Intraoperative Near-infrared Fluorescence (NIR) Imaging With Indocyanine Green (ICG) Can Identify Bone and Soft Tissue Sarcomas Which May Provide Guidance for Oncological Resection.

BACKGROUND: Complete excision of sarcomas to maximize function without compromising the oncological outcome can be challenging. The aim of this study was to investigate the feasibility and potential drawbacks of near-infrared (NIR) fluorescence imaging with indocyanine green during resection of bone and soft tissue sarcomas. METHODS: Eleven patients with high-grade sarcomas were enrolled in the study. All patients received intravenous indocyanine green (75 mg) between 16 and 24 hours before the resection. Sarcomas were resected under NIR guidance and specimens were sent for routine histopathological analysis. RESULTS: Majority of treatment naive tumors demonstrated fluorescence. There were no adverse events from the indocyanine green administration. In 3 cases, the fluorescence was reported by the surgeon to have been of definite guidance leading to further tissue resection to improve the margin. CONCLUSION: This is the first report of NIR fluorescence guidance in the setting of open sarcoma surgery. The technique is acceptable to patients and surgeons and was able to guide resection. Multicenter studies are required to assess the utility of this technique in a large cohort of patients with regards to quantification of fluorescence, resection guidance, and longer follow-up period.

Internal femoral component rotation adversely influences load transfer in total knee arthroplasty: a cadaveric navigated study using the Verasense device.

PURPOSE AND HYPOTHESIS: Correct femoral component rotation at knee arthroplasty influences patellar tracking and may determine function at extremes of movement. Additionally, such malrotation may deleteriously influence flexion/extension gap geometry and soft tissue balancing kinematics. Little is known about the effect of subtle rotational change upon load transfer across the tibiofemoral articulation. Our null hypothesis was that femoral component rotation would not influence load across this joint in predictable manner. METHODS: A cadaveric study was performed to examine load transfer using the orthosensor device, respecting laxity patterns in 6° of motion, to examine load across the medial and lateral compartments across a full arc of motion. Mixed-effect modelling allowed for quantification of the effect upon load with internal and external femoral component rotation in relation to a datum in a modern single-radius cruciate-retaining primary knee design. RESULTS: No significant change in maximal laxity was found between different femoral rotational states. Internal rotation of the femoral component resulted in significant increase in medial compartment load transfer for knee flexion including and beyond 60°. External rotation of the femoral component within the limits studied did not influence tibiofemoral load transfer. CONCLUSIONS: Internal rotation of the femoral component will adversely influence medial compartment load transfer and could lead to premature polyethylene wear on the medial side.

Does Maximal External Tibial Component Rotation Influence Tibiofemoral Load Distribution in the Primary Knee Arthroplasty Setting: A Comparison of Neutral vs Maximal Anatomical External Rotatory States.

BACKGROUND: Tibial component rotation at time of knee arthroplasty can influence conformity, load transmission across the polyethylene surface, and perhaps ultimately determined survivorship. Optimal tibial component rotation on the cut surface is reliant on standard per operative manual stressing. This subjective assessment aims to balance constraint and stability of the articulation through a full arc of movement. METHODS: Using a cadaveric model, computer navigation and under defined, previously validated loaded conditions mimicking the in vivo setting, the influence of maximal tibial component external rotation compared with the neutral state was examined for changes in laxity and tibiofemoral continuous load using 3D displacement measurement and an orthosensor continuous load sensor implanted within the polyethylene spacer in a simulated single radius total knee arthroplasty. RESULTS: No significant difference was found throughout arc of motion (0-115 degrees of flexion) for maximal varus and/or valgus or rotatory laxity between the 2 states. The neutral state achieved equivalence for mediolateral load distribution at each point of flexion. We have found that external rotation of the tibial component increased medial compartment load in comparison with the neutral position. Compared with the neutral state, external rotation consistently effected a marginal, but not significant reduction in lateral load under similar loading conditions. The effects were most pronounced in midflexion. CONCLUSION: On the basis of these findings, we would advocate for the midtibial tubercle point to determine tibial component rotation and caution against component external rotation.

Patellar thickness and lateral retinacular release affects patellofemoral kinematics in total knee arthroplasty.

