Aims

Although knee osteoarthritis (OA) is diagnosed and monitored radiologically, actual full-thickness cartilage loss (FTCL) has rarely been correlated with radiological classification. This study aims to analyze which classification system correlates best with FTCL and to assess their reliability.

The radiological and MRI appearances of 24 knees with patellar tendonitis resistant to conservative therapy were analysed to identify the characteristic MRI appearance and to determine if the patellar morphology was abnormal. A significant thickening of the tendon was found in all cases; this was a more reliable diagnostic feature than a high signal within the superior posterior and central aspect of the tendon at its proximal attachment

The site of the lesion shown by MRI is more compatible with impingement of the inferior pole of the patella against the patellar tendon than a stress overload of the tendon. There were no significant differences in the length of the patella, inferior pole or length of the articular surface when the patellar morphology was compared with that of a matched control group.

The aim of this study was to review the early outcome of the Femoro-Patella Vialla (FPV) joint replacement. A total of 48 consecutive FPVs were implanted between December 2007 and June 2011. Case-note analysis was performed to evaluate the indications, operative histology, operative findings, post-operative complications and reasons for revision. The mean age of the patients was 63.3 years (48.2 to 81.0) and the mean follow-up was 25.0 months (6.1 to 48.9). Revision was performed in seven (14.6%) at a mean of 21.7 months, and there was one re-revision. Persistent pain was observed in three further patients who remain unrevised. The reasons for revision were pain due to progressive tibiofemoral disease in five, inflammatory arthritis in one, and patellar fracture following trauma in one. No failures were related to the implant or the technique. Trochlear dysplasia was associated with a significantly lower rate of revision (5.9% vs 35.7%, p = 0.017) and a lower incidence of revision or persistent pain (11.8% vs 42.9%, p = 0.045).

Focal patellofemoral osteoarthritis secondary to trochlear dysplasia should be considered the best indication for patellofemoral replacement. Standardised radiological imaging, with MRI to exclude overt tibiofemoral disease should be part of the pre-operative assessment, especially for the non-dysplastic knee.

Cite this article: Bone Joint J 2013;95-B:793–7.

Aims

Unicompartmental knee arthroplasty (UKA) is the preferred treatment for anterior medial knee osteoarthritis (OA) owing to the rapid postoperative recovery. However, the risk factors for UKA failure remain controversial.

Aims

Patient dissatisfaction is not uncommon following primary total knee arthroplasty. One proposed method to alleviate this is by improving knee kinematics. Therefore, we aimed to answer the following research question: are there significant differences in knee kinematics based on the design of the tibial insert (cruciate-retaining (CR), ultra-congruent (UC), or medial congruent (MC))?

Aims

Total knee arthroplasty (TKA) is a common and safe orthopaedic procedure. Zimmer Biomet's NexGen is the second most popular brand of implant used in the UK. The primary cause of revision after the first year is aseptic loosening. We present our experience of using this implant, with significant concerns around its performance with regards early aseptic loosening of the tibial component.

Patient specific cutting guides generated by preoperative Magnetic Resonance Imaging (MRI) of the patient’s extremity have been proposed as a method of improving the consistency of Total Knee Arthroplasty (TKA) alignment and adding efficiency to the operative procedure. The cost of this option was evaluated by quantifying the savings from decreased operative time and instrument processing costs compared to the additional cost of the MRI and the guide. Coronal plane alignment was measured in an unselected consecutive series of 200 TKAs, 100 with standard instrumentation and 100 with custom cutting guides. While the cutting guides had significantly lower total operative time and instrument processing time, the estimated $322 savings was overwhelmed by the $1,500 additional cost of the MRI and the cutting guide. All measures of coronal plane alignment were equivalent between the two groups. The data does not currently support the proposition that patient specific guides add value to TKA

Aims

MRI has been suggested as an objective method of assessing anterior crucate ligament (ACL) graft “ligamentization” after reconstruction. It has been proposed that the MRI appearances could be used as an indicator of graft maturity and used as part of a return-to-sport assessment. The aim of this study was to evaluate the correlation between MRI graft signal and postoperative functional scores, anterior knee laxity, and patient age at operation.

Aims

The objective of this study is to assess the use of ultrasound (US) as a radiation-free imaging modality to reconstruct 3D anatomy of the knee for use in preoperative templating in knee arthroplasty.

