The Accuracy and Absolute Reliability of a Knee Surgery Assistance System Based on ArUco-Type Sensors.

Recent advances allow the use of Augmented Reality (AR) for many medical procedures. AR via optical navigators to aid various knee surgery techniques (e.g., femoral and tibial osteotomies, ligament reconstructions or menisci transplants) is becoming increasingly frequent. Accuracy in these procedures is essential, but evaluations of this technology still need to be made. Our study aimed to evaluate the system's accuracy using an in vitro protocol. We hypothesised that the system's accuracy was equal to or less than 1 mm and 1° for distance and angular measurements, respectively. Our research was an in vitro laboratory with a 316 L steel model. Absolute reliability was assessed according to the Hopkins criteria by seven independent evaluators. Each observer measured the thirty palpation points and the trademarks to acquire direct angular measurements on three occasions separated by at least two weeks. The system's accuracy in assessing distances had a mean error of 1.203 mm and an uncertainty of 2.062, and for the angular values, a mean error of 0.778° and an uncertainty of 1.438. The intraclass correlation coefficient was for all intra-observer and inter-observers, almost perfect or perfect. The mean error for the distance's determination was statistically larger than 1 mm (1.203 mm) but with a trivial effect size. The mean error assessing angular values was statistically less than 1°. Our results are similar to those published by other authors in accuracy analyses of AR systems.

The Tibial Tubercle-Trochlear Groove Distance/Trochlear Dysplasia Index Quotient Is the Most Accurate Indicator for Determining Patellofemoral Instability Risk.

PURPOSE: The primary aim of our study was to evaluate diagnostic accuracy of the tibial tubercle-trochlear groove (TT-TG) distance relative to associated quotients produced from trochlear width (TT-TG distance/TW) and trochlear dysplasia index (TT-TG distance/TDI) for detecting patellofemoral instability. Secondary aims included identifying thresholds for risk and comparing differences between cases and controls. METHODS: Consecutive sampling of electronic medical records produced 48 (21 males, 27 females) patellofemoral instability cases (19 ± 7 years old) and 79 (61 males, 18 females) controls (23 ± 4 years old) who had a history of isolated meniscal lesion, as evaluated by magnetic resonance imaging. Standardized methods were employed with measurements executed in a blinded and randomized manner. A receiver operating characteristic curve assessed accuracy by area under the curve (AUC). The index of union (IU) was employed to identify a threshold for risk. Two-sample t-tests examined group differences. P < .05 denoted statistical significance. RESULTS: The AUC values were .69 (.60, .79) for TT-TG distance, .81 (.73, .88) for TT-TG distance/TW, and .85 (.78, .91) for TT-TG distance/TDI. Thresholds were 14.7 mm for TT-TG distance, .36 for TT-TG distance/TW, and 1.88 for TT-TG distance/TDI. Cases demonstrated statistically significant (P < .001) greater values for each measure compared with controls: TT-TG distance (15.8 ± 4.2 mm vs 12.9 ± 3.6 mm, [1.4, 4.3]); TT-TG distance/TW (.51 ± .24 vs .31 ± .09, [.13, .27]); TT-TG distance/TDI (3.07 ± 1.55 vs 1.7 ± .7, [.9, 1.84]). CONCLUSION: The TT-TG distance, TT-TG distance/TW, and TT-TG distance/TDI measures were 69%, 81%, and 85%, respectively, accurate for determining patellofemoral instability risk. Thresholds for risk were 14.7 mm for TT-TG distance, .36 for TT-TG distance/TW, and 1.88 for TT-TG distance/TDI. The thresholds reported in this study may help in advancing clinical decision-making. LEVEL OF EVIDENCE: Level III, diagnostic retrospective comparative observatory trial.

Tibial Tubercle-Trochlear Groove Distance Is a Reliable and Accurate Indicator of Patellofemoral Instability.

