Internal Brace Fixation Technique for Lisfranc Injury: A Retrospective Study.

BACKGROUND The Lisfranc ligament is crucial for maintaining the transverse and longitudinal arch of the foot. Owing to the disruption between the medial cuneiform bone and the base of the second metatarsal bone, the currently preferred fixation method remains controversial. Our fixation technique involves screwing one anchor to the medial and intermediate cuneiform bones and using the anchor to carry the ligament to bind the Lisfranc joint and first and second metatarsal joints altogether for elastic fixation. This study evaluated the clinical and functional outcomes of InternalBrace fixation for Lisfranc injury. MATERIAL AND METHODS This retrospective study included 58 patients who underwent InternalBrace fixation for Lisfranc injury between January 2019 and September 2022 by an experienced surgeon. One-way analysis of variance or t test was used. Preoperative classification was performed according to the Myerson classification with imaging data. Postoperative follow-up was performed based on intraoperative blood loss, fracture healing time, visual analog scale (VAS) score, the American Orthopedic Foot and Ankle Society (AOFAS) score, Tegner score, and complications. RESULTS Surgery was completed in all patients, and follow-up was performed. The patients' ages ranged from 19 to 62 years (average: 34.6±9.4 years). The postoperative follow-up time was 12-24 months (average: 16.9±3.0 months). The average time for fracture healing was 12.8±3.0 (10-24) weeks. The VAS, AOFAS, and Tegner scores significantly improved postoperatively (from 5.33±1.0 (3-7) to 1.24±0.57 (0-2); 28.02±6.70 (18-51) to 91.59±4.76 (82-96); and 2.40±0.67 (1-4) to 6.53±0.54 (6-7), respectively), which was statistically significant (P<0.01), and the good rate of AOFAS was 91.4%. The postoperative complications were traumatic arthritis, incision infection, and temporary dorsal foot numbness, which gradually recovered. No other rejection reactions or Lisfranc fracture/dislocations recurrence occurred during the follow-up period. CONCLUSIONS InternalBrace fixation for Lisfranc injury is beneficial for restoring Lisfranc joint stability and function and allows for early and more aggressive rehabilitation for patients, with fewer surgical complications.

Posteromedial Corner Injuries of the Knee: Imaging Findings.

The posteromedial corner (PMC) of the knee is an anatomical region formed by ligamentous structures (medial collateral ligament, posterior oblique ligament, oblique popliteal ligament), the semimembranosus tendon and its expansions, the posteromedial joint capsule, and the posterior horn of the medial meniscus. Injuries to the structures of the PMC frequently occur in acute knee trauma in association with other ligamentous or meniscal tears. The correct assessment of PMC injuries is crucial because the deficiency of these supporting structures can lead to anteromedial rotation instability or the failure of cruciate ligaments grafts. This article reviews the anatomy and biomechanics of the PMC to aid radiologists in identifying injuries potentially involving PMC components.

Demystifying the "Dark Side of the Knee": An Update on Imaging of the Posterolateral Corner.

The posterolateral corner (PLC) of the knee is a complex anatomical-functional unit that includes ligamentous and tendinous structures that are crucial for joint stability. This review discusses the intricate anatomy, biomechanics, and imaging modalities, as well as the current challenges in diagnosing PLC injuries, with an emphasis on magnetic resonance imaging (MRI). Recognizing the normal MRI anatomy is critical in identifying abnormalities and guiding effective treatment strategies. Identification of the smaller structures of the PLC, traditionally difficult to depict on imaging, may not be necessary to diagnose a clinically significant PLC injury. Injuries to the PLC, often associated with cruciate ligament tears, should be promptly identified because failure to recognize them may result in persistent instability, secondary osteoarthritis, and cruciate graft failure.

A systematic review on how to diagnose deltoid ligament injuries-are we missing a uniform standard?