Aims

In the last decade, interest in partial knee arthroplasties and bicruciate retaining total knee arthroplasties has increased. In addition, patient-related outcomes and functional results such as range of movement and ambulation may be more promising with less invasive procedures such as bicompartmental arthroplasty (BCA). The purpose of this study is to evaluate clinical and radiological outcomes after a third-generation patellofemoral arthroplasty (PFA) combined with a medial or lateral unicompartmental knee arthroplasty (UKA) at mid- to long-term follow-up.

Aims

Stiffness is a common complication after total knee arthroplasty (TKA). Pathogenesis is not understood, treatment options are limited, and diagnosis is challenging. The aim of this study was to investigate if MRI can be used to visualize intra-articular scarring in patients with stiff, painful knee arthroplasties.

Aims

The aim of this study was to compare robotic arm-assisted bi-unicompartmental knee arthroplasty (bi-UKA) with conventional mechanically aligned total knee arthroplasty (TKA) in order to determine the changes in the anatomy of the knee and alignment of the lower limb following surgery.

Aims

The Oswestry-Bristol Classification (OBC) was recently described as an MRI-based classification tool for the femoral trochlear. The authors demonstrated better inter- and intraobserver agreement compared to the Dejour classification. As the OBC could potentially provide a very useful MRI-based grading system for trochlear dysplasia, it was the aim to determine the inter- and intraobserver reliability of the classification system from the perspective of the non-founder.

Aims

The aim of this study was to determine and compare the congruency of the articular surface contact area of the patellofemoral joint (PFJ) during both active and passive movement of the knee with the use of an MRI mapping technique in both the stable and unstable PFJ.

Aims

In Asia and the Middle-East, people often flex their knees deeply in order to perform activities of daily living. The purpose of this study was to investigate the 3D kinematics of normal knees during high-flexion activities. Our hypothesis was that the femorotibial rotation, varus-valgus angle, translations, and kinematic pathway of normal knees during high-flexion activities, varied according to activity.

Objectives

The purpose of this study was to clarify the appearance of the reparative tissue on the articular surface and to analyse the properties of the reparative tissue after hemicallotasis osteotomy (HCO) using MRI T1ρ and T2 mapping.

Aims

The morphometry of the distal femur was largely studied to improve bone-implant fit in total knee arthroplasty (TKA), but little is known about the asymmetry of the posterior condyles. This study aimed to investigate the dimensions of the posterior condyles and the influence of externally rotating the femoral component on potential prosthetic overhang or under-coverage.

Patellar instability most frequently presents during adolescence. Congenital and infantile dislocation of the patella is a distinct entity from adolescent instability and measurable abnormalities may be present at birth. In the normal patellofemoral joint an increase in quadriceps angle and patellar height are matched by an increase in trochlear depth as the joint matures. Adolescent instability may herald a lifelong condition leading to chronic disability and arthritis.

Restoring normal anatomy by trochleoplasty, tibial tubercle transfer or medial patellofemoral ligament (MPFL) reconstruction in the young adult prevents further instability. Although these techniques are proven in the young adult, they may cause growth arrest and deformity where the physis is open. A vigorous non-operative strategy may permit delay of surgery until growth is complete. Where non-operative treatment has failed a modified MPFL reconstruction may be performed to maintain stability until physeal closure permits anatomical reconstruction. If significant growth remains an extraosseous reconstruction of the MPFL may impart the lowest risk to the physis. If minor growth remains image intensifier guided placement of femoral intraosseous fixation may impart a small, but acceptable, risk to the physis.

This paper presents and discusses the literature relating to adolescent instability and provides a framework for management of these patients.

Cite this article: Bone Joint J 2017;99-B:159–70.

Patellofemoral complications are common after total knee replacement (TKR). Leaving the patellar unsurfaced after TKR may lead to complications such as anterior knee pain, and re-operation to surface it. Complications after patellar resurfacing include patellar fracture, aseptic loosening, patellar instability, polyethylene wear, patellar clunk and osteonecrosis. Historically, patellar complications account for one of the larger proportions of causes of failure in TKR, however, with contemporary implant designs, complication rates have decreased. Most remaining failures relate to patellofemoral tracking. Understanding the causes of patellofemoral maltracking is essential to prevent these complications as well as manage them when they occur.

