The lexicon for periprosthetic bone loss versus osteolysis after cervical disc arthroplasty: a systematic review.

BACKGROUND: Periprosthetic bone loss is a common observation following arthroplasty. Recognizing and understanding the nature of bone loss is vital as it determines the subsequent performance of the device and the overall outcome. Despite its significance, the term "bone loss" is often misused to describe inflammatory osteolysis, a complication with vastly different clinical outcomes and treatment plans. Therefore, the goal of this review was to report major findings related to vertebral radiographic bone changes around cervical disc replacements, mitigate discrepancies in clinical reports by introducing uniform terminology to the field, and establish a precedence that can be used to identify the important nuances between these distinct complications. METHODS: A systematic review of the literature was conducted following PRISMA guidelines, using the keywords "cervical," "disc replacement," "osteolysis," "bone loss," "radiograph," and "complications." A total of 23 articles met the inclusion criteria with the majority being retrospective or case reports. RESULTS: Fourteen studies reported periprosthetic osteolysis in a total of 46 patients with onset ranging from 15-96 months after the index procedure. Reported causes included: metal hypersensitivity, infection, mechanical failure, and wear debris. Osteolysis was generally progressive and led to reoperation. Nine articles reported non-inflammatory bone loss in 527 patients (52.5%), typically within 3-6 months following implantation. The reported causes included: micromotion, stress shielding, and interrupted blood supply. With one exception, bone loss was reported to be non-progressive and had no effect on clinical outcome measures. CONCLUSIONS: Non-progressive, early onset bone loss is a common finding after CDA and typically does not affect the reported short-term pain scores or lead to early revision. By contrast, osteolysis was less common, presenting more than a year post-operative and often accompanied by additional complications, leading to revision surgery. A greater understanding of the clinical significance is limited by the lack of long-term studies, inconsistent terminology, and infrequent use of histology and explant analyses. Uniform reporting and adoption of consistent terminology can mitigate some of these limitations. Executing these actionable items is critical to assess device performance and the risk of revision. LEVEL OF EVIDENCE IV: Diagnostic: individual cross-sectional studies with consistently applied reference standard and blinding.

Cross-Sectional Areas and Volumes Occupied by Implants in Simulated Scaphoid Fractures.

PURPOSE: This study determined the volume of bone replaced by an implant at the proximal and distal poles of simulated scaphoid fractures. We also measured the cross-sectional area of the implant relative to the cross-sectional area of the scaphoid at 2 different simulated fracture locations. METHODS: Microcomputed tomograhy scans of 7 cadaveric scaphoids were used to create 3-dimensional models in which transverse proximal pole and midwaist fractures were simulated. The volume occupied by 5 commonly used implants and the cross-sectional area occupied at the surface of the fractures was measured using a computer modeling software. RESULTS: For simulated proximal pole fractures, the implants replaced 1.5%-7.4% of the fracture cross-sectional area and 1.2%-6.4% of the proximal fragment bone volume. For midwaist fractures, the implants replaced 1.5%-6.8% of the fracture cross-sectional area and 1.8%-4.6% of the proximal pole volume. Although the different implant designs replaced different areas and volumes, all these differences were small and below 4%. CONCLUSIONS: This study provides data that relate to one aspect of fracture healing, specifically, the surface area occupied by 5 different implants in proximal and midwaist scaphoid fractures as well as the volume of bone replaced by the implant. CLINICAL RELEVANCE: As opposed to the impression provided by 2-dimensional planar imaging, when studied using a 3-dimensional model, the volume and surface area replaced by an implant represent a minimal percentage of scaphoid bone, suggesting a negligible clinical effect.

Quantification of Ankle Dorsiflexion in Ponseti-managed Unilateral Clubfoot Patients During Early Childhood.