BACKGROUND: Up to now, there is no convincing evidence, that surgical treatment of deltoid ligament injuries, especially in the setting of ankle fractures, does result in improved outcome. One reason could be a missing diagnostic standard. The aim of the current systematic review was to analyze the applied diagnostic strategies for acute deltoid ligament injuries in outcome studies. METHODS: MEDLINE, Scopus, Central, and EMBASE were searched through February 2022 for any original studies addressing diagnostics of acute deltoid injuries. The study was conducted per the PRISMA guidelines. The inclusion criteria were formed according to the PICOS criteria. The data assessed were study type, level of evidence, included fractures, time point and method of diagnosing deltoid ligament layers, differentiation between layers and syndesmotic injuries. RESULTS: 31 studies were included in the final analysis. Most studies (n = 28) based their decision to treat the deltoid ligament injury on radiologic findings only, with stressed radiographs (n = 18) being the most common. The radiographs were applied at one or more time points (preoperative, before ORIF, after ORIF, after ORIF and syndesmotic repair). The most frequently assessed parameter was the Medial Clear Space (MCS, n = 27) with cut-off-values considered pathological ranging between MCS > 1 mm and MCS > 6 mm. CONCLUSION: Comparing the 31 studies shows that a standardized method to diagnose deltoid ligament injuries is missing. Further research is needed to establish evidence-based guidelines on how to diagnose acute deltoid ligament injuries. TRIAL REGISTRATION: Prospero ID: CRD42022307112. CLINICAL TRIAL NUMBER: not applicable.

Arthroscopic medial patellofemoral ligament reconstruction with polyethylene suture combined with medial retinaculum plication for the treatment of acute patellar dislocation in young and middle-aged patients with a follow-up of at least 2 years.

PURPOSE: The purpose of this study was to propose a surgical technique for arthroscopic medial patellofemoral ligament (MPFL) reconstruction with polyethylene suture combined with medial retinaculum plication and to evaluate the efficacy of this surgical technique in the treatment of acute patellar dislocation. METHODS: Clinical data of patients with acute patellar dislocations treated with arthroscopic MPFL reconstruction with polyethylene tape (FiberTape) combined with medial support band compression were analyzed retrospectively from January 2018 to January 2021. The mean age of the patients was 25.15 ± 4.66 years; the mean follow-up time was 27.5 (24-36) months. Clinical evaluation consisted of apprehension test results, patellar extrapolation test results, Lysholm score, Kujala score, and IKDC score, the Patellar lateral shift distance and patellar tilt angle (PTA) measured by CT scan. RESULTS: All patients had no recurrent patellar dislocation or subluxation after surgery, and the apprehension test was negative. In all patients, the Kujala score (36.0 ± 9.9 vs. 98.2 ± 3.1), the IKDC score (48.6 ± 7.0 vs. 90.6 ± 4.4) and the Lysholm score (32.8 ± 10.4 vs. 96.7 ± 3.1) had improved at the 24-month follow up (P < 0.05). In addition, PTA was significantly lower at the 12-month follow-up and 24-giving-month follow-up compared to the preoperative period (P < 0.05, Table 2). The patellar lateral shift distance decreased from 14.94 ± 6.11 mm preoperatively to 3.00 ± 1.40 mm (12-month follow up) and 3.26 ± 1.37 mm (24-month follow up), respectively. CONCLUSION: Arthroscopic MPFL reconstruction with polyethylene suture combined with medial retinaculum plication is a safe and reliable surgical technique for the treatment of acute patellar dislocation in young and middle-aged patients. LEVEL OF EVIDENCE: Level III, Therapeutic Study.

Acute patellar dislocation: how skeletal maturity affects patterns of injury.