BACKGROUND: Tibial tubercle-trochlear groove (TT-TG) distance is a measurement generally made on CT scans that is commonly used to quantify the risk of patellofemoral instability (PFI); however, its interrater reliability and accuracy as an indicator of PFI in patients is poorly characterized. QUESTIONS/PURPOSES: The purposes of our study were (1) to primarily analyze interrater reliability of the TT-TG distance among orthopaedists with varied experience as measured by MRI, (2) to secondarily compare TT-TG distances between PFI and control groups, and (3) to determine an accurate TT-TG distance threshold indicative of PFI. METHODS: The electronic medical records of a senior fellowship-trained orthopaedic sports medicine surgeon were surveyed between 2012 and 2016 for patients who had experienced at least one episode of patellar subluxation or dislocation, who reported no other knee-related history, and who underwent MRI due to persistent PFI signs and symptoms. The records of 48 PFI patients (23 males, 25 females; 19 ± 4 years of age) were compared with 83 controls (60 males, 23 females; 31 ± 8 years of age) having no history of PFI, presenting with an isolated meniscal lesion as determined from MRI and treated by the same orthopaedist during this time. All records meeting study criteria were consecutively included to offset selection bias of the retrospective analysis. Two sports medicine fellows, one who had just completed orthopaedic residency training, and another with a year of experience after residency, and a sports medicine subspecialist with more than 15 years of experience in practice independently recorded TT-TG distance, indicative of tibial tubercle lateralization relative to the femoral trochlea, to the nearest millimeter (mm) in a blinded and randomized fashion. Intraclass correlation coefficient computed interrater reliability accompanied by standard error of measurement (SEM); a one-tailed, two-sample t-test analyzed group differences with accompanying effect size per Cohen's d; receiver operating characteristic (ROC) curve determined accuracy and threshold for PFI risk. A p value < 0.05 denoted statistical significance. RESULTS: Interrater reliability was excellent, at 0.93 (95% confidence interval [CI], 0.84-0.97; SEM = 0.6 mm) for PFI patients and 0.95 (95% CI, 0.91-0.97; SEM = 0.4 mm) for controls. Distance was greater (95% CI, 2-5; p < 0.001) in PFI patients (14 ± 4 mm; range = 7-24 mm) than controls (10 ± 3 mm; range = 3-19 mm) with an effect size of 1 (95% CI, 0.3-2). Area under the ROC curve was 0.75 (95% CI, 0.66-0.83) and threshold was 13 mm (sensitivity = 0.52, 1-specificity = 0.25), suggesting the measure is a fairly accurate indicator of risk and values of 13 mm or greater are better suited to rule in PFI. Respective positive and negative likelihood ratios of 2 and 0.6 at this threshold confirm that this distance yields a small increase in probability for PFI and a minimal decrease in probability for risk; specifically, a 13-mm TT-TG distance is two times more likely to be found in patients with PFI. Furthermore, this threshold is estimated to increase a correct PFI diagnosis by approximately 15%. CONCLUSIONS: The MRI-specific TT-TG distance, based on a single measurement using cartilaginous-tendon landmarks within a standardized trochlear range, is reliable as performed by orthopaedists of varied experience. Patients with PFI display a 4-mm greater distance than controls, which may represent a difference large enough for clinicians to discern in practice using MRI. A 13-mm TT-TG distance is two times more likely seen in patients with PFI. However, this threshold increases a correct PFI diagnosis by only about 15%; therefore, clinical decision-making should not be influenced by this criterion alone and instead used in conjunction with other relevant variables. LEVEL OF EVIDENCE: Level IV, diagnostic study.

Isolated Polyethylene Exchange With Increased Constraint Is Comparable to Component Revision TKA for Instability in Properly Selected Patients.