BACKGROUND: Following the initial correction of a clubfoot using the Ponseti method, diminished passive ankle dorsiflexion may be observed over time, which could represent a possible relapsed deformity. Alternatively, the change may be attributable to patient age or other variables. Our purpose was to quantify passive ankle dorsiflexion in the involved and contralateral unaffected limbs of Ponseti-managed unilateral clubfoot patients, and to determine what patient-related variables influence this finding. METHODS: In total, 132 unilateral clubfoot patients were studied. Passive ankle dorsiflexion was measured in both limbs at each visit. Data were excluded from visits in which patients showed clear evidence of a relapse. Mean ankle dorsiflexion for clubfeet and contralateral unaffected limbs were reported for annual age intervals and compared using paired t tests. A general linear model was established to assess the effects of age, severity, sex, and side on ankle dorsiflexion. RESULTS: Mean ankle dorsiflexion for unaffected limbs declined with age, measuring 53±6 degrees between 0 and 1 year of age and decreasing to 39±7 degrees by 4 to 5 years of age. Similarly, mean ankle dorsiflexion in treated clubfeet declined with age, measuring 44±7 degrees between 0 and 1 year and 29±7 degrees between 4 and 5 years. Overall, the difference between limbs in these patients averaged ~10 degrees for every age interval through 9 years (P<0.001). Ankle dorsiflexion of clubfeet in 95% of patients aged 0 to 2 years was at least 20 degrees, and in 95% of patients aged 3 to 5 years this was at least 15 degrees. Patient age (P<0.001) and severity of deformity (P<0.001) were found to be the only significant factors affecting ankle dorsiflexion in the affected limbs. CONCLUSIONS: Ankle dorsiflexion in the Ponseti-treated clubfeet was influenced by age of the patient and the initial severity of the affected limb. Furthermore, our data suggest that, in patients who showed no relapse, a minimum of 20 degrees of ankle dorsiflexion in the corrected clubfoot is maintained through age 3 years and a minimum of 15 degrees is maintained through age 5 years. LEVEL OF EVIDENCE: Level IV-this is a retrospective case series.

Damage patterns in polyethylene fixed bearings of retrieved total ankle replacements.

INTRODUCTION: Poor long-term outcomes continue to hinder the universal adoption of total ankle replacements (TAR) for end stage arthritis. In the present study, polyethylene inserts of TARs retrieved at revision surgery were analyzed for burnishing, scratching, mechanical damage, pitting, and embedded particles. METHODS: Fourteen retrieved polyethylene inserts from a fixed bearing total ankle replacement design currently in clinical use were analyzed. Duration of time in vivo was between 11.5 months and 120.1 months. Three investigators independently graded each articular surface in quadrants for five features of damage: burnishing, scratching, mechanical damage, pitting, and embedded particles. RESULTS: No correlation was found for burnishing between the anterior and posterior aspects (p = 0.47); however, scratching and pitting were significantly higher on the posterior aspect compared to the anterior aspect (p < 0.03). There was a high correlation between burnishing and in vivo duration of the implant (anterior: R = 0.67, p = 0.01, posterior: R = 0.68, p = 0.01). CONCLUSION: The higher concentration of posterior damage on these polyethylene inserts suggested that prosthesis-related (design) or surgeon-related (technique) factors might restrict the articulation of the implant. The resulting higher stresses in the posterior articular surfaces may have contributed to the failure of retrieved implants Keywords: Retrieval, Polyethylene Damage, Total Ankle Replacement.

Sagittal Plane Residual Deformity in Pediatric Type II Supracondylar Humerus Fractures.

INTRODUCTION: The incidence of residual deformity in the sagittal plane of the humerus (RDSPH) after nonoperative management of type II supracondylar humerus fractures (SCHFs), and the effects of such deformity on the overall arc of motion (AOM) of the elbow, are unknown. Our purpose was to analyze data collected prospectively on a large cohort of type II SCHF's to establish the incidence and extent of RDSPH, and the effects of the deformity on the elbow function, to further support our previously published recommendations on the treatment of type II SCHF. METHODS: The clinical data and radiographs of 1107 pediatric type II SCHFs enrolled in a prospective registry, and followed for a minimum of 8 weeks, were retrospectively reviewed. The radiographs obtained during the latest follow-up appointment were examined for the presence of RDSPH, as demonstrated by the anterior humeral line falling anterior or posterior relative to the center of the capitellum. The amount of RDSPH in the sagittal plane was then calculated. We compared the treatment outcome of elbows with and without RDSPH by assessing the patients' AOM, the arc of flexion (AOF), and relative arcs of motion (R-AOM) and relative arcs of flexion (R-AOF) (as compared with the unaffected, contralateral elbow). RESULTS: Overall, 799 (72.2%) fractures were treated nonsurgically, and 308 (27.8%) fractures were treated surgically. The overall incidence of RDSPH was 10.2%. None of the fractures managed operatively demonstrated residual deformity. The RDSPH was classified as mild in 35 fractures (3.2%), moderate in 64 fractures (5.7%) and severe in 14 fractures (1.3%). Therefore, the incidence of RDSPH in fractures treated nonoperatively was 14.1%. In fractures treated nonoperatively, the difference in AOM between those without (n=686) and with (n=113) RDSPH was <4 degrees (149.1 vs. 145.8 degrees, P=0.02). Those with and without RDSPH had a clinically similar AOF, with a mean difference of<4 degrees (134.5 vs. 137.9 degrees, P<0.0001). The differences in R-AOM and R-AOF between those with and without RDSPH were minimal (97.3% vs. 95.6% and 96.6% vs. 95.3%, respectively). A satisfactory outcome, defined as an R-AOM of at least 85% when compared with the unaffected, contralateral side at the latest follow-up, was achieved in 91% of fractures with RDSPH, and 93% of fractures without RDSPH. DISCUSSION AND CONCLUSION: The incidence of RDSPH in type II SCHF treated nonoperatively was 14%. In our cohort, nearly 99% of all RDSPH were mild to moderate. On the basis of the data presented in the current study, nonsurgical treatment of type II SCHF can provide a satisfactory recovery of AOM, AOF, R-AOM, and R-AOF, and a high rate of satisfactory outcomes, even in the presence of RDSPH.