OBJECTIVE: The main objective of this study was to understand the role of skeletal maturity in the different patterns of osteochondral and ligamentous injuries after an acute lateral patellar dislocation. MATERIALS AND METHODS: Two radiologists independently reviewed MRIs of 212 knees performed after an acute lateral patellar dislocation to evaluate the presence of high-grade patellar osteochondral injury, femoral osteochondral injury, and medial patellofemoral ligament injury. The association of skeletal maturity (indicated by a closed distal femoral physis), age, sex, and first-time versus recurrent dislocation with each of these various lesions was analyzed using Chi-square or T test, and multivariable logistic regression with estimation of odds ratios (OR). RESULTS: Skeletal maturity was significantly associated with high-grade patellar osteochondral injury [OR=2.72 (95% CI 1.00, 7.36); p=0.049] and femoral-side MPFL tear [OR=2.34 (95% CI 1.05, 5.25); p=0.039]. Skeletal immaturity was significantly associated with patellar-side MPFL tear [OR=0.35 (95% CI 0.14, 0.90); p=0.029]. CONCLUSION: Patterns of injury to the patella and medial patellofemoral ligament vary notably between the skeletally immature and mature, and these variations may be explained by the inherent weakness of the patellar secondary physis.

Systematic review of artificial intelligence development and evaluation for MRI diagnosis of knee ligament or meniscus tears.

OBJECTIVE: The purpose of this systematic review was to summarize the results of original research studies evaluating the characteristics and performance of deep learning models for detection of knee ligament and meniscus tears on MRI. MATERIALS AND METHODS: We searched PubMed for studies published as of February 2, 2022 for original studies evaluating development and evaluation of deep learning models for MRI diagnosis of knee ligament or meniscus tears. We summarized study details according to multiple criteria including baseline article details, model creation, deep learning details, and model evaluation. RESULTS: 19 studies were included with radiology departments leading the publications in deep learning development and implementation for detecting knee injuries via MRI. Among the studies, there was a lack of standard reporting and inconsistently described development details. However, all included studies reported consistently high model performance that significantly supplemented human reader performance. CONCLUSION: From our review, we found radiology departments have been leading deep learning development for injury detection on knee MRIs. Although studies inconsistently described DL model development details, all reported high model performance, indicating great promise for DL in knee MRI analysis.

MRI of patellar stabilizers: Anatomic visibility, inter-reader reliability, and intra-reader reproducibility of primary and secondary ligament anatomy.

OBJECTIVE: To compare MRI features of medial and lateral patellar stabilizers in patients with and without patellar instability. METHODS: Retrospective study of 196 patients (mean age, 33.1 ± 18.5 years; 119 women) after diagnosis of patellar instability (cohort-1, acute patellar dislocation; cohort-2, chronic patellar maltracking) or no patellar instability (cohort-3, acute ACL rupture; cohort-4, chronic medial meniscus tear). On MRI, four medial and four lateral stabilizers were evaluated for visibility and injury by three readers independently. Inter- and intra-reader agreement was determined. RESULTS: Medial and lateral patellofemoral ligaments (MPFL and LPFL) were mostly or fully visualized in all cases (100%). Of the secondary patellar stabilizers, the medial patellotibial ligament was mostly or fully visualized in 166 cases (84.7%). Other secondary stabilizers were mostly or fully visualized in only a minority of cases (range, 0.5-32.1%). Injury scores for all four medial stabilizers were higher in patients with acute patellar dislocation than the other 3 cohorts (p < .05). Visibility inter- and intra-reader agreement was good for medial stabilizers (κ 0.61-0.78) and moderate-to-good for lateral stabilizers (κ 0.40-0.72). Injury inter- and intra-reader agreement was moderate-to-excellent for medial stabilizers (κ 0.43-0.90) and poor-to-moderate for lateral stabilizers (κ 0-0.50). CONCLUSION: The MPFL and LPFL were well visualized on MRI while the secondary stabilizers were less frequently visualized. The secondary stabilizers were more frequently visualized medially than laterally, and patellotibial ligaments were more frequently visualized compared to the other secondary stabilizers. Injury to the medial stabilizers was more common with acute patellar dislocation than with chronic patellar maltracking or other knee injuries.

Etiology and Diagnostic Challenges of Ulnar Wrist Pain in Pediatric and Adolescent Patients.

