Although day surgery has a good patient satisfaction and safety profile, accurate episode-of-care costs (EOCC) calculation for of this procedure compared to standard same-day admission (SDA), while considering functional outcomes, is not well known. This study assesses the EOCC for patients with a THA while comparing DS and Same Day Admission (SDA) (with a 1-day hospitalization) pathways.

The episode-of-care cost (EOCC) of 50 consecutive day surgery and SDA patients who underwent a THA was evaluated. The episode-of-care cost was determined using a bottom-up Time Driven- Activity Based Funding method. Functional outcomes were measured using preoperative and postoperative Harris Hip Score (HHS).

Overall, the SDA THA cost 11% more than a DS THA. The mean total EOCC of DS THA was 9 672 CAD compared to 10 911 CAD in the SDA THA group. Both groups showed an improvement in HHS score following the procedure but patients in the DS group had a significantly higher postoperative HHS score and a significantly greater improvement in their HHS score postoperatively.

Day surgery THA is cost-effective, safe and associated with high patient satisfaction due to functional improvement. Providing policymakers the information to develop optimal financing methods is paramount for clinicians wishing to develop modern protocols, increase productivity while providing the optimal care for patients.

Porous surfaces on orthopaedic implants have been shown to promote tissue ingrowth. This study evaluated biological fixation of novel additively manufactured porous implants with and without hydroxyapatite coatings in a canine transcortical model.

Laser rapid manufacturing (LRM) Ti6Al4V cylindrical implants were built with a random interconnected architecture mimicking cancellous bone (5.2 mm diameter, 10mm length, 50–60% porous, mean pore size 450μm). Three groups were investigated in this study: as-built with no coating (LRM), as-built coated with solution precipitated hydroxyapatite (LRM-PA), and as-built coated with a plasma sprayed hydroxyapatite (LRM-PSHA). Implants were press-fit into a 5mm unicortical, perpendicular drill hole in the femoral diaphysis of the left and right femurs in 12 canines. Right femora were harvested for histology (SEM, bone ingrowth into implant within cortical region) and left femora for mechanical push-out testing (shear strength of bone-implant interface) at 4 and 12 weeks (N=6, un-paired Student's t-test, p=0.05).

For mean bone ingrowth, there was no significant difference between groups at 4 weeks (LRM, LRM-PA, LRM-PSHA: 41.5+8.6%, 51+5.5% and 53.2+11%, respectively) or 12 weeks (LRM, LRM-PA, LRM-PSHA: 64.4+2.8%, 59.9+7.6%, 64.9+6.4%, respectively). LRM and LRM-PA implants had more bone ingrowth at 12 weeks than 4 weeks (p < 0 .05). Mean shear strength of all implants at 12 weeks (LRM, LRM-PA, LRM-PSHA: 39.9+3.6MPa, 33.7+4.6MPa, 36+4.1MPa respectively) were greater than at 4 weeks (LRM, LRM-PA, LRM-PSHA: 21.6+2.8MPa, 20.7+1.1MPa, 20.2+2.5MPa respectively) (p < 0 .05). No significant difference was observed between all groups at 4 or 12 weeks.

Overall, this canine study confirmed the suitability of this novel additive manufacturing porous material for biological fixation by bone ingrowth. All implants exhibited high bone ingrowth and mechanical shear strength in this canine model. No difference was observed between uncoated and hydroxyapatite coated implants.

The pain of arthritic disorders occurs in a social and environmental context. Thus, the pain of arthritis not only can affect the patient, but also the spouse. Numerous investigations have shown that the spouses of individuals with persistent pain report lower levels of marital satisfaction, higher rates of depression and lower quality of life. For the vast majority of patients with osteoarthritis, total hip (THA) or total knee (TKA) arthroplasty results in a significant reduction in pain, emotional distress, disability and a significant improvement in their quality of life and function. Little is currently known about how these recovery-related changes impact on the spouse or the marital relationship.