BACKGROUND: Symptomatic instability following total knee arthroplasty (TKA) is a leading cause of early failure. Most reports recommend component revision as the preferred treatment because of poor outcomes and high failure rates with isolated tibial polyethylene insert exchange (ITPIE). However, these ideas have not been tested in modern implant systems that allow insert constraint to be increased. METHODS: We retrospectively reviewed 90 consecutive patients with minimum 2-year (mean 3.7 years) follow-up who underwent revision TKA for instability at a single institution. Mean age was 62.0 years (range, 41 to 83 years), and 73% of patients were women. Forty percent of patients were treated with ITPIE when standardized preoperative and intraoperative criteria were met; 60% underwent revision of one or both components when these criteria were not met. RESULTS: Patients experienced significant improvements in Knee Society (KS) knee (48.4 to 82.6; P < .001) and function (49.0 to 81.0; P < .001) scores. There were no significant differences in improvements in KS knee scores (38.1 vs 33.1; P = .18), KS function scores (36.0 vs 34.0; P = .63), or arc of motion (5° vs 6°; P = .88) between those treated with ITPIE and component revision. Failure rates were 19.4% in the ITPIE group vs 18.5% in the component revision group (odds ratio, 1.06; P = .91). Re-revision rates were significantly lower (6.3% vs 30.8%; odds ratio, 0.15; P = .004) when polyethylene insert constraint was increased. CONCLUSION: In selected patients, ITPIE is not inferior to component revision at addressing symptomatic instability following TKA. Degree of constraint should be increased whenever possible during revision surgery for instability.

Revision Arthroplasty for the Management of Stiffness After Primary TKA.

BACKGROUND: The aim of this study was to evaluate the results of revision surgery for the treatment of stiffness after total knee arthroplasty (TKA). METHODS: An IRB-approved retrospective review was performed to identify patients who were revised due to stiffness after a primary TKA. Patients were included when at least one major component had to be revised due to stiffness after primary TKA with a minimum follow-up of 2 years. Patients with history of previous infection and those treated with isolated polyethylene exchange were excluded. RESULTS: The study group involved 42 knees. Mean follow-up was 47 months (24-109 months). Mean flexion contracture improved from 9.7° (0°-35°) preoperatively to 2.3° (0°-20°) postoperatively (P < .00). Mean flexion improved from 81.5° (10°-125°) preoperatively to 94.3° (15°-140°) postoperatively (P .02). Mean range of motion improved from 72.0° preoperatively (10°-100°) to 92° (15°-140°) postoperatively (P < .00). Mean Knee Society knee scores improved from 43.9 points (15-67) preoperatively to 72.0 points (50-93) at latest follow-up and mean Knee Society Function scores improved from 48.7 (35-80) preoperatively to 70.1 points (30-90) postoperatively. Pain improved in 73% of the patients. CONCLUSION: Revision surgery appears to be a reasonable option for patients presenting with pain and stiffness after TKA. However, the benefits may be modest as the outcomes still do not approach those achieved with primary TKA.

Evaluation of lower limb kinetics during gait, sprint and hop tests before and after anterior cruciate ligament reconstruction.

BACKGROUND: The purpose of this study was to evaluate the functional status prior to and at different times after anterior cruciate ligament reconstruction (ACLR), and to analyze the changes in the kinetic patterns of the involved and uninvolved lower limb during gait, sprint and three hop tests. MATERIALS AND METHODS: Seventy-four male patients with an ACL injury were included in the study. All patients performed a standardized kinetic protocol including gait, sprint and three hop tests (single-leg hop, drop vertical jump and vertical jump tests), preoperatively and at 3, 6, and 12 months after ACLR with a semitendinosus gracilis tendon autograft. Measurements were performed with two force plates. The lower limb symmetry index (LSI) was calculated to determine whether a side-to-side leg difference was classified as normal (LSI >90%) or abnormal (LSI <90%). RESULTS: The LSI presented high values (>90%) at almost all times before and after ACLR in gait, sprint and single-leg hop tests (p < 0.005), with a tendency to increase postoperatively. A lower LSI was observed (<90%) in tests where both extremities were tested simultaneously, such as the drop vertical jump and vertical hop tests (p < 0.05). CONCLUSION: We observed a tendency to increase symmetry restoration in the kinetics of the involved and uninvolved limb up to twelve months after ACLR, especially in those tests, in which, both limbs were tested individually (gait analysis, sprint and single-leg hop tests). Therefore, the isolation of the involved and uninvolved limb seems to be a critical component in the functional rehabilitation and evaluation of patients before and after ACLR. LEVEL OF EVIDENCE: level III.