PURPOSE: Diagnosing the cause of ulnar-sided wrist pain can be difficult in the pediatric and adolescent age group. While frequently used, the diagnostic accuracy of magnetic resonance image (MRI), as compared with intraoperative arthroscopic findings, is not well-described in this population. This study aimed to determine concordance rates between magnetic resonance and arthroscopic findings depending on the specific ulnar wrist pathology. METHODS: A retrospective review was performed to identify pediatric and adolescent patients who underwent operative treatment of ulnar wrist pain between 2004 and 2021. Patients were included in the analysis if they were <18 years of age, complained of ulnar-sided wrist pain, underwent MRI of the affected wrist with an available report interpreted by a consultant radiologist, and had a diagnostic arthroscopy procedure within one year of imaging. Ulnar pathologies analyzed included triangular fibrocartilage (TFCC) tears, ulnotriquetral (UT) ligament tears, lunotriquetral ligament abnormalities, and ulnocarpal impaction. RESULTS: A total of 40 patients with a mean age of 15-years-old (range 11 to 17) were included in the analysis. Twenty-four were female, and approximately half had their dominant extremity affected. Most had a history of antecedent trauma (n = 34, 85%), but only 15/40 (38%) had a history of fracture. The mean duration of symptoms prior to presentation was six months (standard deviation, 7). The most common etiologies were Palmer 1B TFCC tears (n = 27, 68%) followed by UT split tears (n = 11, 28%). MRI overall demonstrated high specificity (82% to 94%), but low sensitivity (14% to 71%) for ulnar-sided wrist conditions. Accuracy varied between 70% and 83% depending on the specific injury. CONCLUSION: While MRI is a useful adjunct for determining the cause of ulnar wrist pathologies, findings are often discordant when compared with diagnostic arthroscopy. Surgeons should have a high degree of suspicion for TFCC-related pathology in the setting of positive provocative clinical examination despite negative MRI findings in young patients. TYPE OF STUDY/LEVEL OF EVIDENCE: Diagnostic IIb.

Postoperative Stability in Displaced Ankle Fractures With Concomitant Ligamentous Injuries.

Ankle instability, which can be attributed to either the deltoid or lateral ligamentous complex, may be both a cause and a consequence of ankle fractures. This study aimed to assess postoperative ankle instability in patients with displaced ankle fractures. A total of 54 patients with displaced ankle fractures were included. Malleolar fractures were surgically reduced and fixated, and if necessary, the syndesmosis was stabilized. Concomitant deltoid injuries were left unrepaired. Ankle stress radiographs were taken approximately 25.4 months after surgery, with a standard deviation of 20.5 months. Radiographic measurements included the tibiotalar tilt angle (TT) on varus stress view, anterior translation of the talus (AT) on the anterior drawer view, and the medial clear space (MC) and tibiotalar tilt angle on the valgus stress view. These measurements were compared between the injured and the noninjured contralateral ankle for all patients as well as in a subgroup of 19 patients with concomitant deltoid and syndesmosis injuries. There were no significant differences in Varus TT (p = .675, p = .394), AT (p = .516, p = .967), Valgus MC (p = .190, p = 0.498), and Valgus TT (p = .173, p = .442) between the injured and noninjured ankles in the whole group of patients as well as in the subgroup of patients with concomitant deltoid and syndesmosis injuries. Patients with displaced ankle fractures exhibited radiographically stable ankles postoperatively. Syndesmosis fixation without deltoid ligament repair is a viable treatment option for achieving ankle stability postoperatively in fractures with both ligament injuries.

Ankle instability in pediatric and adolescent patients diagnosed with lateral malleolus avulsion fracture: Analysis of clinical and functional outcomes of ligament injury repair surgery.

BACKGROUND: Some children and adolescents can develop persistent pain and instability following inversion injuries of the ankle. In these cases, imaging exams could reveal small bone fragments distal to the lateral malleolus. For these patients, regular conservative treatment may not be successful, requiring additional management, which can include surgical treatment. This study aimed to present the short-to-midterm functional and clinical outcomes of a series of 12 pediatric and adolescent patients who underwent ligament repair surgery due to chronic instability associated with the presence of osseous components in the lateral ligaments. METHODS: A review of 12 patients treated with surgical ligament reconstruction of the ankle was evaluated. Clinical and functional evaluations were based on comparing the Visual Analogue Scale (VAS), AOFAS ankle-hindfoot score, and residual symptoms before and after the surgical intervention. RESULTS: Before the reconstructive approach, the mean VAS was 2.41 and the mean AOFAS score was 74.16. After the procedure, the standard VAS declined to zero, and the AOFAS score was 100 in all patients. The mean follow-up was 6.33 months. CONCLUSION: The surgical approach in children and adolescents with symptomatic ankle instability due to the presence of osseous fragments after an initial inversion trauma provided adequate clinical and functional results at short-to-midterm follow-up. LEVEL OF EVIDENCE: Level IV, retrospective case series.