Patients and their spouses were recruited within one-year following the arthroplasty surgery. Couples participated in a semi-structured interview and were each asked to recall their level of pain on a numerical rating scale from 1 to 10 before and after recovering from surgery, and provide a numerical rating score (10 points) for a set of seven questions pertaining to their level of disability in seven different activities of daily living. In addition, the spouses were asked to list in order of importance the ways in which the surgery of their spouse affected their overall quality of life. In total, 33 couples (66 respondents) answered the survey questionnaire. There were 17 male patients, 16 female patients who underwent 29 THAs and 4 TKAs.

With regard to pain, the spouses estimated their partner's pain, both preoperatively and at the time of the survey, to be at a significantly higher level than the patient's perception (p=0.05). The spouses perceived a greater improvement in family/home responsibilities, recreation and social activities, and in their occupation than that noted by the partner. After the arthroplasty, the spouses indicated that their lives had improved with respect to doing more activities/leisure (70%), because there partner had less suffering (61%), they had more independence/less caregiving (54%), it improved their marital relationship (54%), they had a better social/family life (27%) and they were able to travel (27%).

In addition to the patient, THA and TKA result in a significant improvement in quality of life and marital functioning of the spouse. This should not continue to be unrecognized as a significant benefit of the procedure.

Aims

The purpose of this study was to evaluate the biological fixation of a 3D printed porous implant, with and without different hydroxyapatite (HA) coatings, in a canine model.

Introduction

Porous surfaces developed over the past decades have been shown to promote tissue ingrowth. Hydroxyapatite (HA) coatings have been added to these porous coatings in an attempt to further augment bone ingrowth. The development of additive manufacturing techniques has allowed for precision in building these complex porous structures. The effect of supplemental HA coatings on these new surfaces is unclear. The purpose of this study is to evaluate the biological fixation of a novel 3D printed porous implant in a canine model. In addition, we evaluated the effect of different HA coatings on this 3D printed implant.

Dislocation is one of the most common complications after revision THA using the posterolateral approach. Although the cause of dislocation after revision THA is multifactorial, the historically high dislocation rates have been shown to be significantly reduced by closing the posterior capsule and by the use of large diameter (36 and 40 mm) femoral heads. The relative importance of each of these strategies on the rate of dislocation remains unknown. We undertook a study to determine if increasing femoral head diameter, in addition to posterior capsule closure would influence the dislocation rate following revision THA.

We retrospectively reviewed 144 patients who underwent a revision THA. We included all patients who underwent revision THA with closure of the posterior capsule and who had at least a 2-year minimum follow-up. We excluded patients undergoing a revision THA for dislocation or multistage revision for infection since these patients would likely have deficient posterior tissues. Forty-eight patients had a 28 mm femoral head, 47 had a 32 mm head and 49 patients had a 36 mm femoral head.

At a minimum follow-up of 2 years, there were 3 dislocations. There were no dislocations in the 28 mm group (0%), 2 in the 32 mm group (4%) and 1 in the 36 mm group (2%). All patients were successfully treated with a closed reduction. No patients had recurrent dislocation. Head size alone was not found to significantly decrease the risk of dislocation (28mm vs 32mm p=0.12; 28mm vs 36mm p=0.27; 32mm vs 36mm p=0.40).

Both large diameter heads and careful attention to surgical technique with posterior capsule closure can decrease the historically high dislocation rate after revision THA when utilizing the posterolateral approach. The additional use of a large diameter head did not have a significant impact on the already low dislocation rate. Capsular closure outweighs the effect of femoral head diameter in preventing dislocation following revision THA through a posterolateral approach.

Computer assisted surgery (CAS) has gained popularity in orthopaedics for both total knee (TKA) and total hip arthroplasty (THA) in the past decades as a stereotactic device that provides the surgeon with real-time feedback on implant position based on electromagnetic or infrared based instruments. The purpose of this study was to assess the effect of CAS on 30-day complication rates following THA and TKA.

The American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database was used to identify all patients that underwent THA and TKA from 2011 to 2013, as well as any complication they had within 30-days of their surgery. Univariate and multivariate regression analysis was used to compare the post-operative complications in patients whose surgery involved the use of CAS with those by conventional surgical techniques.