Maintaining the Physiological Lateral Flexion Gap in the Kinematically Aligned TKA Does Not Compromise Clinical Outcomes at One-Year Follow-Up.

Background: Instability is a common cause of (total knee arthroplasty) TKA failure, which can be prevented by achieving proper gap balance during surgery. There is no consensus on the ideal gap balance in TKA, and different alignment philosophies result in varying soft-tissue tightness. Traditional TKA aims for symmetric compartment balance, while kinematic alignment (KA) restores anatomy and accepts asymmetric flexion gaps. This study evaluated the impact of these philosophies on the flexion gap balance and clinical outcomes. Methods: A retrospective review of 167 patients who received true or restricted KA robotic-assisted TKA with at least one year of follow-up was conducted. The groups were based on intraoperative flexion gap differences: symmetric (0-1 mm) (n = 94) and asymmetric (2-5 mm) (n = 73). Results: Preoperative demographics and postoperative clinical and functional scores were compared. Both groups were similar in demographics and preoperative scores. True KA alignment was more likely to result in an asymmetric flexion gap, while restricted KA produced symmetric gaps. Conclusions: The study found no adverse effects from the physiological asymmetric flexion gap, with clinical and functional outcomes comparable to symmetric gaps. A 5 mm difference between the medial and lateral gap width did not negatively impact the outcomes. True KA more frequently results in a physiological asymmetric flexion gap.

Legg-Calvé-Perthes disease: role of isolated adductor tenotomy?

BACKGROUND: The aim of the study was to compare the radiological results at maturity of patients with Legg-Calve-Perthes disease, treated either by a uniform conservative treatment or by an adductor longus tenotomy. METHODS: The study cohort comprised 349 hips, mean age 4.4 years. Patients were classified in two different groups depending on the treatment performed. The conservative group (Group I) consisted of 318 hips that had been treated by physical therapy and abduction cast/brace, with a mean age 4.3 years (range 1-10). The tenotomy group (Group II) consisted of 31 hips (treated conservatively but developed an adduction contracture limited to 30°), which had been treated by adductor longus tenotomy with a mean age of 6.2 years (range 2-9). Hip range of motion and radiographic studies were performed at the time of admission. The extent of femoral epiphyseal involvement was assessed at each follow-up by the method of Herring. The final outcomes were assessed at skeletal maturity according to the Stulberg classification system. RESULTS: Only one patient (two hips) from Group II experienced an improvement in abduction, which was maintained throughout the follow-up until complete the healing of Legg-Calvé-Perthes disease was achieved. In the remaining 29 hips, we observed a progressive loss of ROM previous to 4.3 months from the tenotomy. According to the Stulberg classification, we did not find differences between both groups at final follow-up (p > 0.05). CONCLUSIONS: These preliminary data suggest that the isolated tenotomy of the adductor longus tendon does not modify the natural evolution of Legg-Calvé-Perthes disease.

Fixed Flexion Contracture Can Successfully Be Addressed with Exact Preservation of the Femoral Joint Line and Only Minimal Increase of Tibia Resection in the Concept of Kinematically Aligned Total Knee Arthroplasty.