Preclinical biomechanical testing models for the tibiotalar joint and its replacements: A systematic review.

In recent years, total ankle replacements have gained increasing popularity as an alternative to fusion. Preclinical testing of TARs requires reliable in vitro models which, in turn, need thorough knowledge of the kinematics of the tibiotalar joint. Surprisingly few studies have been published to simulate the in vivo kinematics of the tibiotalar joint. Among these studies, there is a wide range of methods and magnitudes of applied loads. The purpose of the present review was to summarize the applied loads, positions that were tested during static simulations, and ranges of motion simulated that have been used in human cadaveric models of the tibiotalar joint. Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, PubMed and Google Scholar were searched for studies pertaining to cadaveric tibiotalar joint kinematics. Our search yielded 12 appropriate articles that were included in the systematic review. While it is well known that loads at the tibiotalar joint are frequently as high as 5 times bodyweight [1], these studies reported applied loads varying from 200N-750N, below average bodyweight. Three studies used dynamic loading of custom apparatuses to drive cadaver limbs along predetermined paths to simulate gait. Conversely, the other nine studies applied static loads (∼300N), performed at discreet points during the stance phase, considerably lower than physiological conditions. The present systematic review calls for an urgent need to establish a consensus for preclinical evaluation of TARs for biomechanical function.

Defining a Safe Zone for All-Inside Lateral Meniscal Repairs in Pediatric Patients: A Magnetic Resonance Imaging Study.

PURPOSE: To establish a safe zone for all-inside meniscal fixation in pediatric patients by use of magnetic resonance imaging (MRI) measurements between the popliteal tendon (PT) and popliteal neurovascular bundle (PNVB). METHODS: Patients aged 5 to 16 years with normal or nearly normal knee MRI scans were included. They were grouped by age: group I, 5 to 7 years (n = 61); group II, 8 to 10 years (n = 59); group III, 11 to 13 years (n = 60); and group IV, 14 to 16 years (n = 70). At the level of the lateral meniscus, 2 lines starting at the lateral patellar tendon border and ending at the medial edge of the PT (D1) and the lateral edge of the PNVB (D2) were made on an axial knee MRI scan. A third line (D3) connected D1 to D2 at the meniscocapsular junction of the posterior horn of the lateral meniscus (PHLM). A fourth line (D4), derived geometrically, was parallel and 8 mm anterior to D3, simulating the anterior edge of the PHLM. RESULTS: Axial MRI scans of 250 pediatric patients (aged 5-16 years) were retrospectively reviewed. Analysis showed significant correlation between age and sex for D3 (P < .0001). For D3, there were significant differences among all age groups, except between groups III and IV. The average D3 by age group was 14.1 mm (standard deviation [SD], 3.1 mm) for group I, 15.8 mm (SD, 2.5 mm) for group II, 17.0 mm (SD, 3.3 mm) for group III, and 17.2 mm (SD, 3.1 mm) for group IV. The average D4 was 11.39 mm (SD, 2.6 mm), 13.24 mm (SD, 2.24 mm), 14.59 mm (SD, 2.89 mm), and 14.80 mm (SD, 2.79 mm), respectively. There were significant differences in D3 and D4 in male versus female patients (17.6 mm vs 15.7 mm, P < .001, and 14.9 mm vs 13.2 mm, P < .001, respectively), particularly in groups III and IV (17.0 mm vs 13.8 mm and 16.8 mm vs 13.9 mm, respectively). CONCLUSIONS: This study provides normative data of the distance between the PNVB and PT at the meniscocapsular junction (D3) and anterior edge of the PHLM (D4) with the knee in full extension. Combined with previous studies showing that the addition of knee flexion increases the distance between the meniscus and the neurovascular bundle, these data can be used by surgeons to improve the safety of PHLM repair in pediatric patients. LEVEL OF EVIDENCE: Level III, diagnostic study of nonconsecutive patients.