We identified 104,550 patients who had THA (42,275 patients) and TKA (62,275 patients) procedures in the database between 2011 and 2013. Computer Assisted Surgery was used in 1,120 THA and 2,173 TKA procedures. There were higher overall adverse events (OR 1.40, CI: 1.22–1.59) in the Conventional group when compared to CAS for TKA. The rate of overall minor events (OR 1.38, CI: 1.21–1.58) and requirements for blood transfusion (OR 1.44, CI: 1.25–1.67) were higher in the Conventional group compared to the CAS group for TKA. However, rate of re-operation was significantly higher in the CAS group for TKA (OR 1.60, CI: 1.15–2.25). The results also showed higher overall adverse events (OR 2.61, CI: 2.09–3.26) in the Conventional group when compared to CAS for THA. The rate of overall minor events (OR 2.72, CI: 2.16–3.42) and requirements for blood transfusion (OR 3.27, CI: 2.52–4.25) was higher in the Conventional group whereas superficial wound infections (OR 0.46, CI: 0.46–0.81) were shown to be higher in the CAS group. The result also showed slightly longer operative times in CAS for both THA and TKA.

This study analysed a large patient database involving multiple institutions and surgeons and found that, overall, the use off CAS in primary total hip and total knee arthroplasty reduced the number of adverse events in the first 30-days postoperatively, compared to conventional surgical techniques. However, CAS was associated with an increased number of reoperations, superficial infections and operating time. The clinical benefits and disadvantages of CAS should be considered by arthroplasty surgeons when determining the potential benefit-cost ratio of this technology.

Purpose

The purpose of this study was to compare and evaluate the cost-effectiveness of the MIS Anterolateral Approach to that of the MIS Posterolateral and MIS Direct Lateral Approach.

Purpose: The purpose of this study was to evaluate the clinical effectiveness and outcomes of the ‘abductor sparing’ MIS Anterolateral approach (MIS Watson Jones/G3) in comparison to the MIS Direct Lateral and MIS Posterolateral approaches in primary total hip arthroplasty.

Method: A multicentre, prospective, randomized controlled trial was designed to evaluate for the superiority of the new MIS Anterolateral approach (MIS Watson Jones/ G3). The sample size calculation was performed for alpha .05, power .90, to evaluate for effect size 0.5 in WOMAC using repeated measures analyses with baseline WOMAC as covariate. A total of 156 patients consented to participate in the trial and patients were assigned to MIS Antero-lateral approach or alternate MIS approach (MIS Direct Lateral or MIS Posterolateral). Patients were subjected to standardized anaesthetic and perioperative management protocols and were evaluated at standardized intervals to evaluate endpoints of early recovery (3 months) as well as endpoints of 12 and 24 months respectively. The primary outcome of interest was WOMAC, however secondary outcomes included SF-36, as well as parameters of health resource utilization and complications. Univariate and multivariate analyses were perfomed.

Results: Patient groups were found to be similar at baseline with regards to demographics and baseline quality of life outcomes (p> .05). Multivariate and repeated measures analyses demonstrated no superiority of the MIS Anterolateral approach on outcomes of WOMAC and other quality of life measures in comparison to MIS Direct Lateral and MIS Posterolateral approaches (p> .05). Health care resource utlization was also similar with length of stay, blood transfusion requirements and complications (p> .05).

Conclusion: Our multicentre, prospective, randomized clinical trial demonstrates that the MIS Anterolateral approach is not superior to alternate MIS surgical approaches when evaluating outcomes of quality of life, complications, and health resource utilization. Surgeons should consider these outcomes, complications, and other relevant advantages and disadvantages of select surgical approaches when deciding on a technique for use in their orthopaedic practice.

Purpose: Previous studies have shown the utility of the bisphosphonate zoledronic acid (ZA) by systemic administration and local delivery for enhancing local bone formation with porous implants. The purpose of this study was to quantify the long term effect of local delivery of ZA on bone growth within and around porous tantalum implants one year after surgery.

Method: Hydroxyapatite coated porous tantalum (Trabecular Metal^™, Zimmer Inc) implants measuring 9 mm in diameter and 90 mm in length were used in a canine bilateral femoral intramedullary model. Commercially pure ZA (Novartis Pharma) of either 0.05 mg or 0.20 mg ZA was applied to implants. Bilateral surgery was performed on 10 dogs – all 10 with a control implant on one side and 5 each with either a 0.05 mg or 0.20 mg ZA-dosed implant on the contralateral side. After one year, the femora were harvested and processed for undecalcified thin section histology and backscattered scanning electron microscopy. Statistical analysis was done using the student’s t tests and multiple two-level hierarchical models.

