Imaging the implant-soft tissue interactions in total knee arthroplasty

Popliteal tendon impingement as a cause of pain following total knee arthroplasty: a systematic review

INTRODUCTION

Popliteal tendon impingement (PTI) is an under-recognized cause of persistent pain following total knee arthroplasty (TKA). The purpose of the systematic review was to summarize and outline successful strategies in the diagnosis and management of PTI.

METHODS

A systematic review following the PRISMA guidelines was performed for four databases: MEDLINE (Pubmed), Ovid EMBASE, Web of Science, and Cochrane Database. It was registered in the International Prospective Register for Systematic Reviews and Meta-analysis (PROSPERO) under the registration number: CRD42023398723. The risk of bias assessment was performed using the criteria of the methodological index for non-randomized studies (MINORS).

RESULTS

A total of 8 studies were included. There were 2 retrospective case series and 6 case reports. The follow-up ranged from 6 to 30 months. Two studies described PTI as an intraoperative phenomenon during TKA with "snapping"; whilst 6 studies described indications and outcomes for arthroscopic tenotomy for PTI following TKA. In making the diagnosis, there was concurrence that the posterolateral pain should be focal and that dynamic ultrasonography and diagnostic injection play an important role. Two specific clinical tests have been described. There was no consistency regarding the need for imaging. There were no reports of instability following popliteal tendon tenotomy or other complications.

CONCLUSION

PTI should be suspected as a cause for persistent focal pain at the posterolateral knee following TKA. The diagnosis can be suspected on imaging and should be confirmed with dynamic ultrasonography and an ultrasound-guided diagnostic injection. An arthroscopic complete tenotomy of the tendon can reliably alleviate pain and relies on correct diagnosis. There is no evidence for clinically relevant negative biomechanical consequences following tenotomy.

LEVEL OF EVIDENCE

Systematic Review of Level IV and V studies.

Fourier-transform infrared spectroscopy: a universal optical sensing technique with auspicious application prospects in the diagnosis and management of autoimmune diseases

Autoimmune diseases (AIDs) are poorly understood clinical syndromes due to breakdown of immune tolerance towards specific types of self-antigens. They are generally associated with an inflammatory response mediated by lymphocytes T, autoantibodies or both. Ultimately, chronic inflammation culminates in tissue damages and clinical manifestations. AIDs affect 5% of the world population, and they represent the main cause of fatality in young to middle-aged females. In addition, the chronic nature of AIDs has a devastating impact on the patient's quality of life. It also places a heavy burden on the health care system. Establishing a rapid and accurate diagnosis is considered vital for an ideal medical management of these autoimmune disorders. However, for some AIDs, this task might be challenging. Vibrational spectroscopies, and more particularly Fourier-transform infrared (FTIR) spectroscopy, have emerged as universal analytical techniques with promising applications in the diagnosis of various types of malignancies and metabolic and infectious diseases. The high sensitivity of these optical sensing techniques and their minimal requirements for test reagents qualify them to be ideal analytical techniques. The aim of the current review is to explore the potential applications of FTIR spectroscopy in the diagnosis and management of most common AIDs. It also aims to demonstrate how this technique has contributed to deciphering the biochemical and physiopathological aspects of these chronic inflammatory diseases. The advantages that can be offered by this optical sensing technique over the traditional and gold standard methods used in the diagnosis of these autoimmune disorders have also been extensively discussed.

Arthroscopic popliteal tenotomy grants satisfactory outcomes in total knee arthroplasty with persistent localised posterolateral pain and popliteus tendon impingement

PURPOSE

The purpose was to estimate the prevalence of popliteus tendon impingement following TKA, and to describe the characteristics and the differential diagnosis protocol for this rare condition. The hypothesis was that arthroscopic popliteal tenotomy in TKA patients with suspected popliteus tendon impingement would relieve pain and improve satisfaction.