PURPOSE: To study the effect of increasing patellar thickness (overstuffing) on patellofemoral kinematics in total knee arthroplasty and whether subsequent lateral retinacular release would restore the change in kinematics. METHODS: The quadriceps of eight fresh-frozen knees were loaded on a custom-made jig. Kinematic data were recorded using an optical tracking device for the native knee, following total knee arthroplasty (TKA), then with patellar thicknesses from -2 to +4 mm, during knee extension motion. Staged lateral retinacular releases were performed to examine the restoration of normal patellar kinematics. RESULTS: Compared to the native knee, TKA led to significant changes in patellofemoral kinematics, with significant increases in lateral shift, tilt and rotation. When patellar composite thickness was increased, the patella tilted further laterally. Lateral release partly corrected this lateral tilt but caused abnormal tibial external rotation. With complete release of the lateral retinaculum and capsule, the patella with an increased thickness of 4 mm remained more laterally tilted compared to the TKA with normal patellar thickness between 45° and 55° knee flexion and from 75° onwards. This was on average by 2.4° ± 2.9° (p < 0.05) and 2.°9 ± 3.0° (p < 0.01), respectively. Before the release, for those flexion ranges, the patella was tilted laterally by 4.7° ± 3.2° and 5.4° ± 2.7° more than in the TKA with matched patellar thickness. CONCLUSION: Patellar thickness affects patellofemoral kinematics after TKA. Although lateral tilt was partly corrected by lateral retinacular release, this affected the tibiofemoral kinematics. LEVEL OF EVIDENCE: IV.

Lack of evidence to support present medial release methods in total knee arthroplasty.

PURPOSE: The aim of this review was to identify a reliable sequential medial release protocol for restoration of soft tissue balance in total knee arthroplasty of the varus osteoarthritic knee and to allow for improved intraoperative decision-making. METHOD: Current medial release sequences and applicability based upon pre-operative deformity have been reviewed. Furthermore, risks associated with over release, and the necessity of medial release, are discussed. RESULTS: The different medial release sequences are discussed in relation to pre-operative deformity, along with potential complications associated with medial release. It was found that release sequences may include the deep and superficial components of the medial collateral ligament, the posteromedial capsule, the posterior oblique ligament, the pes anserinus (pes A), and tendons of the semimembranosus and medial gastrocnemius muscle. The sequences described were found to vary substantially between studies, and very few studies had systematically quantified the effect of each release on balance. CONCLUSION: While medial release is the standard intraoperative mode of balancing, there is a lack of evidence to support current methods. The correct method for defining intraoperatively the sequence, extent and magnitude of releases required remains ill-defined. It could be argued that the classic extensive medial release may be unnecessary and may be associated with iatrogenic injury to the pes A and saphenous nerve, instability and abnormal knee kinematics. Minimal medial release may allow for improved soft tissue balancing leading ultimately to improved functional outcome. LEVEL OF EVIDENCE: V (expert opinion).

Intraoperative near-infrared fluorescence guided surgery using indocyanine green (ICG) may aid the surgical removal of benign bone and soft tissue tumours.

BACKGROUND: Benign bone and soft tissue tumours encompass a broad, heterogenous range of tumours with varying clinical characteristics. These are often managed surgically with either curettage or marginal excision, but unfortunately have high rates of local recurrence. Indocyanine green (ICG) is a fluorescent dye which can be used to identify solid malignancies intraoperatively but its use is not yet established in benign bone and soft tissue tumours. This study aims to assess whether these tumours fluoresce when administered with ICG pre-operatively and whether this helps surgeons to identify tumour intra-operatively. PATIENTS AND METHODS: Patients with locally aggressive benign bone and soft tissue tumours were administered with 25-75 mg of ICG preoperatively at the induction of anaesthesia. Fluorescence was imaged intraoperatively using the Stryker SPY-PHI camera. RESULTS: Of the 12 patients included, 11 tumours fluoresced. The surgeons felt the fluorescence guided the procedure in 7 out of the 11 cases which fluoresced. It was felt to be particularly useful in the curettage of bone tumours, in which curettage could be repeated until the absence of fluorescence on imaging. After 12 months, no patients had local recurrence of the tumour. There were no adverse events recorded in this study and surgeons found the technology acceptable. CONCLUSIONS: The use of ICG for fluorescence guided surgery is a promising technology to improve outcomes of surgery for benign bone and soft tissue tumours. Further, longer term, study with a control arm is needed to identify whether it results in a reduction in the local recurrence rate.