Results: The 160 histologic sections revealed that compared with controls, there was more intramedullary bone around implants dosed with both 0.05 mg ZA (+91%, p< 0.001) and 0.20 mg ZA (+115%, p< 0.001). Bone ingrowth was present in all sections and was more abundant within 1.5mm of the implant periphery. The 0.20 mg ZA dose resulted in more net intramedullary bone formation than the 0.05 mg dose (+41%, p< 0.006). The mean extent of bone ingrowth for implants dosed with 0.20 mg ZA was significantly greater than controls (+32%, p< 0.003) and also greater than for implants dosed with 0.05 mg ZA (+47% for the area within 1.5 mm of the periphery, p< 0.002).

Conclusion: This study demonstrated that the enhanced net bone formation that occurs due to local elution of ZA from porous implants was sustained out to 1 year after surgery. A notable dose response was also demonstrated. The peri-implant response was confined to within a few millimeters of the implant suggesting that ZA elution remains localized. This study supports the concept of using ZA-dosed implants for enhancing net bone formation within and around noncemented implants.

Purpose: The treatment and prognosis of labral tears secondary to femoroacetabular impingement depends on the severity of the labral injury and whether or not there is concomitant injury and delamination of the adjacent articular cartilage. At present, there is no simple and reproducible technique to determine if there is delamination of the adjacent articular cartilage. We undertook a study to determine if the preoperative presence of a previously undescribed radiographic finding, a “delamination cyst”, correlated with delamination of the articular cartilage at the time of hip arthroscopy.

Method: The preoperative radiographs of 125 consecutive hip arthroscopies in which a labral tear was identified intraoperatively were retrospectively reviewed.. In each case an anteroposterior (AP) pelvis and AP, lateral and frog lateral hip radiographs were evaluated for the presence of delamination cysts, perilabral cysts, abnormalities of the femur and acetabulum, as well as arthritic changes. A “delamination cyst” was defined as a subchondral cyst either directly adjacent to a perilabral cyst, or in relation to a subchondral crack in the anterolateral portion of the acetabulum. These findings were then compared and correlated to the intraoperative arthroscopic findings.

Results: We identified 16 patients with delamination cysts on radiographs and 15 patients with delamination of the acetabulum on arthroscopy. A strong correlation was found between the preoperative radiographic presence of a delamination cyst and acetabular delamination at the time of arthroscopy – sensitivity of 93.3%, specificity of 98.8%, positive predictive value of 93% and a negative predictive value of 99% (p=0.034). No other radiographic findings were associated with the status of the articular cartilage.

Conclusion: A “delamination cyst” is a previously undescribed and novel radiographic sign that can accurately predict preoperatively which patients with labral tears have associated acetabular cartilage delamination or chondral damage. Delamination cysts can be easily identified on plain radiographs without performing any special imaging or invasive infiltrations. Identifying these cysts preoperatively can aid the surgeon in selecting the appropriate surgical procedure and help predict the patient’s prognosis following the planned surgical procedure.

Purpose: The bisphosphonate Zoledronic acid (ZA) is effective for increasing net bone formation within and around implants when directly eluted from implants. The extent to which this occurs or whether ZA is more widely distributed through diffusion into the circulation is unknown. The purpose of this study was to utilize 14C-labeled ZA to quantify the localization and skeletal distribution of ZA in a canine intramedullary implant model.

Method: A solution of 100μg 14C-labeled ZA was evenly distributed onto each implant surface of three hydroxyapatite coated porous tantalum (Trabecular Metal^™, Zimmer Inc) implants measuring 5 mm in diameter and 50 mm in length. The implants were inserted within the left femoral intramedullary canal of an adult mongrel dog and left in situ for 6 weeks. The 3 femora with implants and all the other long bones were harvested, dried, pulverized into a fine powder and disolved in HCl. This solution was then placed in a scintillation cocktail (Ultima Gold AB, Perkin Elmer USA) and analyzed with a Packard Tri-Carb 2100TR liquid scintillator spectrometer. Data were analyzed with student’s t tests and nested analyses of variance with p=0.05.