Is the "Appropriate Use Criteria" for Type II Supracondylar Humerus Fractures Really Appropriate?

INTRODUCTION: The Appropriate Use Criteria for the treatment of supracondylar humerus fractures (SCHFs), developed by American Academy of Orthopaedic Surgeons, recommends pinning for all type II SCHFs. However, previous studies have suggested that, with close follow-up some of the less severe type II SCHF's can be successfully treated without surgery. Our purpose was to analyze data collected prospectively on a large cohort of type II SCHF's. METHODS: We reviewed clinical and radiographic information on all type II pediatric SCHF (n=1120) that were enrolled in a prospective registry and were followed for a minimum of 8 weeks. The characteristics of the patients who were treated without surgery were compared with those of patients who were ultimately treated surgically. Treatment outcomes, as assessed by the final clinical and radiographic alignment, range of motion of the elbow, and complications were compared between the groups to define clinical and radiographic features that related to success or failure of nonoperative management. RESULTS: Ultimately, 812 fractures (72%) were treated nonoperatively, and 309 fractures (28%) were treated surgically. At final follow-up, outcome measures of change in carrying angle, range of motion, and complications did not show clinically significant differences between treatment groups. Binary logistic regression analysis indicated that initial radiographic features, specifically rotational deformity, varus malalignment, valgus malalignment, and a shaft-condylar angle of <30 degrees were strongly related to selection for surgery. Patients with isolated extension deformity, but none of the other features, were more likely to complete successful nonoperative management. CONCLUSIONS: Pinning all type II SCHF, as recommended by the Appropriate Use Criteria, would have resulted in unnecessary surgery in 72% of patients in this series. Given the wide range of injury severity within the type II category of SCHF, better discrimination of factors commonly associated with successful nonoperative treatment is required. In this particular series, fractures with an isolated extension deformity (without rotational or coronal malalignment) were more likely to complete successful nonoperative management.

Biomechanical comparison of fixation stability using a Lisfranc plate versus transarticular screws.

BACKGROUND: To obtain adequate fixation in treating Lisfranc soft tissue injuries, the joint is commonly stabilized using multiple transarticular screws; however iatrogenic injury is a concern. Alternatively, two parallel, longitudinally placed plates, can be used to stabilize the 1st and 2nd tarsometatarsal joints; however this may not provide adequate stability along the Lisfranc ligament. Several biomechanical studies have compared earlier methods of fixation using plates to the standard transarticular screw fixation method, highlighting the potential issue of transverse stability using plates. A novel dorsal plate is introduced, intended to provide transverse and longitudinal stability, without injury to the articular cartilage. METHODS: A biomechanical cadaver model was developed to compare the fixation stability of a novel Lisfranc plate to that of traditional fixation, using transarticular screws. Thirteen pairs of cadaveric specimens were tested intact, after a simulated Lisfranc injury, and then following implant fixation, using one method of fixation randomly assigned, on either side of each pair. Optical motion tracking was used to measure the motion between each of the following four bones: 1st metatarsal, 2nd metatarsal, 1st cuneiform, and 2nd cuneiform. Testing included both cyclic abduction loading and cyclic axial loading. RESULTS: Both the Lisfranc plate and screw fixation method provided stability such that the average 3D motions across the Lisfranc joint (between 2nd metatarsal and 1st cuneiform), were between 0.2 and 0.4mm under cyclic abduction loading, and between 0.4 and 0.5mm under cyclic axial loading. Comparing the stability of fixation between the Lisfranc plate and the screws, the differences in motion were all 0.3mm or lower, with no clinically significant differences (p>0.16). CONCLUSIONS: Diastasis at the Lisfranc joint following fixation with a novel plate or transarticular screw fixation were comparable. Therefore, the Lisfranc plate may provide adequate support without risk of iatrogenic injury to the articular cartilage.

Five Hundred Fifty-five Retrieved Metal-on-metal Hip Replacements of a Single Design Show a Wide Range of Wear, Surface Features, and Histopathologic Reactions.