Cite this article: Bone Joint J 2014;96-B(11 Suppl A):84–6.

Improvements in the surgical technique of total knee replacement (TKR) are continually being sought. There has recently been interest in three-dimensional (3D) pre-operative planning using magnetic resonance imaging (MRI) and CT. The 3D images are increasingly used for the production of patient-specific models, surgical guides and custom-made implants for TKR.

The users of patient-specific instrumentation (PSI) claim that they allow the optimum balance of technology and conventional surgery by reducing the complexity of conventional alignment and sizing tools. In this way the advantages of accuracy and precision claimed by computer navigation techniques are achieved without the disadvantages of additional intra-operative inventory, new skills or surgical time.

This review describes the terminology used in this area and debates the advantages and disadvantages of PSI.

Objectives

Lower limb muscle power is thought to influence outcome following total knee replacement (TKR). Post-operative deficits in muscle strength are commonly reported, although not explained. We hypothesised that post-operative recovery of lower limb muscle power would be influenced by the number of satellite cells in the quadriceps muscle at time of surgery.

Objectives

This study aimed to investigate time-dependent gene expression of injured human anterior cruciate ligament (ACL), and to evaluate the histological changes of the ACL remnant in terms of cellular characterisation.

Component malalignment can be associated with pain following total knee replacement (TKR). Using MRI, we reviewed 50 patients with painful TKRs and compared them with a group of 16 asymptomatic controls to determine the feasibility of using MRI in evaluating the rotational alignment of the components. Using the additional soft-tissue detail provided by this modality, we also evaluated the extent of synovitis within these two groups. Angular measurements were based on the femoral transepicondylar axis and tibial tubercle. Between two observers, there was very high interobserver agreement in the measurements of all values. Patients with painful TKRs demonstrated statistically significant relative internal rotation of the femoral component (p = 0.030). There was relative internal rotation of the tibial to femoral component and combined excessive internal rotation of the components in symptomatic knees, although these results were significant only with one of the observers (p = 0.031). There was a statistically significant association between the presence and severity of synovitis and painful TKR (p < 0.001).

MRI is an effective modality in evaluating component rotational alignment.

Objectives

Numerous complications following total knee replacement (TKR) relate to the patellofemoral (PF) joint, including pain and patellar maltracking, yet the options for in vivo imaging of the PF joint are limited, especially after TKR. We propose a novel sequential biplane radiological method that permits accurate tracking of the PF and tibiofemoral (TF) joints throughout the range of movement under weightbearing, and test it in knees pre- and post-arthroplasty.

Objectives

There remains a lack of data on the reliability of methods to estimate tibial coverage achieved during total knee replacement. In order to address this gap, the intra- and interobserver reliability of a three-dimensional (3D) digital templating method was assessed with one symmetric and one asymmetric prosthesis design.

Valgus high tibial osteotomy for osteoarthritis of the medial compartment of the knee can be performed using medial opening- and lateral closing-wedge techniques. The latter have been thought to offer greater initial stability.

We measured and compared the stability of opening- and closing-wedge osteotomies fixed by TomoFix plates using radiostereometry in a series of 42 patients in a prospective, randomised clinical trial.

There were no differences between the opening- and closing-wedge groups in the time to regain knee function and full weight-bearing. Pain and knee function were significantly improved in both groups without any differences between them. All the osteotomies united within one year. Radiostereometry showed no clinically relevant movement of bone or differences between either group.

Medial opening-wedge high tibial osteotomy secured by a TomoFix plate offers equal stability to a lateral closing-wedge technique. Both give excellent initial stability and provide significantly improved knee function and reduction in pain, although the opening-wedge technique was more likely to produce the intended correction.

Our aims were to map the tibial footprint of the posterior cruciate ligament (PCL) using MRI in patients undergoing PCL-preserving total knee replacement, and to document the disruption of this footprint as a result of the tibial cut. In 26 consecutive patients plain radiography and MRI of the knee were performed pre-operatively, and plain radiography post-operatively.

The lower margin of the PCL footprint was located a mean of 1 mm (−10 to 8) above the upper aspect of the fibular head. The mean surface area was 83 mm² (49 to 142). One-third of patients (8 of 22) had tibial cuts made below the lowest aspect of the PCL footprint (complete removal) and one-third (9 of 22) had cuts extending into the footprint (partial removal). The remaining patients (5 of 22) had footprints unaffected by the cuts, keeping them intact.