The aims of this study were to evaluate the outcomes of patients undergoing kinematic alignment (KA) robot-assisted (RA) total knee arthroplasty (TKA) with and without preoperative fixed flexion contracture (FFC) and address whether additional resection of the proximal tibia is required to address FFC. A retrospective review from 147 consecutive patients who received an RA-TKA with KA and a minimum one-year follow-up was performed. Preop and postop clinical and surgical data were collected. Groups were set based on preoperative extension deficits: group 1 (0-4°) (n = 64), group 2 (5-10°) (n = 64) and group 3 (>11°) (n = 27). There were no differences in patient demographics among the three groups. In group 3, the mean tibia resection was 0.85 mm thicker than group 1 (p < 0.05) and the preoperative extension deficit was improved from -17.22° (SD 3.49) preop to -2.41° (SD 4.47) postop (p < 0.05). Our results demonstrate that FFC can successfully be addressed in the RA-TKA with KA and rKA and that no additional femoral bone resection is needed to achieve full extension in patients with preoperative FFC when compared with patients without FFC. Only a slight increase in the amount of tibial resection was observed, but this was less than one millimetre.

Integration of Square Fiducial Markers in Patient-Specific Instrumentation and Their Applicability in Knee Surgery.

Computer technologies play a crucial role in orthopaedic surgery and are essential in personalising different treatments. Recent advances allow the usage of augmented reality (AR) for many orthopaedic procedures, which include different types of knee surgery. AR assigns the interaction between virtual environments and the physical world, allowing both to intermingle (AR superimposes information on real objects in real-time) through an optical device and allows personalising different processes for each patient. This article aims to describe the integration of fiducial markers in planning knee surgeries and to perform a narrative description of the latest publications on AR applications in knee surgery. Augmented reality-assisted knee surgery is an emerging set of techniques that can increase accuracy, efficiency, and safety and decrease the radiation exposure (in some surgical procedures, such as osteotomies) of other conventional methods. Initial clinical experience with AR projection based on ArUco-type artificial marker sensors has shown promising results and received positive operator feedback. Once initial clinical safety and efficacy have been demonstrated, the continued experience should be studied to validate this technology and generate further innovation in this rapidly evolving field.

Early Identification and Treatment of Trochlear Knee Dysplasia.

A shallow sulcus characterizes trochlear dysplasia (TD) of the femoral trochlea, which can lead to chronic pain or instability of the patellofemoral joint. Breech presentation at birth has been identified as a risk factor for developing this condition, which an ultrasound can identify early. Early treatment could be considered at this stage, given the potential for remodelling in these skeletally immature patients. Newborns with breech presentation at birth who meet the inclusion criteria will be enrolled and randomised in equal proportions between treatment with the Pavlik harness and observation. The primary objective is to determine the difference in the means of the sulcus angle between the two treatment arms at two months. Ours is the first study protocol to evaluate an early non-invasive treatment for TD in the newborn with breech presentation at birth using a Pavlik harness. We hypothesised that trochlear dysplasia could be reverted when identified and treated early in life with a simple harness, as it is done with developmental dysplasia of the hip.

Clinical outcome and gait analysis of ankle arthrodesis.

BACKGROUND: The purpose of our study was to describe and analyze the functional outcomes of mid-term followup patients with ankle arthrodesis. METHODS: Twenty patients who had an isolated ankle arthrodesis were followed for a mean of 3 years after surgery. We performed physical and functional examination, radiographic examination and CT scan. Each completed standardized, self-reported outcome questionnaires SF-36, AOFAS and Mazur scores. All subjects were evaluated with a kinetic and kinematic gait analysis and a plantar pressure study. RESULTS: Only one patient used a cane and seven patients required an insole to walk. We observed no relation between the scores obtained. Most of the patients showed good functional results and poor life quality scores. The joints that were significantly more degenerated were the Chopart and the subtalar joints, which were affected in 16 patients in the fused limb. The kinematic parameters showed compensatory motion in the neighboring joints and the kinetic parameters studied were similar in the arthrodesis limb and the control limb. There was no significant difference between the arthrodesis limb and the contralateral limb for plantar pressures. CONCLUSION: Although ankle arthrodesis will help to relieve pain and to improve overall function, it is considered to be a salvage procedure that causes persistent alterations in gait, with the possible development of symptomatic osteoarthritis in the other joints of the foot. Patients and treating physicians should also expect overall pain and functional limitations to increase over time.

