Computational comparison of medializing tibial tubercle osteotomy and trochleoplasty in patients with trochlear dysplasia.

Medial patellofemoral ligament reconstruction (MPFLR) has emerged as the procedure of choice for recurrent patellar dislocation. This addresses soft tissue injury but does not address underlying anatomic factors, including trochlear dysplasia, that are commonly present and increase risk of dislocation. Quantification of the stability offered by other surgical interventions, namely, medializing tibial tubercle osteotomy (mTTO) and trochleoplasty, with and without MPFLR, may provide insight for surgical choices in patients with trochlear dysplasia. We developed subject-specific finite element models based on magnetic resonance scans from a cohort of 20 patients with trochlear dysplasia and recurrent patellar dislocation. The objectives of this study were (1) to compare patella stability after mTTO and trochleoplasty procedures; (2) to evaluate whether it is necessary to perform an MPFLR in combination with the mTTO or trocheoplasty procedure; and (3) to quantify the robustness of patellar stability to variability in knee kinematics. Trochleoplasty performed better than mTTO at stabilizing the patella between 5° and 30° flexion. For both mTTO and trochleoplasty procedures, it was beneficial to also perform MPFLR-inclusion of MPFLR halved the magnitude of patellar laxity predicted in the simulations. Simulations that did not include any medial patellofemoral ligament restraint were also more sensitive to variation in tibiofemoral internal-external kinematics.

Empty Sunrise Sign: An Arthroscopic Finding in Recurrent Patellar Dislocation.

Patellar dislocation is a relatively common knee injury and can be challenging to diagnose. We describe an arthroscopic finding we noted in recurrent patellar dislocation. Arthroscopic photos were evaluated from 50 knees with a history patellar dislocation and 100 control patients. We quantified the amount of patellar subluxation seen on a single arthroscopic view and coined it Empty Sunrise Sign if the patella did not overlap the trochlea. Empty Sunrise Sign was found in 82% of 50 cases with recurrent patellar dislocation and none of the 100 control cases. The finding was 100% specific for identifying a recurrent patellar dislocator. High interobserver agreement was noted. Empty Sunrise Sign suggests significant capsular laxity. This may need to be considered in the surgical treatment of recurrent patellar dislocation.

Computational approach to correcting joint instability in patients with recurrent patellar dislocation.

Patellar dislocation is a debilitating injury common in active adolescents and young adults. Conservative treatment after initial dislocation is often recommended, but almost half of these patients continue to suffer from recurrent dislocation. The objective of this study was to compare preoperative patellofemoral joint stability with stability after a series of simulated procedures, including restorative surgery to correct to pre-injury state, generic tibial tubercle osteotomy, patient-specific reconstructive surgery to correct anatomic abnormality, less invasive patient-specific surgery, and equivalent healthy controls. Three-dimensional, subject-specific finite element models of the patellofemoral joint were developed for 28 patients with recurrent patellar dislocation. A 50 N lateral load was applied to the patella to assess the lateral stability of the patellofemoral joint at 10° intervals from 0° to 40° flexion. Medial patellofemoral ligament reconstruction, along with reconstructive procedures to correct anatomic abnormality were simulated. Of all the simulations performed, the healthy equivalent control models showed the least patellar internal-external rotation, medial-lateral translation, and medial patellofemoral ligament restraining load during lateral loading tests. Isolated restorative medial patellofemoral ligament reconstruction was the surgery that resulted in the most patellar internal-external rotation, medial-lateral translation, and medial patellofemoral ligament reaction force across all flexion angles. Patient-specific reconstruction to correct anatomic abnormality was the only surgical group to have non-significantly different results compared with the healthy equivalent control group across all joint stability metrics evaluated. Statement of clinical significance: This study suggests patient-specific reconstructive surgery that corrects underlying anatomic abnormalities best reproduces the joint stability of an equivalent healthy control when compared with the pre-injury state, generic tibial tubercle osteotomy, and less invasive patient-specific surgery. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:768-776, 2020.

Quadriceps Tendon Autograft Medial Patellofemoral Ligament Reconstruction.