Results: Very high amounts of ZA were present within the bone samples immediately adjacent to the implants – range 243 – 1487 ng ZA/g of bone, mean of 800 ng ZA/g. By 1 cm proximal or distal to the implant, the values diminished by up to an order of magnitude. All other bone samples contained very low amounts of 14C, (range, 0.8 – 22.6 ng ZA/g; mean 6.5 ng ZA/g), indicating diffusion of ZA into the circulation and a level of systemic distribution. This is about 11-fold less in magnitude (p< 0.0001).

Conclusion: Local elution of ZA directly from an implant results in half of the ZA being distributed locally in the femur with the rest being distributed throughout the skeleton, at levels that are much less than the therapeutic dose required to appreciably affect bone remodeling or cause complications. postoperative time periods.

There has been a longstanding need for a structural biomaterial that can serve as a bone graft substitute or implant construct and is effective for fixation by bone ingrowth. A porous tantalum material was developed to address these issues. The purpose of this paper and presnetation is to describe the properties and 2 to 5 year clinical results of porous tantalum in various reconstructive orthopaedic procedures.

Porous tantalum has been used to manufacture primary and revision acetabular cups, acetabular augments, tibial and patella implants, patellar augments, structural devices for the treatment of osteonecrosis, and spinal fusion implants. Clinical follow-up includes: 2–5 year clinical and radiographic evaluation of: 414 monoblock cups in primary THA, 36 monoblock cups and 587 revision hemispheres used in revision THR, 16 hips revised with acetabular augments and revision hemispheres; 2 to 4 years for 101 tibial implants used in primary TKR and 69 patellas used in cementless TKR; 2–4 years for 11 patellar augments in salvage TKR, 1–5 years for 53 revision TKRs using knee spacers; 1–4 years for 91 osteone-crosis hip implants; and for 15 cervical fusion cases.

This innovative tantalum implant material with trabecular architecture possesses advantages in stiffness, friction coefficient, porosity, rate and extent of tissue ingrowth, and versatility in manufacturing of structural devices. It has been clinically validated in numerous and diverse reconstructive procedures.

Patient postoperative outcome can be accurately predicted by the patient’s preoperative HHS or WOMAC score. Prospective, cohort studies of one hundred and seventy-five THAs. SF-36, WOMAC and Harris Hip Score (HHS)questionnaires were used to determine pre-operative and two year final outcome. Student’s t-test, 95% confidence intervals, receiver operator characteristic curves, simple regression analysis and probability were measured. Patients with a HHS = sixty-five pre-operatively had a 100% probability of having an excellent result postoperatively. A preoperative HHS value of thirty-four, and preoperative WOMAC (physical function) value of fifty were the best cutoff points to attain a significantly better postoperative functional outcome.

Total hip arthroplasty (THA) has been well documented to enhance patient function, but patient outcome is dependant on preoperative statuts. The exact timing of surgery to optimize patient outcome after THA remains unknown. This study determines the ideal timing for surgery to obtain the best possible functional outcome.

Prospective, multicenter, cohort studies of one hundred and seventy-five identical, cemented THAs. General health (SF-36) and disease specific (WOMAC and Harris Hip Score(HHS)) questionnaires were used to determine preoperative and two year final outcome. Student’s t-test, 95% confidence intervals, receiver operator characteristic curves, simple regression analysis and probabilty were measured.

All functional scores were improved significantly postoperatively (p< 0.001). Patients with a HHS = sixtyfive preoperatively had a 100% probability of having an excellent result postoperatively. A preoperative HHS value of thirty-four, and preoperative WOMAC (physical function) value of fifty were the best cutoff points to attain a significantly better postoperative functional outcome.

Patient postoperative outcome can be accurately predicted by the patient’s preoperative HHS or WOMAC score. Optimization of surgical timing, by prioritizing wait lists or deciding to treat the arthritis operatively, based on these preoperative score guidelines will help ensure an excellent outcome post THA.