Vertical versus horizontal suture configuration for the repair of isolated type II SLAP lesion through a single anterior portal: a randomized controlled trial.

PURPOSE: To compare the clinical and functional outcomes of the repair of an isolated type II SLAP lesion by 2 different configuration techniques (vertical v horizontal suture) through a single anterior portal. METHODS: We designed a prospective, double-blinded, randomized clinical trial. A junior orthopaedic surgeon, who made the initial diagnosis, used a 10-point visual analog scale for pain and subjective instability and the American Shoulder and Elbow Surgeons (ASES) scoring system and evaluated the range of motion. After a diagnostic arthroscopy that ascertained the presence of an isolated type II SLAP lesion, patients were randomized to receive either vertical suture configuration (group 1) or horizontal suture configuration (group 2), both through a single anterior portal. Thirty-two patients were included in the study. The mean follow-up time was 37 months. RESULTS: The mean postoperative ASES score was 91.9 in group 1 versus 95.8 in group 2 (P > .05). The differences observed from preoperative ASES score for both groups to postoperative ASES score were statistically significant. The differences observed in preoperative range of motion from the contralateral healthy shoulder and the affected shoulder in both groups were all clinically and statistically significant. Comparing the overall range of motion of the affected limb postoperatively with the range of motion of the contralateral healthy shoulder and between both groups, we found no statistically significant differences in forward flexion (P = .067), external rotation (P = .101), or internal rotation (P = .343). CONCLUSIONS: The results of this study suggest that the repair of an isolated type II SLAP lesion through a single anterior portal is clinically and functionally beneficial to patients regardless of the suture configuration performed (vertical or horizontal suture) because no differences were observed between these configurations after repair of an isolated type II SLAP lesion. LEVEL OF EVIDENCE: Level I, randomized controlled trial.

Metabolic Bone Diseases and Total Hip Arthroplasty: Preventing Complications.

Metabolic bone diseases are a diverse group of conditions characterized by abnormalities in calcium metabolism and/or bone cell physiology. These unbalanced processes can eventually lead to bony deformities and altered joint biomechanics, resulting in degenerative joint disease. Not infrequently, patients with metabolic bone diseases have restricting hip joint pain that ultimately necessitates hip arthroplasty. To minimize complications, the surgeon must consider the particular characteristics of these patients. The surgical and medical management of patients with metabolic bone diseases undergoing hip arthroplasty requires appropriate preoperative diagnosis, careful attention to the technical challenges of surgery, and strategies to maximize the long-term results of the surgical intervention, such as the use of bone anabolic and anticatabolic agents.

Atypical femoral fracture post total hip replacement in a patient with hip osteoarthritis and an ipsilateral cortical thickening.

INTRODUCTION: Atypical femoral fractures (AFF) can be present in patients with hip osteoarthritis (OA). This case highlights the opportunity to review the management of stress reactions, stress fractures and atypical femoral fractures, which depend on the activity of the fracture. CASE PRESENTATION: A 66-year-old female with a history of long-term bisphosphonate use underwent a total hip replacement for symptomatic osteoarthritis with a clinical presentation of right groin pain and radiographic signs of joint space narrowing and osteophyte formation. Radiographs before hip arthroplasty showed lateral cortical thickening in the ipsilateral femur in the subtrochanteric region. The patient developed a complete periprosthesic atypical femoral fracture a month after surgery at the level of the previously identified femoral cortical thickening. DISCUSSION: Given the high amount of elderly, osteoporotic patients presenting with groin/thigh pain undergoing hip replacement, surgeons should question them about the use of bisphosphonates in the past and look for the presence of AFF. These should receive bilateral imaging studies and a metabolic bone workup in order to define the status of the fracture and determine the appropriate management before considering any other surgical intervention.