PURPOSE: Critically evaluate the published literature related to quadriceps tendon (QT) medial patellofemoral ligament (MPFL) reconstruction. RECENT FINDINGS: Hamstring tendon (HT) MPFL reconstruction techniques have been shown to successfully restore patella stability, but complications including patella fracture are reported. Quadriceps tendon (QT) reconstruction techniques with an intact graft pedicle on the patella side have the advantage that patella bone tunnel drilling and fixation are no longer needed, reducing risk of patella fracture. Several QT MPFL reconstruction techniques, including minimally invasive surgical (MIS) approaches, have been published with promising clinical results and fewer complications than with HT techniques. Parallel laboratory studies have shown macroscopic anatomy and biomechanical properties of QT are more similar to native MPFL than hamstring (HS) HT, suggesting QT may more accurately restore native joint kinematics. Quadriceps tendon MPFL reconstruction, via both open and MIS techniques, have promising clinical results and offer valuable alternatives to HS grafts for primary and revision MPFL reconstruction in both children and adults.

Quality assessment of radiological measurements of trochlear dysplasia; a literature review.

PURPOSE: To make a systematic review with quality assessments of the known measurements used to describe trochlear dysplasia. METHODS: A systematic literature search was conducted in the databases PubMed and Embase using the search string "trochlea dysplasia OR trochlear dysplasia". Papers were screened for their relevance based on predefined parameters, and all measurements showing a statistical association between trochlear dysplasia and patellar instability were presented. Four experts evaluated the quality of the measures using a purpose-made quality scale. RESULTS: The search generated 600 papers of which eight were chosen for review. Thirty-three unique measurements were identified and described in order of their date of publication. The lateral trochlea inclination was rated highest by the expert panel. The crossing sign, the trochlea bump, the TT-TG distance, the trochlea depth and the ventral trochlea prominence also had high ratings. CONCLUSION: Thirty-three unique measurements were identified with the lateral trochlea inclination as the highest rated measurement by the expert panel, and it is recommended for use in assessment of trochlear dysplasia. The crossing sign, the trochlea bump, the TT-TG, the trochlea depth and the ventral trochlea prominence were also rated well and can be recommended for use. LEVEL OF EVIDENCE: V.

The Anatomy of the Medial Patellofemoral Ligament.

Recurrent patellar dislocation is observed in many patients treated nonoperatively following primary dislocation. Injury to the medial patellofemoral ligament (MPFL) is reported in the majority of patients following dislocation. There is an increased interest in repair or reconstruction of the MPFL for patients experiencing recurrent instability. The femoral attachment of the MPFL is critical in determining graft behavior following reconstruction. The femoral attachment can be determined by referencing local anatomy, fluoroscopic imaging or on the basis of desired graft-length changes. This article reviews the anatomy of the MPFL, with a focus on its femoral insertion site as it pertains to anatomic, isometric, and anisometric reconstruction. [Orthopedics. 2017; 40(4):e583-e588.].

Computational analysis of factors contributing to patellar dislocation.

Treatment for an initial incidence of patellar dislocation is usually conservative management; however, almost half of patients experience a subsequent, or multiple, dislocation(s). Patients often undergo multiple procedures which fail to treat the underlying anatomic abnormalities. The objective of this study was to evaluate interactions between key predisposing anatomic factors to patellar dislocation and identify combinations of abnormal factors which increase the risk of recurrent lateral dislocation. Four factors associated with lateral patellar dislocation were identified (sulcus angle, Insall-Salvati ratio, tibial tubercle-trochlear groove distance, and femoral anteversion). A finite element model of the patellofemoral joint was developed and parameterized so that a value for each factor could be applied and the model geometry/alignment would be modified accordingly. 100 combinations of the four factors were generated in separate computational simulations and resulting kinematics and forces of the patellofemoral joint were recorded. Sulcus angle was the most impactful factor on constraint. Multiple abnormal factors were generally required to produce the extremes of patellar alignment observed in this analysis. Understanding the underlying anatomic factors, and their effect on joint mechanics, for patients with recurrent lateral patellar dislocation will aid in determining optimal treatment pathways on a patient-specific basis.

The prevalence and combined prevalences of anatomic factors associated with recurrent patellar dislocation: a magnetic resonance imaging study.