BACKGROUND: In 2010, a widely used metal-on-metal hip implant design was voluntarily recalled by the manufacturer because of higher than anticipated failure rates at 5 years. Although there was a large published range of revision rates, numerous studies had reported a higher risk of revision for excessive wear and associated adverse tissue reactions when compared with other metal-on-metal total hips. The reasons for this were suggested by some to be related to cup design features. QUESTIONS/PURPOSES: From retrievals of ASR metal-on-metal implants and tissue samples obtained at revision surgery, we asked the following questions: (1) What were the common and uncommon surface features? (2) What were the common and uncommon linear and volumetric wear characteristics? (3) Were there common taper corrosion characteristics? (4) What aseptic lymphocytic vasculitis-associated lesion (ALVAL) features were present in the tissues? METHODS: Five hundred fifty-five ASRs, including 23 resurfacings, were studied at one academic research center. Features of wear (eg, light and moderate scratching), damage (eg, deposits, gouges), and bone attachment on the porous coating were semiquantitatively ranked from 0 (none) to 3 (> 75%) based on the amount of a feature in each region of interest by the same experienced observer throughout the study. Visible features of head taper corrosion were ranked (Goldberg score) from 1 (none) to 4 (severe) by the same observer using a previously published scoring method. An experienced tribologist measured component wear depth using a coordinate measuring machine and quantified wear volume using previously validated methods. All available tissues were sampled and examined for features of ALVAL and scored from 0 to 10 by a single observer using a method they previously developed and published. A score from 0 to 4 is considered low, 5 to 8 is considered moderate, and 9 or 10 is considered high with regard to the risk of metal hypersensitivity features in the tissues. RESULTS: The most common bearing surface features were light and moderate scratches and removal or postremoval damage. Discoloration and deposits were commonly observed on femoral heads (55% [305 of 553]) and less commonly on cups (30% [165 of 546]). There was no evidence of impingement or dislocation damage. There was typically a small amount of bone attachment in at least one of eight designated regions of interest (84% [460 of 546]); extensive or no bone attachment was uncommon. Edge wear was highly prevalent. The maximum wear of 469 cups (88%) occurred near the edge, whereas the maximum wear of 508 femoral heads (94%) occurred between the pole and 45° from the pole. The median combined head-cup wear volume was 14 mm (range, 1-636 mm). One hundred sixty-nine pairs (32%) had a combined wear volume of < 10 mm, 42 pairs (8%) had volumetric wear of > 100 mm, and 319 pairs (60%) had wear volume between 10 and 100 mm³. Seventy-four percent of tapers (390 of 530) received a Goldberg score of 4, 22% (116 of 530) a score of 3, < 5% (24 of 530) a score of 2, and none received a score of 1. The most frequent ALVAL score was 5 out of 10 (35 of 144 hips [24%]) and ranged from 2 (one hip) to 10 (nine hips); 92 of 144 (64%) had a moderate score, 17 of 144 (12%) had a high score, and 35 (24%) had a low score. CONCLUSIONS: Although edge wear was prevalent, in most cases, this was not associated with high wear. The increased diameter and decreased coverage angle of the ASR design may have resulted in the observed high incidence of edge wear while perhaps decreasing the risk for impingement and dislocation. CLINICAL RELEVANCE: The role of bearing wear in the revisions of metal-on-metal implants is controversial, because it is known that there is a large range of in vivo wear rates even within the same implant type and that patient variability affects local tissue responses to wear debris. The observations from our study of 555 retrieved ASR implant sets indicate that there was a wide range of wear including a subset with very high wear. The results suggested that the failure of the ASR and ASR XL was multifactorial, and the failure of different subgroups such as those with low wear may be the result of mechanisms other than reaction to wear debris.

A Removable Long-arm Soft Cast to Treat Nondisplaced Pediatric Elbow Fractures: A Randomized, Controlled Trial.

BACKGROUND: The ideal type of immobilization for nondisplaced pediatric elbow fractures has not been established. We hypothesized that the use of a long-arm cylinder made of soft cast material will result in similar outcomes to those obtained with a traditional long-arm hard cast. METHODS: We randomly assigned 100 consecutive children who presented with a closed, nondisplaced, type I supracondylar humeral fracture or an occult, closed, acute elbow injury, to 1 of 2 groups: group A (n=50) received a long-arm, traditional fiberglass (hard) cast. Group B (n=50) received a long-arm, soft fiberglass cast. After 4 weeks, the cast was removed in group A by a member of our staff using a cast saw, and in group B by one of the patient's parents by rolling back the soft fiberglass material. We compared the amount of fracture displacement and/or angulation, recovery of range of motion, elbow pain, and patient satisfaction. RESULTS: There were no instances of unplanned removal of the cast by the patient or parent. No evidence of fracture displacement or angulation was seen in either group. The final carrying angle of the affected elbow was nearly identical of that of the normal, contralateral elbow in both groups (P=0.64). At the latest follow-up appointment, elbows in groups A and B had a similar mean arc of motion (156 vs. 154 degrees; P=0.45), and had achieved identical relative arc of motion of 99.6% and 99.5% of that of the normal, contralateral side, respectively (P=0.94). Main pain scores were low and comparable over the study period. All patients in both groups reported the highest rate of satisfaction at the eighth week of follow-up. CONCLUSIONS: The results indicate that children with nondisplaced supracondylar humeral fractures can be successfully managed with the use of a removable long-arm soft cast, maintaining fracture alignment and resulting in comparable rates of range of motion, pain, and patient satisfaction. The use of a removable immobilization that can reliably maintain fracture alignment and result in similar outcomes, while minimizing the risk of noncompliance, could be advantageous. Although we elected to remove the soft cast during a scheduled follow-up, it appears that such immobilization could be removed easily and safely at home, potentially resulting in a lower number of patient visits, decreased health care costs, and higher patient/parent satisfaction. LEVEL OF EVIDENCE: Level I.