Ligamentoplasty in scapholunate instability: short-term results of the "all dorsal scapholunate repair" technique.

Injury to the scapholunate complex is the cause of scapholunate instability which can lead to radiocarpal and medio-carpal osteoarthritis. Several ligamentoplasty techniques have been reported for the treatment of chronic scapholunate instability before the osteoarthritis stage. The objective of this study was to assess the short-term results of an "all dorsal scapholunate repair" ligamentoplasty. We report the clinical, radiological and functional results of a retrospective study including 21 patients, operated between June 2019 and December 2020 for a stage 3 or 4 scapholunate instability according to the Garcia Elias classification. With a follow-up of 14.2 months, the pain was 0.1/10 according to the VAS at rest and 4/10 during exercise. Wrist strength was measured at 65% of the opposite side. The flexion-extension range of motion was 105°. Radiologically, there was a reduction of the diastasis and scapholunate angle. Osteolysis areas around the anchors were described in 47% of patients. The mean QuickDASH was 29.2/100, PRWE 24/100 and Mayo wrist score 67.8/100. Eighty-one percent of patients were satisfied. Seventeen patients had returned to work 5.2 months postoperatively. In the case of work-related injury, the functional scores were poorer, with a delayed return to work. This technique provides encouraging results in the short term. Most patients were improved compared to preoperative state. The work-related injury appears to be a poor prognostic factor. A longer-term study is imperative to confirm the maintenance over time of the correction of carpal malalignment and the evolution of the osteolysis areas.Level of evidence: Level IV Retrospective study.

Differences of injury characteristics of medial patellofemoral ligament in acute lateral patellar dislocation and multiligament knee injuries.

BACKGROUND: The injury characteristics of medial patellofemoral ligament (MPFL) in multiligament knee injuries (MLKIs) and the differences of injury patterns of MPFL in MLKIs and acute lateral patellar dislocation (LPD) remain unclear. PURPOSE: To explore the differences of injury characteristics of MPFL after acute LPD and MLKIs. METHODS: Magnetic resonance images were prospectively analyzed in 219 patients after acute LPD or MLKIs. Statistical analyses of the injury patterns of MPFL were performed between LPD and MLKIs. RESULTS: The incidence of partial tear and complete MPFL tear in adolescent LPD and MLKIs were 40.3% and 48.4%, and 27.9% and 16.3%, respectively. Compared with LPD, MLKIs showed lower incidence rates of partial and complete MPFL tears (both P = 0). The MLKI subgroup showed lower incidence rates of MPFL tear at the patellar insertion (PAT), femoral attachment (FEM), and multiple-site of the MPFL (COM) (9.3%, 20.9%, and 14%) when compared with the LPD subgroup (45.2%, 24.2%, and 16.1%) (all P < 0.01). The incidence of partial tear and complete MPFL tear in adult LPD and MLKIs were 41.5% and 47.2%, and 24.6% and 16.4%, respectively. Compared with LPD, MLKIs showed lower incidence rates of partial and complete MPFL tears (both P = 0). The MLKI subgroup showed lower incidence rates of MPFL tear at PAT, FEM, and COM (8.2%, 18%, and 14.8%) when compared with the LPD subgroup (20.8%, 34%, and 30.2%) (all P = 0). CONCLUSION: Compared with LPD, MPFL tears are relatively uncommon in MLKIs. Even if MPFL tears occur, partial tears and femoral-sided tears are relatively more common.

Reconstruction of the interosseous talocalcaneal ligament using allograft for subtalar joint stabilization is effective.