Purpose: A porous tantalum cylindrical shaped implant (Osteonecrosis Intervention Implant, Zimmer, Warsaw, IN) has been designed to provide subchondral bony support of the subchondral plate, be osteoconductive and allow revascularization of an osteonecrotic femoral head. This study evaluates retrieved implants obtained at the time of conversion to total hip arthroplasty to determine the ability of this device to fulfill its objectives. |

Methods: Eighteen femoral heads with the tantalum implant still in situ were evaluated with contact radiographs and scanning electron microscopy to assess femoral head and bony anatomy, bone growth into the implant and femoral head revascularization. Retrievals from 12 males and 6 females with an average age of 46 years old (range, 31–61) and Stage I or II osteonecrosis were evaluated. |

Results: At a mean of 13.4 months (range, 3–36) postoperatively, all femoral heads demonstrated subchondral collapse. The bone surrounding the implant remained necrotic with no evidence of revascularization or healing. Ingrowth was marginal and averaged less than 5%.

Conclusions: This tantalum implant in its present design and surgical technique does not appear to uniformly provide structural support and promote healing of early osteonecrosis of the femoral head. This retrieval study suggests that successful results with this implant in certain cases of early osteonecrosis may be more attributable to the surgical technique requiring a core decompression, rather than the implant itself. |

Labral tears are increasingly recognized as a source of hip pain. These rarely occur in normal hips, but in individuals with subtle femoral deformities. Anterior impingement of the femoral neck on the acetabulum due to loss of anterior offset results in a labral tear in active individuals. Future surgeries should be directed at this anterior offset deficiency in order to completely alleviate pain and prevent further recurrences.

To determine the incidence of anterior hip impingement and femoral pathology in patients undergoing hip arthroscopy for labral tear.

Anterior labral tears occur in the presence of abnormal femoral anatomy, which results in anterior hip impingement.

Future treatment of labral tears should include addressing the hip impingement.

Labral tears of the hip are increasingly being recognized as a source of hip pain in young, active individuals. Athroscopic labral debridement is commonly associated with poor results. As a result, it is likely that other hip pathology is present at the time of labral tear. The purpose of this study was to determine the incidence of anterior hip impingement secondary to a pistol grip deformity in patients undergoing hip arthroscopy for labral tears.

The charts and radiographs of forty consecutive patients who underwent hip arthroscopy were evaluated. X-rays were evaluated for presence of acetabular or femoral pathology. Femoral pathology was then graded based on degree of slip and posterior slip angle.

All patients who underwent hip arthroscopy for labral tears had abnormal femoral or acetabular anatomy. In those patients without acetabular dysplasia, a pistol grip deformity of the femoral head was present in all cases. Evidence of anterior hip impingement with osteophyte formation was present in ninety-two percent. In these patients, hip arthroscopy results in complete resolution of mechanical symptoms, but hip pain was still present.

Labral tears of the hip appear to be secondary to anterior femoral impingement. This is analogous to a rotator cuff tear in the presence of shoulder impingement. Anterior impingement of the femoral neck on the acatabulum due to an anterior femoral offset deformity results in both pain and labral tears. Future surgeries should be directed at this anterior offset deficiency in order to prevent recurrent injuries or residual pain.

This is the first study to determine if closure of the posterior capsule during revision total hip arthroplasty (THA) results in a reduction in the historically high dislocation rate. Seventy-nine consecutive patients undergoing revision THA with a posterolateral approach and closure of the posterior hip capsule were retrospectively reviewed. At a mean follow-up of fifty-seven months (range twenty-four to one hundred and twenty months), there were only two dislocations (2.5%). The historically high dislocation rates with the posterolateral approach in revision THA, can be significantly decreased with posterior capsular closure from approximately 15% to 2.5%.

To determine if closure of the posterior capsule during revision total hip arthroplasty results in a reduction in the historically high dislocation rate.

The dislocation rate after revision THA with a posterior approach can be minimized by repairing the posterior capsule and rotators.

The historically high dislocation rates with the pos-terolateral approach in revision THA, can be significantly decreased with posterior capsular closure from approximately 15% to 2.5%.