How Many Patients Who Have a Clubfoot Treated Using the Ponseti Method are Likely to Undergo a Tendon Transfer?

BACKGROUND: The Ponseti method has become the standard of care for the treatment of idiopathic clubfoot. A commonly reported problem encountered with this technique is a relapsed deformity that is sometimes treated in patients older than 2.5 years by an anterior tibial tendon transfer (ATTT) to the third cuneiform. Presently, there is insufficient information to properly counsel families whose infants are beginning Ponseti treatment on the probability of needing later tendon transfer surgery. METHODS: All idiopathic clubfoot patients seen at the authors' institution during the study period who met the inclusion criteria and who were followed for >2.5 years were included (N=137 patients). Kaplan-Meier Survival analysis was used to determine the probability of survival without the need for ATTT surgery. In addition, the influence of patient characteristics, socioeconomic variables, and treatment variables on need for surgery was calculated. RESULTS: On the basis of the survivorship analysis, the probability of undergoing an ATTT remained below 5% for all patients at 3 years of age, but exceeded 15% by 4 years of age, increasing steadily afterwards such that by 6 years of age, the probability of undergoing an ATTT reached 29% of all patients. Overall, controlling for all other variables in the analysis, parent-reported adherence with bracing reduced the odds of undergoing surgery by 6.88 times, compared with parent-reported nonadherence (P<0.01). CONCLUSIONS: This is the first study to report the probability of undergoing ATTT surgery as a function of age using survivorship analysis following Ponseti clubfoot treatment. Although the overall probability reached 29% at 6 years, this was significantly reduced by compliance with bracing. This information may be useful to the clinician when counseling families at the start of treatment. LEVEL OF EVIDENCE: Level III-theraputic.

Lessons learnt from early failure of a patient trial with a polymer-on-polymer resurfacing hip arthroplasty.

Background and purpose - Hip resurfacing (HR) is a treatment option promoted for hip arthritis in young and active patients. However, adverse reactions to metal are a concern and the search for non-metallic bearing options proceeds. We present the first clinical study performed in patients using a newly developed hydrophilic polymer-on-polymer hip resurfacing device. Patients and methods - After performing extensive hip simulator tests, biocompatibility testing and animal tests (ISO 14242-1,3; 10993-3,4,5,10,11), approval was obtained from the IRB committee to enroll 15 patients in the first clinical study in humans using this experimental polymer-on-polymer hip resurfacing device. All surgeries were done by 2 experienced hip resurfacing surgeons. Clinical scores and standard radiographs as well as routine MRIs were obtained at regular intervals. Results - The surgical technique proved feasible with successful implantation of the new device using PMMA cement fixation on both sides without complications. Postoperative imaging revealed a well-positioned and well-fixed polymer resurfacing hip arthroplasty in all 4 initial cases. All 4 patients were free of pain and had good function for the first 2 months. However, in all 4 cases early cup loosening occurred between 8 and 11 weeks after surgery, necessitating immediate closure of the study. All 4 patients had a reoperation and were revised to a conventional THA. Retrieval analyses confirmed early cup loosening at the implant-cement interface in all 4 cases. The femoral components remained well attached to the cement. The periprosthetic tissues showed only small amounts of polymeric wear debris and there was only a very mild inflammatory reaction to this. Interpretation - Early cup loosening mandated a premature arrest of this study. After additional laboratory testing this failure mode was found to be the result of a small, yet measurable contraction in the cup size after exposing these implants to biological fluid divalent ion fluctuations in vivo. Currently used preclinical tests had failed to detect this failure mechanism. Modification of the polymer is essential to overcome these problems and before the potential of a polymer-on-polymer resurfacing arthroplasty may be further evaluated in patients.

Flexibility of thoracic spines under simultaneous multi-planar loading.