Our study highlights the wide variation in the location of the tibial PCL footprint when referenced against the fibula. Proximal tibial cuts using conventional jigs resulted in the removal of a significant portion, if not all of the PCL footprint in most of the patients in our study. Our findings suggest that when performing PCL-retaining total knee replacement the tibial attachment of the PCL is often removed.

The role of modular tibial implants in total knee replacement is not fully defined. We performed a prospective randomised controlled clinical trial using radiostereophotogrammetric analysis to compare the performance of an all-polyethylene tibia with a metal-backed cruciate-retaining condylar design, PFC-∑ total knee replacement for up to 24 months. There were 51 patients who were randomised into two treatment groups. There were 10 subsequent withdrawals, leaving 21 all-polyethylene and 20 metal-backed tibial implants. No patient was lost to follow-up. There were no significant demographic differences between the groups. At two years one metal-backed implant showed migration > 1 mm, but no polyethylene implant reached this level. There was a significant increase in the SF-12 and Oxford knee scores after operation in both groups.

In an uncomplicated primary total knee replacement the all-polyethylene PFC-∑ tibial prosthesis showed no statistical difference in migration from that of the metal-backed counterpart. There was no difference in the clinical results as assessed by the SF-12, the Oxford knee score, alignment or range of movement at 24 months, although these assessment measures were not statistically powered in this study.

We investigated the three-dimensional morphological differences of the articular surface of the femoral trochlea in patients with recurrent dislocation of the patella and a normal control group using three-dimensional computer models.

There were 12 patients (12 knees) and ten control subjects (ten knees). Three-dimensional computer models of the femur, including the articular cartilage, were created. Evaluation was performed on the shape of the articular surface, focused on its convexity, and the proximal and mediolateral distribution of the articular cartilage of the femoral trochlea. The extent of any convexity, and the proximal distribution of the articular cartilage, expressed as the height, were shown by the angles about the transepicondylar axis. The mediolateral distribution of the articular cartilage was assessed by the location of the medial and lateral borders of the articular cartilage.

The mean extent of convexity was 24.9° sd 6.7° for patients and 11.9° sd 3.6° for the control group (p < 0.001). The mean height of the articular cartilage was 91.3° sd 8.3° for the patients and 83.3° sd 7.7° for the control group (p = 0.03), suggesting a wider convex trochlea in the patients with recurrent dislocation of the patella caused by the proximally-extended convex area. The lateral border of the articular cartilage of the trochlea in the patients was more laterally located than in the control group.

Our findings therefore quantitatively demonstrated differences in the shape and distribution of the articular cartilage on the femoral trochlea between patients with dislocation of the patella and normal subjects.

Animal studies have shown that implanted anterior cruciate ligament (ACL) grafts initially undergo a process of revascularisation prior to remodelling, ultimately increasing mechanical strength. We investigated whether minimal debridement of the intercondylar notch and the residual stump of the ruptured ACL leads to earlier revascularisation in ACL reconstruction in humans. We undertook a randomised controlled clinical trial in which 49 patients underwent ACL reconstruction using autologous four-strand hamstring tendon grafts. Randomised by the use of sealed envelopes, 25 patients had a conventional clearance of the intercondylar notch and 24 had a minimal debridement method. Three patients were excluded from the study. All patients underwent MR scanning postoperatively at 2, 6 and 12 months, together with clinical assessment using a KT-1000 arthrometer and International Knee Documentation Committee (IKDC) evaluation. All observations were made by investigators blinded to the surgical technique. Signal intensity was measured in 4 mm diameter regions of interest along the ACL graft and the mid-substance of the posterior cruciate ligament.

Our results indicate that minimal debridement leads to earlier revascularisation within the mid-substance of the ACL graft at two months (paired t-test, p = 0.002). There was a significant reduction of mid-substance signal six months after the minimal debridement technique (paired t-test, p = 0.00007). No statistically significant differences were found in tunnel placement, incidence of Cyclops lesions, blood loss, IKDC scores, range of movement or Lachman test between the two groups.