Surgical induced models of joint degeneration in the ovine stifle: Magnetic resonance imaging and histological assessment.

BACKGROUND: The purposes of this study were to (1) validate and assess the reliability of a modified magnetic resonance semi-quantitative score (sheep Magnetic Resonance osteoarthritis Knee Score (sMOAKS)) to evaluate joint degeneration in the ovine knee and to (2) investigate whether the transection of the anterior cruciate ligament (ACL), isolated or in combination with meniscal injuries, reproduce the degenerative changes described in the meniscectomized sheep. METHODS: Twenty sheep were randomly subjected to one of the following injuries to induce osteoarthritis (OA): ACL transection (ACLt), mid-body transection of the medial meniscus, ACLt combined with complete medial meniscectomy and complete medial meniscectomy. OA assessment was performed eight weeks postoperatively with sMOAKS, Mankin and Osteoarthritis Research Society International (OARSI) histological scores. RESULTS: sMOAKS showed very good to excellent reliability (kappa=0.61 to 1.0) for the majority of features evaluated. sMOAKS revealed small differences between groups (p<0.05) being the ACLt group the most affected. We observed a strong positive correlation between the three scales in the evaluation of femoro-tibial articular cartilage (AC) (r=0.829, r=0.917, r=0.879). CONCLUSIONS: sMOAKS is a reliable semi-quantitative Magnetic Resonance (MR) scale to evaluate and quantify the effect of different OA induction lesions in the ovine knee and presents a high correlation with Mankin and OARSI scales in the evaluation of femoro-tibial AC. Although minor differences were observed between the different surgical procedures for the induction of OA, ACLt proved to be the intervention that produced the highest amount of degeneration eight weeks postoperatively. LEVEL OF EVIDENCE: II.

The Efficacy of Bisphosphonates with Core Decompression and Mesenchymal Stem Cells Compared with Bisphosphonates Alone in the Treatment of Osteonecrosis of the Hip: a Retrospective Study.

INTRODUCTION: Osteonecrosis of the femoral head (ONFH) is a devastating disease with complete collapse of the femoral head often reported in greater than 70% of patients within 3 to 4 years of diagnosis. Early intervention prior to collapse may improve the chance of success of joint preserving procedures. QUESTIONS/PURPOSES: The purpose of this study was to evaluate whether core decompression with mesenchymal stem cells combined with bisphosphonate therapy can improve the clinical outcomes and reduce the risk of hip replacement when compared to treatment with bisphosphonate therapy alone. METHODS: Between 2006 and 2014, 84 consecutive patients who were diagnosed with ONFH were identified from our institution's registry. Of these 84 patients, 49 patients (62 hips), fit inclusion/exclusion criteria. Twenty-nine patients (40 hips) were treated with bisphosphonate therapy only. Twenty patients (20 hips) were treated with bisphosphonates, core decompression, and mesenchymal stem cells. Functional outcomes were assessed using the Modified Harris Hip Score (MHHS), the visual analog score (VAS), and evaluation of support system. Clinical failure was defined as deterioration of the MHHS/VAS scores and support system used severe enough to require THR. Radiologic outcome measures included the XR and MR imaging staging of the hip. Survival analysis was performed with total hip replacement as the end point failure. Collapse was defined as progression from Ficat stage I or II to stage III and from Steinberg I, II, III to IV, V, VI. RESULTS: Failure requiring THR occurred in 21/40 (52.5%) of bisphosphonates (BP)-treated hips at a mean follow-up of 25.3 ± 11.5 months and 5/22 (22.73%) of BP + CD + MSC-treated hips at a mean follow-up of 22.7 ± 19.5 months. The median (Q1, Q3) time to collapse was 24.9 (7.4, 33.0) months in BP-treated hips and 27.3 (27.3) months in BP + CD + MSC-treated hips. There was no evidence of a difference in functional outcomes between the two treatment groups. After adjusting for baseline Ficat stage, age, and sex, an unreplaced hip treated with BP + CD + MSC had 0.42 (95% CI 0.11, 1.57) times the risk of being replaced in the next moment compared to an unreplaced hip treated with bisphosphonates only (P = 0.196). CONCLUSION: Our results demonstrate that treatment with BP alone or BP + CD + MSC can postpone the need for total hip arthroplasty (THA) in the first 24 months in patients with ONFH compared to previously reported data, but there is no statistically significant difference between the two treatment groups. Combination therapy of BP + CD + MSC may be more effective in delaying the progression of collapse in early stage ONFH. Future prospective studies are warranted to determine the efficacy of these treatment strategies in the long term.