PURPOSE: The corrective potential of two posterior-only destabilization procedures for scoliosis deformity was quantified under single and multi-planar loading using cadaveric spines. METHODS: Ten full-length human cadaveric thoracic spines were mounted in an 8-df servohydraulic load frame. Cyclic, pure moments were applied in: (1) flexion-extension, (2) lateral bending, (3) axial rotation, (4) flexion-extension with axial rotation, and (5) lateral bending with axial rotation at 0.5°/s, to ±4 Nm. Each specimen was tested intact, and again after nine en bloc bilateral total facetectomies, and one, two, three, and four levels of Ponte osteotomies. Motion was measured throughout loading using optical motion tracking. RESULTS: Under single-plane loading, facetectomies and Ponte osteotomies increased thoracic spine flexibility in all three planes. Compared to total facetectomies, higher per-level increases were seen following Ponte osteotomies, with increases in total range of motion (total ROM) of up to 2.7° in flexion-extension, 1.4° in lateral bending, and 3.1° in axial rotation following each osteotomy. Compared to the facetectomies, four supplemental osteotomies increased total ROM by 23 % in flexion (p < 0.01) and 8 % in axial rotation (p < 0.01). Increases in lateral bending were smaller. Under multi-planar loading, each Ponte osteotomy provided simultaneous increases of up to 1.4°, 1.6°, and 2.2° in flexion-extension, lateral bending, and axial rotation. CONCLUSIONS: Ponte osteotomies provided higher per-level increases in ROM under single-plane loading than total facetectomies alone. Further, Ponte osteotomies provided simultaneous increase in all three planes under multi-planar loading. These results indicated that, to predict the correction potential of a surgical release, multi-planar testing may be necessary.

Temporal relation of meniscal tear incidence, severity, and outcome scores in adolescents undergoing anterior cruciate ligament reconstruction.

PURPOSE: Anterior cruciate ligament (ACL) rupture is increasingly common in adolescents. Time between ACL rupture and surgical reconstruction, surgical wait time, is related to concurrent meniscal tear incidence and possibly tear pattern. This study defines the relationship between meniscal tear characteristics and surgical wait time in adolescents with ACL rupture. METHODS: One-hundred and twenty-one consecutive adolescent (median age 16.1 years, range 9-19 years) ACL rupture patients undergoing primary ACL reconstruction were studied. All had documented surgical wait time, preoperative and 6-month post-operative outcome (Lysholm and pedi-IKDC) scores, and intraoperative meniscus tear characteristics. Meniscal tear severity was graded according to the Lawrence and Anderson system: non-surgical: grade 1; reparable: grade 2-3; irreparable: grade 4-5. Significant tears were defined as at least grade 2. RESULTS: Average age at surgery was 16.1 years. 48.7 % had surgical wait time greater than 6 months. 42.5 % of menisci were torn. With surgical wait time <6 months, there were more lateral than medial tears (48 vs 21 %, p = 0.001). With surgical wait time >6 months, medial tear incidence increased (50 vs 21 %, p < 0.001), there were more significant tears (63 vs 42 %, OR 2.3, p = 0.02), and preoperative Lysholm and pedi-IKDC scores were lower (58 vs 74, p < 0.001; 52 vs 61, p < 0.007). Scores were lower in patients with meniscus tears (63.8 vs 69.3, n.s.; 53.9 vs 60.5, p = .04). Patients with public insurance had risks of surgical wait time greater than 3 months (OR 12.4, p < 0.001) and 6 months (OR 7.8, p < 0.001), and of a significant meniscus tear (OR 2.5, p = 0.03). Six-month post-operative pedi-IKDC scores improved more in meniscus tear patients (28.4 vs 21, p = 0.05). CONCLUSIONS: This study shows a significant increase in medial meniscal tear incidence, decrease in preoperative scores, and worse tear severity with surgical wait time >6 months. Public insurance was a risk factor for longer surgical wait time and meniscus tear.

The Influence of Sex and Laterality on Clubfoot Severity.

BACKGROUND: Idiopathic clubfoot is bilateral in approximately 50% of cases and has been widely reported to affect males more frequently than females. Despite these observations, the correlation between sex and severity of the deformity has not been established. As well, the difference in severity between unilateral and bilateral clubfeet has not been extensively investigated. Therefore, the goals of the present study were to: (1) examine the relationship between sex and severity of deformity and (2) determine the relationship between laterality and severity of deformity. METHODS: The families of infants with idiopathic clubfoot deformity treated at our institution were prospectively invited to participate in this institutional review board-approved study. Severity of the deformity was assessed by a single surgeon for each patient using the Dimeglio criteria at the first clinic visit. After evaluating the distributions, the correlations were quantified by nonparametric analyses. RESULTS: Over 8 years, 240 infants met the inclusion criteria. There was no significant difference in the severity of deformity due to sex (P=0.61): the median Dimeglio score for males was 13 (variance 4.8) and for females, the median was 13.0 (variance of 5.1). In contrast, severity was distributed differently among unilateral versus bilateral patients. Although both unilateral and bilateral patients had a median Dimeglio score of 13, the ratio of bilateral patients was higher among those with moderate or very severe deformities compared with those with severe deformities (P<0.01). CONCLUSIONS: Although idiopathic clubfoot is commonly considered to affect male patients disproportionately, this is the first study to document no difference in severity due to sex. Further, this study demonstrated that on average, bilateral patients did not have increased severity, but presented with a larger range of severity than those patients with unilateral deformity. LEVEL OF EVIDENCE: Level III-prognostic.