What Is the Significance of Indeterminate Pulmonary Nodules in High-Grade Soft Tissue Sarcomas? A Retrospective Cohort Study.

BACKGROUND: Sarcomas are rare, aggressive cancers which frequently metastasise to the lungs. Following diagnosis, patients typically undergo staging by means of a CT scan of their chest. This often identifies indeterminate pulmonary nodules (IPNs), but the significance of these in high-grade soft tissue sarcoma (STS) is unclear. Identifying whether these are benign or malignant is important for clinical decision making. This study analyses the clinical relevance of IPNs in high-grade STS. METHODS: All patients treated at our centre for high-grade soft tissue sarcoma between 2010 and 2020 were identified from a prospective database. CT scans and their reports were reviewed, and survival data were collected from patient records. RESULTS: 389 suitable patients were identified; 34.4% had IPNs on their CT staging scan and 20.1% progressed into lung metastases. Progression was more likely with IPNs ≥ 5 mm in diameter (p = 0.006), multiple IPNs (p = 0.013) or bilateral IPNs (p = 0.022), as well as in patients with primaries ≥ 5 cm (p = 0.014), grade 3 primaries (p = 0.009) or primaries arising deep to the fascia (p = 0.041). The median time to progression was 143 days. IPNs at diagnosis were associated with an increased risk of developing lung metastases and decreased OS in patients with grade 3 STS (p = 0.0019 and p = 0.0016, respectively); this was not observed in grade 2 patients. CONCLUSIONS: IPNs at diagnosis are associated with significantly worse OS in patients with grade 3 STS. It is crucial to consider the primary tumour as well as the IPNs when considering the risk of progression. Surveillance CT scans should be carried out within 6 months.

The importance of clear margins in myxofibrosarcoma: Improving local control by means of staged resection and reconstruction.

INTRODUCTION: Myxofibrosarcomas are associated with a locally infiltrative growth pattern, making a clear-margin resection margin challenging. This leads to high local recurrence rates. While immediate wound closure and adjuvant radiotherapy has been proposed to mitigate incomplete excisions, we present our experience treating myxofibrosarcomas with staged excisions until clear margins are obtained, prior to reconstruction. METHODS: All patients with myxofibrosarcomas treated with a curative intent at our centre between 2009 and 2019 were identified. Patient demographics, tumour characteristics, number of resections, method of reconstruction, adjuvant therapy, complications, local recurrence rates, length of hospital stay and overall survival were assessed. RESULTS: 97 consecutive eligible patients were identified. Forty-six (47%) had positive margins reported following a first resection. The median number of resections required to obtain clear margins was two and the median time from first excision to definitive wound closure was 15 days. Local recurrence rate for the whole cohort was 14%. Patients who had staged resection until clear margins were obtained had a significantly lower rate of local recurrence compared to those who had positive margins at time of reconstruction (p-value = 0.001). The estimated 5-year disease-specific survival for the whole cohort was 93%. DISCUSSION: Obtaining clear margins in myxofibrosarcoma via staged resections was associated with lower local recurrence rates for patients who had an initial resection with positive margins. The outcomes of performing staged resections are equivalent to patients for whom a clear margin were obtained in the first instance.

Surgical Advances in Osteosarcoma.

Osteosarcoma (OS) is the most common primary bone cancer in children and, unfortunately, is associated with poor survival rates. OS most commonly arises around the knee joint, and was traditionally treated with amputation until surgeons began to favour limb-preserving surgery in the 1990s. Whilst improving functional outcomes, this was not without problems, such as implant failure and limb length discrepancies. OS can also arise in areas such as the pelvis, spine, head, and neck, which creates additional technical difficulty given the anatomical complexity of the areas. We reviewed the literature and summarised the recent advances in OS surgery. Improvements have been made in many areas; developments in pre-operative imaging technology have allowed improved planning, whilst the ongoing development of intraoperative imaging techniques, such as fluorescent dyes, offer the possibility of improved surgical margins. Technological developments, such as computer navigation, patient specific instruments, and improved implant design similarly provide the opportunity to improve patient outcomes. Going forward, there are a number of promising avenues currently being pursued, such as targeted fluorescent dyes, robotics, and augmented reality, which bring the prospect of improving these outcomes further.

