients exhibited changes in evoked potentials during stent-graft deployment. In 12 of 31 patients (including the 11 with evoked potential alterations), cerebrospinal fluid pressure exceeded 15 mm Hg. Cerebrospinal fluid drainage and vital parameter adjustment were executed in those instances. We observed intraoperative evoked potential total recovery in 10 of 11 patients after these interventions.

CONCLUSIONS

Interventions to improve spinal cord perfusion led to total recovery of spinal function in most patients (10/11). Therefore, spinal cord protective measures with motor- and somatosensory-evoked potential monitoring, cerebrospinal fluid drainage, and prevention of hypotension can reduce the incidence of spinal cord ischemia and improve the neurologic outcome of patients undergoing endovascular thoracic or thoracoabdominal aortic repair.