PURPOSE: The aim of this study was to assess the biomechanical effects of subtalar ligament injury and reconstruction on stability of the subtalar joint in all three spatial planes. METHODS: Fifteen fresh frozen cadaveric legs were used, with transfixed tibiotalar joints to isolate motion to the subtalar joint. An arthrometer fixed to the lateral aspect of the calcaneus measured angular displacement in all three spatial planes on the inversion and eversion stress tests. Stress manoeuvres were tested with the intact joint, and then repeated after sequentially sectioning the inferior extensor retinaculum (IER), cervical ligament (CL), interosseous talocalcaneal ligament (ITCL), arthroscopic graft reconstruction of the ITCL, and sectioning of the calcaneo-fibular ligament (CFL). RESULTS: Sectioning the ITCL significantly increased angular displacement upon inversion and eversion in the coronal and sagittal planes. Reconstruction of the ITCL significantly improved angular stability against eversion in the axial and sagittal planes, and against inversion in the axial and coronal planes, at the zero time point after reconstruction. After sectioning the CFL, resistance to eversion decreased significantly in all three planes. CONCLUSION: Progressive injury of ligamentous stabilisers, particularly the ITCL, led to increasing angular displacement of the subtalar joint measured with the inversion and eversion stress tests, used in clinical practice. Reconstruction of the ITCL using tendon graft significantly stabilised the subtalar joint in the axial and sagittal planes against eversion and in the axial and coronal planes against inversion, immediately after surgery.

Patellofemoral articular cartilage damage is associated with poorer patient-reported outcomes following isolated medial patellofemoral ligament reconstruction.

PURPOSE: The purpose of this study was to investigate the impact of articular cartilage damage on outcomes following medial patellofemoral ligament (MPFL) reconstruction. METHODS: Record review identified 160 patients who underwent isolated MPFL reconstruction at a single institution between 2008 and 2016. Patient demographics, patellofemoral articular cartilage status at surgery, and patient anatomical measures from imaging were obtained via chart review. Patients were contacted and outcomes assessed through collection of Norwich Patellar Instability (NPI) score, Knee injury and Osteoarthritis Outcome Score (KOOS), and Marx activity score as well as an assessment for recurrent patellar dislocation. Outcomes of patients with grade 0-II patellofemoral cartilage damage were compared to those of patients with grade III-IV cartilage damage. RESULTS: One hundred twenty-two patients (76%) with a minimum of one year follow-up were contacted at a mean of 4.8 years post-operatively. A total of 63 patients (52%) had grade III or IV patellofemoral chondral damage at the time of surgery. The majority of the defects was on the medial patella (46 patients-72%) and the mean patellar defect size was 2.8 cm2. Among 93 patients who completed patient-reported outcome scores, the 52 with grade III or IV chondral damage reported a significantly poorer KOOS Quality of Life than the 44 patients with grade 0 to II chondral damage (p = 0.041), controlling for patient age, sex, BMI, and anatomical factors. CONCLUSION: Patients with grade III or IV articular cartilage damage of the patellofemoral joint at the time of MPFL reconstruction demonstrated poorer KOOS knee-related quality of life than patients without grade III or IV articular cartilage damage at a mean of 4.8 years following isolated MPFL reconstruction. LEVEL OF EVIDENCE: Level II.

Morphology of the Radial Attachment of the Radioulnar Ligament and Surrounding Landmarks.