BACKGROUND: Anatomic factors, including patella alta, increased tibial tubercle-trochlear groove (TT-TG) distance, rotational deformities, and trochlear dysplasia, are associated with dislocation of the patella. Identifying the presence of these anatomic factors both in isolation and in combination may influence treatment in patients with patellar dislocation. PURPOSE: The aim of this study was to compare the prevalence and combined prevalences of these anatomic factors using magnetic resonance imaging in a group of patients with and without histories of recurrent dislocation of the patella. STUDY DESIGN: Case-control study; Level of evidence, 3. METHODS: The prevalence and combined prevalences of patella alta, increased TT-TG distance, rotational deformity, and trochlear dysplasia on magnetic resonance imaging were reported and compared in 60 patients (60 knees) with and 120 patients (120 knees) without histories of recurrent patellar dislocation. RESULTS: Patients with recurrent patellar dislocation possessed higher rates of patella alta (60.0% vs. 20.8%), increased TT-TG distance (42.0% vs. 3.2%), rotational deformity (26.7% vs. 2.5%), and trochlear dysplasia (68.3% vs. 5.8%) compared with patients without histories of patellar dislocation. Multiple anatomic factors were identified in 58.3% of patients (35/60) with recurrent dislocation compared with only 1.7% of controls (2/120). CONCLUSION: Recurrent patellar dislocation is associated with an increased prevalence of patella alta, increased TT-TG distance, rotational deformity, and trochlear dysplasia compared with patients with no histories of patellar dislocation. Multiple anatomic factors were identified in the majority of patients with recurrent dislocation. Further research may identify which factors play a greater role in patellar stability and may allow physicians to predict which first-time dislocation patients are more likely to sustain recurrence.

Safety of bilateral total knee arthroplasty in morbidly obese patients.

There has been an increase in the prevalence of morbid obesity and the demand for total knee arthroplasty (TKA). Physicians must help patients with bilateral knee arthritis to make informed decisions regarding whether to undergo staged, sequential, or simultaneous TKA. The purpose of this study was to evaluate the perioperative complications of 2-team simultaneous bilateral TKA in the morbidly obese. The authors performed a retrospective review of the records at a single tertiary hospital from 1997 to 2007 and identified 35 morbidly obese (body mass index [BMI] greater than 40 kg/m(2)) patients who had undergone unilateral TKA, as well as 42 morbidly obese and 79 nonobese (BMI less than 30 kg/m(2)) patients who underwent simultaneous bilateral TKA. Clinical, operative, and postoperative variables and complication rates were recorded. Clinical variables were similar between the morbidly obese TKA patients. The bilateral group had significantly increased operative times (132.4 vs 115.5 minutes; P<.01), intravenous fluids (2556.1 vs 2114.7 mL; P=.03), percentage transfused (64.2% vs 11.4%; P<.01), days in the hospital (3.6 vs 3.2 days; P=.03), and discharge rates to rehabilitation facility (72.7% vs 48.6%; P=.01). Major and minor complications were few and comparable, with the need for manipulation under anesthesia in unilateral TKA (11.4%; P=.04) as the only significant difference between groups, including when comparing bilateral nonobese TKAs with bilateral morbidly obese TKAs. The authors feel that morbidly obese patients may undergo 2-team simultaneous bilateral TKA after careful discussion regarding some of the differences in short-term outcomes.

Medial collateral ligament recession for chronic medial knee laxity.

The medial collateral ligament (MCL) is the primary restraint to valgus stress of the knee. Although the MCL has demonstrated an ability to reliably heal with conservative management, chronic medial instability has been well described following an isolated MCL injury or in combination with an anterior cruciate ligament (ACL) tear. When the MCL heals with persistent medial laxity surgical treatment may be necessary to prevent chronic medial instability and valgus overload of a reconstructed cruciate ligament. We present a simple technique for MCL recession that can be used for isolated MCL laxity as well as in chronic ACL/MCL knee injuries. This technique allows for secure fixation with bone-to-bone healing, avoids donor-site morbidity, maintains relative MCL isometry, and can be performed through a modest incision.

Perioperative morbidity and mortality of 2-team simultaneous bilateral total knee arthroplasty.

Total knee arthroplasty (TKA) has a well-established track record for relieving pain associated with arthritis of the knee joint. The total rate of bilateral TKA has doubled over the past 2 decades, and the rate in women has tripled over that same time period. In patients with bilateral knee arthritis, a decision must be made whether to operate at 2 different settings (staged), a single setting with 1 surgeon (sequential simultaneous), or a single setting with 2 surgeons (2-team simultaneous). The purpose of this study was to examine the perioperative morbidity and mortality of 2-team simultaneous bilateral TKA. Two hundred twenty-seven consecutive 2-team simultaneous bilateral TKA and 216 consecutive unilateral TKA patients were reviewed. Major (deep infection, death, cerebrovascular accident, myocardial infarction, pulmonary embolism, revision within the 1-year follow-up) and minor (all other) complications were compared. No deaths occurred, and the major and minor complication rates were not statistically significantly different between the 2 groups, but a trend toward higher rates of both major and minor complications existed in the bilateral TKA group. Two-team simultaneous bilateral TKA offers the potential benefits of decreased overall recovery time, decreased overall cost, decreased number of anesthetic administrations, and simultaneous correction of significant deformity. It remains an appropriate option in select patients.