METHODS

Of 741 TKAs performed over three years, eight (1.1%, all women) had suspected popliteus tendon impingement, of which seven had severe localised posterolateral knee pain and one global knee pain. Upon confirmation of popliteus tendon impingement, arthroscopic popliteal tenotomy was performed, and outcomes (Pain on visual analogue scale (pVAS; best, 0; worst, 10), Oxford Knee Score (OKS; best, 48; worst, 0) and satisfaction (best, 100%; worst, 0%) assessed at mean 18-month follow-up.

RESULTS

At four to 30 months after TKA, arthroscopic exploration revealed popliteus tendon impingement in all eight knees. Six reported complete pain relief (pVAS, 0) the day following arthroscopic popliteal tenotomy, whilst one reported some residual pain (pVAS, 2). The remaining patient with global pain reported no pain relief, and required revision TKA at 12 months. Excluding the revised TKA, OKS was between 19 and 43, and satisfaction was rated ≥ 80% in five of the remaining seven patients.

CONCLUSIONS

Arthroscopic popliteal tenotomy relieved symptoms in TKA patients with persistent localised posterolateral pain and a positive popliteus test. These findings suggest that the popliteus test is reliable to diagnose popliteus tendon impingement following TKA, which could be treated by arthroscopic popliteal tenotomy.

LEVEL OF EVIDENCE

Level IV, Small case series.

Benefits of CT Scanning for the Management of Knee Arthritis and Arthroplasty

This review investigated the potential value of computed tomography (CT) scans for the evaluation and management of knee arthritis and arthroplasty. Specifically, we evaluated the following: (1) assessment of arthritis within knee compartments, (2) patellofemoral joint assessment, (3) implant sizing prediction, (4) component alignment, (5) soft-tissue protection, and (6) potential concerns with radiation exposure. To compare if CT or X-ray imaging is more accurate and clinically relevant, a search was performed using Boolean search operators and terms: "CT," "radiograph," "joint alignment," "knee," and "arthroplasty," which yielded 661 results. Studies were evaluated based on (1) assessment of arthritis within knee compartments, (2) patellofemoral joint assessment, (3) implant sizing prediction, (4) component alignment, (5) soft-tissue protection, and (6) potential concerns with radiation exposure. Correlative and comparative analyses of imaging modalities to pre-, intra-, and postoperative clinical and patient-related factors were performed for the 63 included studies. CT scans were found to better detect medial and lateral arthritic changes, bony deformities, subchondral cysts, and cartilage losses. CT scans were shown to 99% accurately predict prosthetic sizes preoperatively. CT scans can also help better visualize surrounding anatomy, such as the posterior cruciate ligament, and have therefore been linked to better soft tissue protection during total knee arthroplasty. Although radiation is a potential concern, newer imaging protocols have comparable exposure to plain radiographs. Compared with plain radiographs, CT scans were found to be more accurate and provide more clinically relevant data. Therefore, the authors recommend the use of CT for the evaluation of certain patients with arthritis and for preoperative planning for knee arthroplasty.

Development of a total hip replacement phantom for the assessment of CT-image quality

BACKGROUND

The quality of computed tomography (CT) imaging is important when used to judge the success of joint replacement surgery. Metal artefacts are a known source of error, typically compensated by noise reduction software.

PURPOSE

To develop a transportable and stable system for the assessment of image quality of bone lesions around orthopedic implants.

MATERIAL AND METHODS

The design and manufacture of a bone-implant-phantom is described, which is based on a calf acetabulum with surrounding pelvic bone structures. Bone lesions of several sizes were created in the acetabulum before implanting the cup of an uncemented hip prosthesis, which was fixed with a stainless-steel bone screw. Plastic strips were placed on a cobalt-chromium stemmed femoral component, simulating typical bone lesions around loosening or infected prostheses, before embedding the stem in material similar to bone and shaped like a femur. The head of the femoral component was then placed in the acetabular cup and CT scans were produced.

RESULTS

It was possible to construct a durable CT hip phantom for quality assurance work. The usability of different materials and the choices made for the phantom are discussed.

CONCLUSION

It is possible to construct a durable joint implant phantom for quality assurance and scanner hardware and software assessment with limited resources. The phantom was successfully used in the assessment of the hardware and software performance of different CT scanners.