PURPOSE: The triangular fibrocartilage complex (TFCC) is composed of dorsal and palmar radioulnar ligaments (RULs). A common injury pattern of the RUL is the avulsion of the ulnar insertion, which can be treated by arthroscopic or open repair. Although the general method of TFCC reconstruction is a tendon graft with a bone tunnel, detailed information regarding the radial attachment of the RUL is unclear. This study aimed to clarify the morphology of the radial attachments of the palmar radioulnar ligament (PRUL), dorsal radioulnar ligament (DRUL), and short radiolunate ligament (SRL) using three-dimensional imaging. METHODS: A total of 29 upper limbs (16 formalin-fixed and 13 embalmed by Thiel's embalming method) of Japanese cadavers were used. After gross observation, we marked the attachments of the PRUL, DRUL, and SRL using 0.7-mm diameter pins. We created three-dimensional images of the radius, outlining the PRUL, DRUL, and SRL attachments. The software application calculated the centers of the PRUL and DRUL attachments. RESULTS: The PRUL attachment was horizontally shaped. The center of the PRUL was 1.5 mm proximal and 5.8 mm radial to the tip of the palmar pyramid formed by the palmar cortex and the radioulnar and radiocarpal joint surfaces. The DRUL attachment was vertically shaped. The center of the DRUL was 2.0 mm proximal and 1.7 mm radial from the tip of the dorsal pyramid formed by the dorsal cortex and the radioulnar and radiocarpal joint surfaces. The length of the SRL was 9.2 mm. The SRL and PRUL were strongly conjoined. CONCLUSIONS: The anatomical center on the RUL attachment of the radius can be determined from osseous landmarks. CLINICAL RELEVANCE: The findings of this study contribute to the understanding of RUL attachment to the distal radius and may assist surgeons in performing anatomical reconstruction of TFCC.

Scapholunate Instability: Diagnosis and Management - Classification and Treatment Considerations - Part 2.

Intervention for scapholunate instability is aimed at halting the degenerative process by restoring ligament integrity and normalizing carpal kinematics. Part 1 of this Current Concepts article reviewed the anatomy, kinematics, and biomechanical properties of the scapholunate ligament as well as its critical stabilizers. In this section, we provide a foundation for understanding the spectrum of scapholunate ligament instability and incorporate meaningful new anatomical insights that influence treatment considerations. These updates clarify the importance of the critical stabilizers of the scapholunate interval, ligament-specific considerations in scapholunate ligament reconstruction, and the risks of ligament disinsertion when surgically exposing the dorsal wrist. We propose a ligament-based treatment algorithm based on the stage of injury, degree and nature of ligament damage, and presence of arthritic changes.

Scapholunate Instability: Diagnosis and Management - Anatomy, Kinematics, and Clinical Assessment - Part I.

Injuries to the scapholunate joint are the most frequent cause of carpal instability. The sequelae of these injuries account for considerable morbidity, and if left untreated, may lead to scapholunate advanced collapse and progressive deterioration of the carpus. Rupture of the scapholunate interosseous ligament and its critical stabilizers causes dyssynchronous motion between the scaphoid and lunate. Additional ligament injury or attenuation leads to rotary subluxation of the scaphoid and increased scapholunate gap. Intervention for scapholunate instability is aimed at halting the degenerative process by restoring ligament integrity and normalizing carpal kinematics. In the first section of this review, we discuss the anatomy, kinematics, and biomechanical properties of the scapholunate ligament as well as its critical ligament stabilizers. We provide a foundation for understanding the spectrum of scapholunate ligament instability and incorporate meaningful new anatomical insights that influence treatment considerations. The purpose is to provide an update regarding the anatomy of the scapholunate ligament complex, importance of the critical ligament stabilizers of the proximal carpal row, introduction of safe technique to surgically expose the scaphoid and lunate, as well as pathoanatomy as it pertains to the treatment of scapholunate dissociation. In the second section of this review, we propose a novel ligament-based treatment algorithm based on the stage of injury, degree and nature of ligament damage, and presence of arthritic changes.

Subject-specific computational modeling of acromioclavicular and coracoclavicular ligaments.