So You Think You Don't Plunge? An Assessment of Far Cortex Drill Tip Plunging Based on Level of Training.

INTRODUCTION: Drill bit tip plunging past the far cortex places critical anatomical structures at risk. This study measured plunging past the far cortex based on level of training. The time required for screw placement when a depth gauge was used to measure bone tunnel depth was compared to the time required for screw placement when bone tunnel depth was measured in real time. MATERIALS AND METHODS: Thirty orthopedic surgery staff with 1-37 years of experience applied 10-hole plates to cadaveric limbs. Procedures were performed using two different drilling systems. Time and plunge depth were recorded. RESULTS: Penetration past the far cortex ranged from an average of 11.9 mm in the novice group to an average of 6.1 mm in the experienced group (P <0.001). The time required to drill and place a screw decreased by an average of 14 seconds per screw when depth gauge use was eliminated. CONCLUSIONS: Penetration past the far cortex occurred at all levels of training, but decreased with increased levels of experience. Real time measurement of bone tunnel length decreased total drilling time. The time saved with real time measurement decreased with increased level of experience.

Does Clubfoot Treatment Need to Begin As Soon As Possible?

INTRODUCTION: Parents of an infant with an idiopathic clubfoot deformity are often urged by their primary care physician to seek treatment as soon as possible. This advice frequently appears in many general pediatric and pediatric orthopaedic textbooks and monographs on the subject. This recommendation has not changed since the wide acceptance of the minimally invasive Ponseti method to treat clubfoot. We determined the correlations among patient-related variables, early treatment variables, and the age at which the patient was first seen to begin treatment. METHODS: Infants with moderate to very severe idiopathic clubfoot deformity were invited to participate. Age at which the patient presented to begin treatment was correlated against early treatment-related variables, including number of casts required, cast slippage, cast-related skin problems, brace-related skin problems, early noncompliance with brace wearing, and relapse before 1 year. Patient-related variables were also correlated against age at first visit. RESULTS: Over 7 years, 176 infants met the inclusion criteria. There were no significant differences in the aspects of the early management as a function of age at first visit, with the exception of cast slippage (P=0.05). CONCLUSIONS: The age at first visit influenced the incidence of cast slippage, but otherwise did not affect the early treatment of clubfoot. CLINICAL RELEVANCE: The treatment of idiopathic clubfoot deformity should not be considered an orthopaedic emergency, and parents whose infants are born with this deformity should be counseled accordingly.

Distal fibula fracture fixation: Biomechanical evaluation of three different fixation implants.

BACKGROUND: The goal of this study was to evaluate the biomechanical performance of three distal fibula fracture fixation implants in a matched pair cadaveric fibula model: (1) a 5-hole compression plate with lag screw, (2) a 5-hole locking plate with lag screw, and (3) the 6-hole tabbed-plate with locking screws. METHODS: Three-dimensional motions between the proximal and distal fibular segments were measured under cyclic valgus bending, cyclic compressive axial loading, and cyclic torsional external-rotation loading. During loading, strains were measured on the surfaces of each fibula near the simulated fracture site, and on the plate, to assess load transfer. Bone quality was quantified globally for each donor using bone mineral density (BMD) measured using Dual X-ray absorptiometry (DEXA) and locally at the fracture site using bone mineral content (BMC) measured using peripheral quantitative computed tomography (pQCT). RESULTS: Mean failure loads were below 0.2Nm of valgus bending and below 4Nm of external-rotational torque. Mean failure angulation was below 1degree for valgus bending, and failure rotation was below 7degrees for external-rotation. In the compression plate group, significant correlations were observed between bone quality (global BMD and local BMC) and strain in every one of the five locations (Pearson correlation coefficients >0.95, p<0.05). In contrast, in the locking and tabbed-plate groups, BMD and BMC correlated with far fewer strain locations. CONCLUSIONS: Overall, the tabbed-plate had similar construct stability and strength to the compression and locking plates. However, the distribution of load with the locking and tabbed-plates was not as heavily dependent on bone quality.