Being Underweight Is Associated with Worse Surgical Outcomes of Total Knee Arthroplasty Compared to Normal Body Mass Index in Elderly Patients

Purpose

Being underweight has never been studied in relation to the radiologic and clinical outcomes of total knee arthroplasty (TKA) in elderly patients. The aim of this study was to determine the effect of being underweight on TKA radiological and clinical outcomes and to investigate whether being underweight influences postoperative complications compared to normal body mass index (BMI) in elderly patients.

Patients and Methods

A total of 118 female patients aged 65 years or older with BMI < 25 kg/m² who underwent primary TKA were divided into two groups based on BMI: group A: 18.5 kg/m² < BMI < 25 kg/m²; group B: BMI < 18.5 kg/m². The radiologic and clinical outcomes were evaluated at follow-up of 6, 12, and 24 months after surgery such as the hip-knee-ankle angle, the American Knee Society (AKS) score, Western Ontario and McMaster University score (WOMAC), and patellofemoral (PF) scale. Moreover, postoperative complications during follow-up were investigated.

Results

Preoperative clinical scores did not differ significantly between the two groups. Postoperative WOMAC pain (1.8 ± 1.9 versus 3.4 ± 2.6, p = 0.02), WOMAC function (12.4 ± 8.1 versus 16.5 ± 8.5, p = 0.012) and PF scales (26.1 ± 3.6 versus 23.7 ± 4.1, p = 0.002) were worse in the underweight group at 12 and 24 months after surgery. The frequency of postoperative complications did not differ significantly between groups. In multivariate linear regression analysis, underweight patient group was significantly associated with worse postoperative WOMAC and PF scores (p = 0.002, 0.005).

Conclusion

Although postoperative complications of TKA did not differ between groups, underweight patients had worse clinical outcomes of TKA compared to patients with normal BMI in elderly patients. Therefore, care should be taken when performing TKA in elderly underweight patients.

Biomechanical comparison of Thiel embalmed and fresh frozen nerve tissue

The aim of this study was to determine the effect of Thiel embalming on the biomechanical properties of nerve tissue, to validate the use of Thiel embalmed bodies as a reliable model system for obtaining biomechanical data to supplement neurodynamic models, for anesthesiological and neurosurgical training and for future preclinical test set-ups involving nerve tissue. Upon the arrival of a body at the anatomy department, a fresh median nerve was harvested, the harvest site was sutured and following the Thiel embalming procedure the Thiel embalmed median nerve of the opposing wrist was harvested. Micro CT was performed to establish the cross-sectional area and biomechanical tensile testing was performed to compare the Young's modulus/elasticity of fresh frozen and Thiel embalmed nerves. Thiel embalming did not cause a significant difference in elasticity when comparing Thiel embalmed and fresh frozen specimens. A correlation was found between the cross-sectional area of Thiel embalmed nerve specimens and their Young's modulus. Thiel embalming does not significantly alter the elasticity of nerve tissue compared to fresh frozen nerve tissue. Similar shapes were observed when comparing the stress/strain curves of both specimen types. This indicates that Thiel embalmed nerve tissue is a viable alternative for using fresh frozen specimens when investigating biomechanical principles/mechanisms. Some specimens showed a reversed trend in Young's modulus that could be related to slight differences in embalming outcome, so caution is advised when Thiel embalmed specimens are used to obtain raw numerical data for direct application in the clinic.

Optimising position and stability in total knee arthroplasty

Alignment and stability are two key factors for success in total knee arthroplasty (TKA). Several techniques have been advocated, the two best known being measured resection and tensioned gaps.Dogma and fuzzy wording have cast an obscure shadow on the dualistic discussion between proponents of both techniques.This review is an attempt to clarify definitions, analyse the flaws and pitfalls in the different techniques and make some suggestions for improvement. Cite this article: EFORT Open Rev 2017;2. DOI: 10.1302/2058-5241.2.170001. Originally published online at www.efortopenreviews.org.