Lower extremity bypass graft occlusion after intramedullary fixation of intertrochanteric hip fracture on a fracture table.

This article presents a case of a 90-year-old woman who previously underwent a common femoral to anterior tibial artery bypass grafting with a Gore-Tex graft (Gore Medical, Flagstaff, Arizona). She subsequently sustained an ipsilateral intertrochanteric hip fracture after a mechanical fall and underwent internal fixation with an intramedullary nail using a fracture table. In the immediate postoperative period, she developed limb-threatening ischemia in her leg due to graft thrombosis. The patient underwent a successful thrombectomy and embolectomy. However, she subsequently developed nonhealing ulcers to this extremity over the course of weeks, requiring surgical debridement. Gangrene ensued and she underwent a below-the-knee amputation.Complications from the use of fracture tables have been described for perineal soft tissue injury, leg malrotation or malalignment, neurologic injury, and iatrogenic compartment syndrome of the healthy leg. Arterial complications after intramedullary fixation of femur fractures are rare and may be caused by direct arterial trauma during placement of the locking screws through the intramedullary nail. This article is the first, to our knowledge, to describe an occlusion of a lower extremity bypass graft after intramedullary fixation on a fracture table. Surgeons should be aware of potential limb threatening ischemia in patients with peripheral vascular disease, especially in those with prior lower extremity bypass grafts. Proper preoperative counseling should be given to these patients when using fracture tables during hip fracture surgery.

Perioperative safety of two-team simultaneous bilateral total knee arthroplasty in the obese patient.

BACKGROUND: Although the rates of perioperative morbidity and mortality with simultaneous bilateral total knee arthroplasty remain a concern, multiple studies have shown the procedure to be safe in selected patient populations. Evidence also remains mixed regarding the outcomes of total knee arthroplasty in obese patients. The purpose of this paper is to compare the rates of perioperative morbidity and mortality in consecutive obese patients undergoing two-team simultaneous bilateral total knee arthroplasty and unilateral total knee arthroplasty. METHODS: The records on all two-team simultaneous total knee arthroplasties and unilateral total knee arthroplasties from October 1997 to December 2007 were reviewed. A total of 151 patients with a body mass index (BMI) >30 undergoing two-team simultaneous total knee arthroplasty and 148 patients with a BMI >30 undergoing unilateral total knee arthroplasty were retrospectively reviewed and analyzed to determine perioperative morbidity and mortality as well as one-year mortality rates. RESULTS: Preoperative patient characteristics did not show any significant differences between groups. The simultaneous bilateral group had significantly longer operative times (127.4 versus 112.7 minutes, p < 0.01), estimated blood loss (176.7 versus 111.6 mL, p = 0.01), percentage of patients requiring blood transfusion (64.9% versus 13.9%, p < 0.01), length of hospital stay (3.72 versus 3.30 days, p < 0.01), and percentage of patients requiring extended care facility usage at discharge (63.6% versus 27.8%, p < 0.01). No significant difference between unilateral and bilateral groups was seen in regards to total complication rate, major or minor complication subgroup rate, or any particular complication noted. Doubling the variables in the unilateral group for a staged total knee arthroplasty scenario did create significant increases over the simultaneous data in almost every data category. CONCLUSIONS: Two-team simultaneous total knee arthroplasty appears to be safe in obese patients, with similar complication rates as compared to unilateral procedures. Two-team simultaneous total knee arthroplasty also appears to have potential benefits over a staged procedure in the obese patient, although more study is required regarding this topic.

Excursion of oscillating saw blades in total knee arthroplasty.

Intraoperative disruption of the medial collateral ligament during total knee arthroplasty is an uncommon complication that can be avoided by retractor placement as well as by careful cutting of the femur and tibia. This study evaluated the excursion of a small and large oscillating saw blade and compared the data against the widths of both the medial and lateral femoral condyle cuts. We discovered that the large saw blade had a statistically significantly larger excursion than the medial and lateral condyle width in women, as well as the lateral condyle width in men. The small saw blade excursion did not exceed any condyle width. We conclude that the smaller saw blade should be considered when making these cuts because the excursion of the large saw blade may exceed the width of cut needed and endanger important structures such as collateral ligaments.

