Aims

The diagnosis of joint infections is an inexact science using combinations of blood inflammatory markers and microscopy, culture, and sensitivity of synovial fluid (SF). There is potential for small molecule metabolites in infected SF to act as infection markers that could improve accuracy and speed of detection. The objective of this study was to use nuclear magnetic resonance (NMR) spectroscopy to identify small molecule differences between infected and noninfected human SF.

Aims

Metabolic profiling is a top-down method of analysis looking at metabolites, which are the intermediate or end products of various cellular pathways. Our primary objective was to perform a systematic review of the published literature to identify metabolites in human synovial fluid (HSF), which have been categorized by metabolic profiling techniques. A secondary objective was to identify any metabolites that may represent potential biomarkers of orthopaedic disease processes.

Objectives

The objective of this study was to perform a meta-analysis of all randomised controlled trials (RCTs) comparing surgical and non-surgical management of fractures of the proximal humerus, and to determine whether further analyses based on complexity of fracture, or the type of surgical intervention, produced disparate findings on patient outcomes.

Aim: To accurately assess cross-sectional areas of the MFLs and distinguish between the mechanical properties of the anterior and posterior meniscofemoral ligaments.

Methods: Twenty-eight fresh frozen cadaveric knees were dissected to isolate the lateral meniscus and MFLs, which remained attached to the femur. The cross-sectional areas of MFLs were determined using the Race-Amis¹ casting method for measurement. The ligaments were then tensile tested in an Instron materials testing machine. The stress and strain in each sample was calculated from measurements of cross sectional area, load applied, and increase in length,.

Results: The mean cross sectional area for the anterior MFL (aMFL) was 14.7 mm² (±14.8mm²) whilst that of the posterior MFL (pMFL) was 20.9mm² (±11.6mm²). The mean loads to failure were 300.5N (±155.0N) for the aMFL and 302.5N (±157.9N) for the pMFL, with elastic moduli of 281MPa (±239MPa) and 227MPa (±128MPa) respectively. There were no significant differences in structural or material properties between the two MFLs. When compared with the posterior cruciate ligament (PCL), the mean ultimate loads of the MFLs were similar to those of the posterior bundle of the PCL (pPC), and their elastic moduli were analogous to the anterior bundle (aPC).

Discussion: This is the first study to distinguish between the properties of the aMFL and pMFL, and indicates that both ligaments must be given equal consideration when formulating hypotheses on function. The aMFL and pMFL may also serve mutually distinct functions in the human knee. Previous authors² have commented that the reciprocal tightening and slackening of the aPC (taut in flexion) and pPC (taut in extension) indicates a difference in function of these two components of the PCL. Others³ have similarly commented on the reciprocal tightening and slackening of the two MFLs. This may also indicate differing functions for these ligaments. It is proposed that the aMFL supplements the function of the aPC, whilst the pMFL supplements the function of the pPC. This hypothesis stimulates debate on preservation of these structures during PCL reconstruction.

Race A., Amis A.A., 1996. Cross-sectional area measurement of soft tissue. A new casting method. Journal of Biomechanics 29(9), 1207–1212.

Aim: To accurately identify the meniscofemoral ligaments in cadaveric human specimens, and to determine anatomical variations in the posterior cruciate ligament that may lead to mis-identification of these structures.

Methods: A total of 79 fresh frozen knees were examined from 45 cadavers Combined anterior and posterior approaches were used to inspect the vicinity of the posterior cruciate ligament (PCL) for the presence of the anterior and posterior meniscofemoral ligaments. The anterior approach utilised a medial parapatellar incision followed by division of the anterior cruciate ligament, whilst a midline posterior arthrotomy was used for the posterior approach. Further dissection facilitated inspection of the meniscal and femoral attachments of the MFLs, and measurement of their lengths. Videos of MFL and PCL motion during passive flexion of the cadaveric were also performed.

Results: In total, 74 (94%) of the 79 specimens contained at least one meniscofemoral ligament. The posterior meniscofemoral ligament (pMFL) was present in 56 (71%) specimens, whilst the anterior meniscofemoral ligament (aMFL) was present in 58 specimens (73%). Both ligaments coexisted in 40 (51%) of knees. In 15 specimens the PCL was seen to have oblique fibres, which attached proximal to the tibial attachment of the main part of the PCL. We termed this “the false pMFL”, as it could be easily mis-identified as the posterior meniscofemoral ligament. Several other anatomical variations were also identified. The mean length of the aMFL was 20.7±3.9mm, whilst that of the pMFL was 23±4.2mm. Although the lengths of the MFLs were relatively constant, there was a wide variation in thickness.

Discussion: This study confirms the high incidence of at least one MFL in humans, which suggests a functional role for these structures. The oblique fibres of the PCL can be readily mis-identfied as the pMFL. These caveats should be borne in mind, during both arthroscopic examination and in the interpretation of magnetic resonance imaging (MRI) scans of the knee. Although some variations of the MFLs have been reported on MRI imaging2, there has been no note of the oblique fibres of the PCL reported in the present study. As this variation was present in almost one in five of our specimens, its appearance on MRI scanning requires investigation.

The function of the meniscofemoral ligaments is undetermined, although many hypotheses comment on a role in guiding the motion of the lateral meniscus during knee flexion. Other possibilities include a function as a secondary restraint supplementing the posterior cruciate ligament.