A retrospective study was carried out to review seventy-nine consecutive revision THAs. In all cases, the surgery was done by a single surgeon using the posterolateral approach. In every case, the posterior capsule was meticulously repaired at the end of the procedure. All patients had a minimum two- year follow-up and no patients were lost to follow up.

At a mean follow-up of fifty-seven months (range twenty-four to one hundred and twenty months), there were only two dislocations (2.5%). Both dislocations occurred early postoperatively were anterior. One occurred in a high risk case- a proximal femoral replacement with a trochanteric osteotomy, high hip center and skirted head. The other was due to a technical error, with the cup being excessively anteverted. There were no late dislocations or subluxations.

The dislocation rate after revision THA with a posterior approach can be minimized by balancing soft tissues, correct implant alignment and repairing the posterior capsule and rotators.

Purpose: Acetabular labral tears are most commonly associated with minor or atraumatic events. As a result, it is likely that these tears occur in the presence of an abnormal hip joint. The purpose of this investigation was to establish whether anterior hip impingement, secondary to an anterior femoral offset deficiency from a pistol grip deformity, was a common and poorly recognized cause of acetabular labral tears.

Methods: Sixty-five consecutive patients who underwent a hip arthroscopy and were found to have a labral tear were evaluated. Preoperative hip radiographs were evaluated for abnormalities of the femur and /or acetabulum. The patient’s outcome with respect to resolution to pain and mechanical symptoms was assessed.

Results: All labral tears identified at the time of hip arthroscopy were found to be located anteriorly. A pistol grip deformity of the proximal femur was identified on the preoperative radiographs in 92% of the patients. Labral excision resulted in complete resolution of hip pain in only 8 (28%). With the remaining 72% experiencing mild or moderate pain.

Conclusions: Acetabular labral tears are the result of repetitive femoral-acetabular impingement, from a pistol grip deformity, with eventual tearing of the labrum from a relatively minor trauma. This is analogous to a rotator cuff repair in the shoulder that is secondary to repetitive impingement by the acromium. Decompression or correction of the anterior hip impingement should routinely be considered at the time of labral surgery to provide complete relief of symptoms and diminish the risk of future joint degeneration.

The effect of zoledronic acid on bone ingrowth was examined in an animal model in which porous tantalum implants were placed bilaterally within the ulnae of seven dogs. Zoledronic acid in saline was administered via a single post-operative intravenous injection at a dose of 0.1 mg/kg. The ulnae were harvested six weeks after surgery. Undecalcified transverse histological sections of the implant-bone interfaces were imaged with backscattered scanning electron microscopy and the percentage of available pore space that was filled with new bone was calculated. The mean extent of bone ingrowth was 6.6% for the control implants and 12.2% for the zoledronic acid-treated implants, an absolute difference of 5.6% (95% confidence interval, 1.2 to 10.1) and a relative difference of 85% which was statistically significant. Individual islands of new bone formation within the implant pores were similar in number in both groups but were 69% larger in the zoledronic acid-treated group. The bisphosphonate zoledronic acid should be further investigated for use in accelerating or enhancing the biological fixation of implants to bone.

We designed an in vivo study to determine if the superimposition of a microtexture on the surface of sintered titanium beads affected the extent of bone ingrowth. Cylindrical titanium intramedullary implants were coated with titanium beads to form a porous finish using commercial sintering techniques. A control group of implants was left in the as-sintered condition. The test group was etched in a boiling acidic solution to create an irregular surface over the entire porous coating. Six experimental dogs underwent simultaneous bilateral femoral intramedullary implantation of a control implant and an acid etched implant. At 12 weeks, the implants were harvested in situ and the femora processed for undecalcified, histological examination. Eight transverse serial sections for each implant were analysed by backscattered electron microscopy and the extent of bone ingrowth was quantified by computer-aided image analysis. The extent of bone ingrowth into the control implants was 15.8% while the extent of bone ingrowth into the etched implants was 25.3%, a difference of 60% that was statistically significant.

These results are consistent with other research that documents the positive effect of microtextured surfaces on bone formation at an implant surface. The acid etching process developed for this study represents a simple method for enhancing the potential of commonly available porous coatings for biological fixation.