We used single-photon emission computed tomography (SPECT) to determine the long-term risk of degenerative change after reconstruction of the anterior cruciate ligament (ACL). Our study population was a prospective series of 31 patients with a mean age at injury of 27.8 years (18 to 47) and a mean follow-up of ten years (9 to 13) after bone-patellar tendon-bone reconstruction of the ACL. The contralateral normal knee was used as a control. All knees were clinically stable with high clinical scores (mean Lysholm score, 93; mean Tegner activity score, 6). Fifteen patients had undergone a partial meniscectomy and ACL reconstruction at or before reconstruction of their ACL.

In the group with an intact meniscus, clinical symptoms of osteoarthritis (OA) were found in only one patient (7%), who was also the only patient with marked isotope uptake on the SPECT scan compatible with OA. In the group which underwent a partial meniscectomy, clinical symptoms of OA were found in two patients (13%), who were among five (31%) with isotope uptake compatible with OA. Only one patient (7%) in this group had evidence of advanced OA on plain radiographs.

The risk of developing OA after ACL reconstruction in this series is very low and lower than published figures for untreated ACL-deficient knees. There is a significant increase (p < 0.05) in degenerative change in patients who had a reconstruction of their ACL and a partial meniscectomy compared with those who had a reconstruction of their ACL alone.

We used three-dimensional movement analysis by computer modelling of knee flexion from 0° to 50° in 14 knees in 12 patients with recurrent patellar dislocation and in 15 knees in ten normal control subjects to compare the in vivo three-dimensional movement of the patella. Flexion, tilt and spin of the patella were described in terms of rotation angles from 0°. The location of the patella and the tibial tubercle were evaluated using parameters expressed as percentage patellar shift and percentage tubercle shift. Patellar inclination to the femur was also measured and patellofemoral contact was qualitatively and quantitatively analysed.

The patients had greater values of spin from 20° to 50°, while there were no statistically significant differences in flexion and tilt. The patients also had greater percentage patellar shift from 0° to 50°, percentage tubercle shift at 0° and 10° and patellar inclination from 0° to 50° with a smaller oval-shaped contact area from 20° to 50° moving downwards on the lateral facet.

Patellar movement analysis using a three-dimensional computer model is useful to clearly demonstrate differences between patients with recurrent dislocation of the patella and normal control subjects.

This prospective study used magnetic resonance imaging to record sagittal plane tibiofemoral kinematics before and after anterior cruciate ligament reconstruction using autologous hamstring graft. Twenty patients with anterior cruciate ligament injuries, performed a closed-chain leg-press while relaxed and against a 150 N load. The tibiofemoral contact patterns between 0° to 90° of knee flexion were recorded by magnetic resonance scans. All measurements were performed pre-operatively and repeated at 12 weeks and two years.

Following reconstruction there was a mean passive anterior laxity of 2.1 mm (sd 2.3), as measured using a KT 1000 arthrometer, and the mean Cincinnati score was 90 (sd 11) of 100. Pre-operatively, the medial and lateral contact patterns of the injured knees were located posteriorly on the tibial plateau compared with the healthy contralateral knees (p = 0.014), but were no longer different at 12 weeks (p = 0.117) or two years postoperatively (p = 0.909). However, both reconstructed and healthy contralateral knees showed altered kinematics over time. At two years, the contact pattern showed less posterior translation of the lateral femoral condyle during flexion (p < 0.01).

We performed a prospective, randomised controlled trial of unicompartmental knee arthroplasty comparing the performance of the Acrobot system with conventional surgery. A total of 27 patients (28 knees) awaiting unicompartmental knee arthroplasty were randomly allocated to have the operation performed conventionally or with the assistance of the Acrobot. The primary outcome measurement was the angle of tibiofemoral alignment in the coronal plane, measured by CT. Other secondary parameters were evaluated and are reported.

All of the Acrobot group had tibiofemoral alignment in the coronal plane within 2° of the planned position, while only 40% of the conventional group achieved this level of accuracy. While the operations took longer, no adverse effects were noted, and there was a trend towards improvement in performance with increasing accuracy based on the Western Ontario and McMaster Universities Osteoarthritis Index and American Knee Society scores at six weeks and three months. The Acrobot device allows the surgeon to reproduce a pre-operative plan more reliably than is possible using conventional techniques which may have clinical advantages.