Intraoperative Near-Infrared Fluorescence Guided Surgery Using Indocyanine Green (ICG) for the Resection of Sarcomas May Reduce the Positive Margin Rate: An Extended Case Series.

BACKGROUND: Sarcomas are rare, aggressive cancers which can occur in any region of the body. Surgery is usually the cornerstone of curative treatment, with negative surgical margins associated with decreased local recurrence and improved overall survival. Indocyanine green (ICG) is a fluorescent dye which accumulates in sarcoma tissue and can be imaged intraoperatively using handheld near-infrared (NIR) cameras, theoretically helping guide the surgeon's resection margins. METHODS: Patients operated on between 20 February 2019 and 20 October 2021 for intermediate to high grade sarcomas at our centres received either conventional surgery, or were administered ICG pre-operatively followed by intra-operative NIR fluorescence guidance during the procedure. Differences between the unexpected positive margin rates were compared. RESULTS: 115 suitable patients were identified, of which 39 received ICG + NIR fluorescence guided surgery, and 76 received conventional surgery. Of the patients given ICG, 37/39 tumours fluoresced, and surgeons felt the procedure was guided by the intra-operative images in 11 cases. Patients receiving ICG had a lower unexpected positive margin rate (5.1% vs. 25.0%, p = 0.01). CONCLUSIONS: The use of NIR fluorescence cameras in combination with ICG may reduce the unexpected positive margin rate for high grade sarcomas. A prospective, multi-centre randomised control trial is now needed to validate these results.

What is a balanced knee replacement?

For multifactorial reasons an estimated 20% of patients remain unsatisfied after total knee arthroplasty (TKA).Appropriate tension of the soft tissue envelope encompassing the knee is important in total knee arthroplasty and soft tissue imbalance contributes to several of the foremost reasons for revision TKA, including instability, stiffness and aseptic loosening.There is debate in the literature surrounding the optimum way to achieve balancing of a total knee arthroplasty and there is also a lack of an accepted definition of what a balanced knee replacement is.It may be intuitive to use the native knee as a model for balancing; however, there are many difficulties with translating this into a successful prosthesis.One of the foundations of TKA, as described by Insall, was that although the native knee has more weight transmitted through the medial compartment this was to be avoided in a TKA as it would lead to uneven wear and early failure. There is a focus on achieving symmetrical tension and pressure and subsequent 'balance' in TKA, but the evidence from cadaveric studies is that the native knee is not symmetrically balanced.As we are currently trying to design an implant that is not based on its anatomical counterpart, is it possible to create a truly balanced prosthesis or to even to define what that balance is? The authors have reviewed the current evidence surrounding TKA balancing and its relationship with the native knee. Cite this article: EFORT Open Rev 2018;3:614-619. DOI: 10.1302/2058-5241.3.180008.

Influence of increasing construct constraint in the presence of posterolateral deficiency at knee replacement: A biomechanical study.

When faced with posterolateral corner (PLC) deficiency, surgeons must choose a total knee replacement (TKR) construct that provides the appropriate level of constraint. This should match the internal constraint of the device to the soft tissue host laxity pattern. Little guidance is available peroperatively, with factors influencing final component choice remaining ill defined. This study aimed to quantify the effect of PLC insufficiency on the "envelope of laxity" (EoL) after TKR and the effect of increasingly component constraint upon knee behavior through a functional arc of flexion. Using computer navigation, mixed effect modeling and loaded cadaveric legs--laxity was quantified under separate states: the native knee, after implantation of a posterior stabilized (PS)-TKR, after sectioning the lateral (fibular) collateral ligament and popliteus tendon (PS-TKR-PLC), and after re-implantation with a semi-constrained "total stabilized" knee replacement (TS-TKR). Laxity was quantified from 0 to 110° of flexion for anterior draw, varus-valgus, and internal-external rotation. Implantation of the PS-TKR was consistently associated with increased constraint when compared to the native knee. PLC sectioning led to significantly increased laxity during varus stress from mid to deep flexion. Revision to a TS-TKR construct restored constraint mimicking that of the primary state but only for the arc of motion 0-90°. In a posterolateral deficient state, a fixed bearing semi-constrained TS-TKR restored the knee to near normal kinematics but this was only achieved from an arc of motion 0-90° of flexion. At higher flexion angles, there remained an unfavorable laxity pattern with varus stress opening.