Iliopsoas Bursa-Hip Capsule Connection Leading to Intra-abdominal Fluid Extravasation.

Intra-abdominal fluid extravasation is a rare complication of hip arthroscopy, with a reported incidence of 0.16%. Associated risk factors include recent acetabular fracture, extra-articular procedures, iliopsoas tenotomy, and high fluid pump pressure. These previously reported risk factors were not present in the 48-year-old woman reported in this article. The patient elected to undergo hip arthroscopy for mechanical hip pain that persisted for 18 months. Preoperative magnetic resonance imaging scan showed a "normal variant communication [between] the iliopsoas bursa" and the hip capsule. Postoperative examination showed a tense, distended abdomen. After extubation, the patient had severe abdominal and pleuritic chest pain. Postoperative imaging showed significant retro- and intraperitoneal fluid extravasation. Ultrasound-guided paracentesis was used to drain the intraperitoneal fluid collection, with a significant decrease in pain. The patient returned home less than 24 hours later, with no further complications. The authors believe that the preexisting connection between the hip capsule and the iliopsoas bursa allowed the arthroscopy fluid to easily track proximally within the tendon sheath, despite relatively low fluid pump pressure. Surgeons should be aware of this possible "normal variant communication," which may be considered a relative contraindication to hip arthroscopy, especially in patients with arthritic changes on preoperative imaging. This must be addressed with the patient preoperatively, with proper counseling and patient selection. If arthroscopy is pursued, the surgical and anesthesia teams must be vigilant for signs of intra-abdominal fluid extravasation and must be prepared to treat this potentially serious complication.

Current concepts on osteonecrosis of the femoral head.

It is estimated that 20000 to 30000 new patients are diagnosed with osteonecrosis annually accounting for approximately 10% of the 250000 total hip arthroplasties done annually in the United States. The lack of level 1 evidence in the literature makes it difficult to identify optimal treatment protocols to manage patients with pre-collapse avascular necrosis of the femoral head, and early intervention prior to collapse is critical to successful outcomes in joint preserving procedures. There have been a variety of traumatic and atraumatic factors that have been identified as risk factors for osteonecrosis, but the etiology and pathogenesis still remains unclear. Current osteonecrosis diagnosis is dependent upon plain anteroposterior and frog-leg lateral radiographs of the hip, followed by magnetic resonance imaging (MRI). Generally, the first radiographic changes seen by radiograph will be cystic and sclerotic changes in the femoral head. Although the diagnosis may be made by radiograph, plain radiographs are generally insufficient for early diagnosis, therefore MRI is considered the most accurate benchmark. Treatment options include pharmacologic agents such as bisphosphonates and statins, biophysical treatments, as well as joint-preserving and joint-replacing surgeries. the surgical treatment of osteonecrosis of the femoral head can be divided into two major branches: femoral head sparing procedures (FHSP) and femoral head replacement procedures (FHRP). In general, FHSP are indicated at pre-collapse stages with minimal symptoms whereas FHRP are preferred at post-collapse symptomatic stages. It is difficult to know whether any treatment modality changes the natural history of core decompression since the true natural history of core decompression has not been delineated.