The medial patellofemoral ligament.

There has been substantial progress in our understanding of the medial patellofemoral ligament during the past 10 years. This structure is the primary static soft-tissue restraint to lateral patellar displacement. Substantial alteration of normal patellar tracking occurs after sectioning of the ligament. Clinical studies have demonstrated the medial patellofemoral ligament is disrupted during acute patellar dislocation. Recently, several medial patellofemoral ligament-based procedures have been developed for the treatment of patellar instability with good early results. However, further studies are needed to define the exact role of these procedures in the treatment of patellofemoral instability.

Reconstruction of the medial patellofemoral ligament using a quadriceps tendon graft: a case series.

UNLABELLED: This study assessed medial patellofemoral ligament reconstruction using a partial-thickness quadriceps tendon graft in 14 knees in 13 patients. Nine patients were available for follow-up after a minimum of 24 months. Final patient evaluation was performed an average of 42 months postoperatively (range, 28-65 months). Primary outcome measure was occurrence of patellar dislocation postoperatively, and outcomes were quantified using the Kujala questionnaire and Crosby and Insall criteria. Postoperatively, no patient reported patellar dislocation. Using Crosby and Insall criteria, good or excellent results were achieved in 100% of patients. Mean Kujala score was 91.9. Postoperatively, all patients reported their knee was improved. These findings indicate medial patellofemoral ligament reconstruction with a quadriceps tendon graft is effective in preventing patellar dislocation and improving quality of life. However, patients should be counseled this procedure is indicated primarily for the treatment of recurrent instability, and postoperative relief of anterior knee pain is inconsistent. LEVEL OF EVIDENCE: Level IV, Case Series.

The sartorial branch of the saphenous nerve: its anatomy at the joint line of the knee.

PURPOSE: Injury to the saphenous nerve accounts for the majority of neurovascular complications during arthroscopic meniscal repairs. Although the anatomy of the infrapatellar branch has been studied, the location of the sartorial branch at the level of the joint line has not been defined adequately. The purpose of this study was to define the location of the sartorial branch in relation to surrounding structures at the level of the knee joint/meniscus. TYPE OF STUDY: Cadaveric anatomic study and imaging study. METHODS: We dissected 42 cadaveric knees and studied an additional 100 knees with axial magnetic resonance imaging (MRI). We measured distances from the nerve to adjacent structures and evaluated and graphically recorded 2-dimensional axial relationships. Dissections and MRIs were performed with the knee in full extension. RESULTS: In the dissected cadaveric knees, the distance from the nerve to the anterior border of the sartorius averaged 16.0 mm, with 90% greater than 10.0 mm. The nerve was extrafascial at the joint line in only 43% of the specimens. Axial MRI examinations found the average distance to the anterior border of the sartorius to be 16.5 mm, with 82% greater than 1.0 cm. The average distance to the gracilis tendon was 9.4 mm; 91% were within 1.0 cm and 51% within 5 mm. The average distance to the semitendinosus was 14.9 mm; none was within 5 mm. The nerve was never posterior or lateral to the semitendinosus, never posterolateral or lateral to the gracilis, and was anterior to the sartorius in only 3% of knees. CONCLUSIONS: This study describes the most common location of the sartorial branch of the saphenous nerve and the potential variability that may be encountered. CLINICAL RELEVANCE: Understanding the anatomy of the sartorial branch at the level of the joint line and its relationships to surrounding structures will help to minimize the risk of injury to the nerve during common surgical procedures at the posteromedial corner of the knee.

A simple technique for reconstruction of the medial patellofemoral ligament using a quadriceps tendon graft.

Numerous surgical procedures have been described for the treatment of recurrent patellar dislocation. Studies have shown that the primary pathoanatomy associated with lateral patellar dislocation is injury to the medial patellofemoral ligament (MPFL), which is the major soft-tissue restraint to lateral patellar translation. Recently, various procedures have been described that address the medial ligamentous injury inherent to lateral patellar dislocation. We present a simple technique for MPFL reconstruction using a quadriceps tendon graft.

Minimally invasive "crescentic" imbrication of the medial patellofemoral ligament for chronic patellar subluxation.

Chronic patellar subluxation is one of the many causes of anterior knee pain. Nonoperative management of this disorder is successful in many patients, but surgical intervention may be necessary for refractory cases. We present a surgical technique for chronic patellar subluxation that is minimally invasive and is focused specifically on the medial patellofemoral ligament.