How does laxity after single radius total knee arthroplasty compare with the native knee?

Patients with total knee arthroplasties (TKAs) continue to report dissatisfaction in functional outcome. Stability is a major factor contributing to functionality of TKAs. Implants with single-radius (SR) femoral components are proposed to increase stability throughout the arc of flexion. Using computer navigation and loaded cadaveric legs, we characterized the "envelope of laxity" (EoL) offered by a SR cruciate retaining (CR)-TKA compared with that of the native knee through the arc of flexion in terms of anterior drawer, varus/valgus stress, and internal/external rotation. In both the native knee and the TKA laxity increased with increasing knee flexion. Laxities measured in the three planes of motion were generally comparable between the native knee and TKA from 0° to 110° of flexion. Our results indicate that the SR CR-TKA offers appropriate stability in the absence of soft tissue deficiency.

The effect of femoral component rotation on the extensor retinaculum of the knee.

Malrotation of the femoral component may cause patellofemoral complications after total knee replacement (TKR). We hypothesized that femoral component malrotation would cause excessive lengthening of the retinacula. Retinacular length changes were measured by threading fine sutures along them and attaching these to the patella and to displacement transducers. The knee post-TKR was flexed-extended while the quadriceps were tensed, then the measurements repeated after rotating the femoral component 5 degrees internally and then 5 degrees externally. Internal rotation shortened the medial patellofemoral ligament (MPFL) significantly from 100 degrees to 0 degrees extension. External rotation lengthened the MPFL significantly from 90 degrees to 0 degrees extension. The transverse fibers of the lateral retinaculum showed no significant differences. The MPFL attaches directly from bone to bone, so it was lengthened directly by movement of the trochlea and patella, whereas the deep transverse fibers of the lateral retinaculum attach to the mobile iliotibial tract, so they were not lengthened directly.

The transpatellar approach for the knee in the laboratory.

This paper describes a longitudinal patellar-splitting approach to the knee that includes provision for accurate reconstruction. Our in vitro experiments showed that patellofemoral kinematics and length-change patterns of specific bands of the peripatellar retinacula were not changed significantly by opening and closing the knee via the transpatellar approach. This surgical approach will be useful for in vitro experiments on the knee, when effects due to alterations of internal structures such as cruciate ligament reconstructions or joint replacement are to be studied, avoiding confounding effects caused by changes to the retinacula.

Length change patterns of the extensor retinaculum and the effect of total knee replacement.

Patellofemoral dysfunction following total knee replacement (TKR) is a significant clinical problem, but little information exists on the mechanics of the patellofemoral retinacula or the effects of TKR on these structures. We hypothesized that TKR would cause significant elongation of the retinacula. Retinacular length changes were measured by threading sutures along the retinacula, fixing the sutures to the patella and the iliotibial band (ITB), and attaching the femoral ends to displacement transducers. The intact knee was flexed-extended while the quadriceps and ITB were tensed and the retinacular length change patterns were recorded. The measurements were repeated post-TKR. The medial patellofemoral ligament (MPFL) was close to isometric, stretching 2 mm in terminal knee extension, whereas the lateral retinaculum slackened 8 mm from 110 degrees to 0 degrees flexion. TKR did not cause significant elongation of either of the retinacula, the largest change being 3 mm elongation of the MPFL around 40 degrees , which stretched the MPFL by 1.4 mm above its maximum natural length. Thus, this work did not support the hypothesis that TKR causes significant elongation of the retinacula sufficient to affect knee function.