BACKGROUND: Disruption of the acromioclavicular joint is a common injury. Despite the different surgical procedures described for treating this injury, complications such as loss of reduction and failure of fixation remain unacceptably high. We developed a computer model of the acromioclavicular joint to better understand the biomechanical contributions of the ligaments that are typically injured. METHODS: Six fresh frozen human cadaveric shoulders were tested on an AMTI VIVO 6-degree of freedom test platform to measure force-displacement in inferior translation, anteroposterior translation, and internal rotation before and after sequentially transecting the coracoclavicular and acromioclavicular ligaments. These data were used to construct computer models of each specimen. Three-dimensional computed tomographic scans were used to generate a rigid-body dynamics model using the AnyBody Modeling System. The scapula and clavicle were connected by the acromioclavicular joint capsule, the conoid ligament, and the trapezoid ligament. Subject-specific ligament properties were calculated by matching computer predictions to experimental force-displacement data. RESULTS: The calculated free lengths of the conoid, trapezoid, and acromioclavicular ligaments were 13.5 (±3.2), 11.8 (±2.4), and 11.0 (±2.7) mm, respectively. The calculated stiffnesses of the conoid, trapezoid, and acromioclavicular ligaments were 34.3 (±6.3), 28.4 (±3.2), and 33.8 (±8.2) N/mm, respectively. Root mean square deviation (RMSD) of predicted force-displacement curves relative to experimental force-displacement curves (during inferior and anteroposterior translation) was less than 1 mm. For validation of subject-specific models, after ligament properties were calculated, the RMSD of the predicted torque over 15° of internal rotation was 12% of maximum rotational torque (average for 6 specimens). DISCUSSION AND CONCLUSION: Acromioclavicular disruption results in multidirectional instability, which requires careful consideration of the individual contributions of the injured ligaments. In addition, variations in patient anatomy can significantly affect the biomechanical stability of the reconstruction. Subject-specific models can enhance our understanding of the individual and collective biomechanical contributions of the injured soft tissues to the multiaxial stability of the acromioclavicular joint. These models may also be useful for analyzing and assessing biomechanical stability after various types of surgical reconstruction.

Stability, deformity, and fixation of the floating shoulder: a cadaveric biomechanical study.

BACKGROUND: Floating shoulder injuries cause instability and deformity due to disruptions of the scapula, clavicle, and superior shoulder suspensory complex ligaments (SSSC). Resulting deformity of the glenopolar angle (GPA) has not previously been established, nor has the impact on stability and deformity when surgical fixation is performed. This study sought to quantify stability and deformity for multiple injury patterns and the improvement to these parameters provided by clavicle and coracoclavicular (CC) ligament fixation. METHODS: Fourteen cadaveric specimen upper extremities were used, which included the entire upper extremity, scapula, clavicle, and cranial-most ribs. After being mounted upright, a scapular neck fracture was created, followed by either a midshaft clavicle fracture or sectioning of the acromioclavicular and coracoacromial ligaments. Subsequent sectioning of the other structure(s) followed by the CC ligaments was then performed. In all specimens, the clavicle was then plated, followed by a CC ligament repair. At each step, a radiograph in the AP plane of the scapula was taken to measure GPA and displacement of the glenoid fragment using radiopaque markers placed in the scapula. These radiographs were taken both unloaded and with a 100-N applied medializing force. RESULTS: When evaluating deformity related to sectioning, the GPA was reduced when the CC ligaments were sectioned compared to an isolated scapula fracture (P = .022) and compared to a combined scapula and clavicle fracture (P = .037). For stability, displacement with a 100-N force was significantly increased when the CC ligaments were sectioned compared to an isolated scapula fracture (P = .027). In cases of an ipsilateral scapula neck and clavicle fracture with intact ligaments, fixation of the clavicle alone provided a statistically significant improvement in the GPA (P = .002); but not in reduction of displacement (P = .061). In cases of an ipsilateral scapula neck and clavicle fracture with concomitant disruption of the coracoacromial, acromioclavicular, and CC ligaments, the GPA was improved by clavicle fixation (P < .001) and increasingly so by subsequent CC ligament repair (P < .001). Displacement was also improved in these 2 states (P < .001, P = .008, respectively). DISCUSSION: This biomechanical study confirmed the importance of the acromioclavicular, coracoacromial, and CC ligaments in conferring stability in SSSC injuries. Disruption of the CC ligaments created significant deformity of the GPA and instability with a medializing force. Clinical treatment should consider the integrity of these ligaments and their repair in conjunction with clavicle fixation, knowing that this combination should restore a biomechanical state equivalent to an isolated scapula fracture.