Aims

The aims of this study were to compare the diagnostic test characteristics of ultrasound alone, metal artefact reduction sequence MRI (MARS-MRI) alone, and ultrasound combined with MARS-MRI for identifying intra-operative pseudotumours in metal-on-metal hip resurfacing (MoMHR) patients undergoing revision surgery.

Introduction

Solid or cystic pseudotumour is a potentially destructive complication of metal on metal (MoM) couples, usually needing revision surgery. However, complete clearance of the pseudotumour is unlikely at times. This prospective case-controlled study reports cases which had recurrence after revision surgery for pseudotumour related to metal on metal hip couples.

Introduction

Tissue diagnosis is essential to direct the definitive management of a suspected soft tissue or bone sarcoma tissue. Knowledge of both the diagnostic yield and accuracy of core needle biopsies is therefore important to give the investigating team information on the likelihood of their initial investigations achieving a diagnosis.

If the lower re-rupture in operative treated patients was an effect of tendon-end apposition, then patients in whom that could be demonstrated in equinus by ultrasound could be equally well treated non-operatively without the attendant surgical risk.

All patients undergoing ultrasound for a suspected Achilles tendon repair between January 2000-2005 were included. Patients with a residual gap, 5mm or more in equinus; were treated by surgical repair. Those with a gap of less than 5mm were treated non-operatively. We excluded patients with no rupture, partial rupture and musculo-tendinuous junction (MTJ) tears. We recorded the following: clinical findings, ultrasound measurements of tendon gap in neutral and equinus, distance of rupture from distal insertion, the treatment and complications. All patients were followed up to a minimum of 6 months.

156 patients were treated for a clinical Achilles tendon rupture during the study period. We excluded 5 patients with no rupture on ultrasound, 15 with a MTJ tear, 7 with a muscle tear and 4 patients did not follow the protocol. 125 patients comprising 88 males and 37 females were entered into the study. 67 patients were treated operatively (37 open, 30 percutaneous) and 58 non-operatively. There was no significant difference between the 2 groups with respect to age, sex and injury mechanism. Two patients in the non-operative group had a re-rupture (3.4%) compared with 1 (1.5%) in the non-operative group. There were 2 incidences of superficial wound infection and 2 of temporary dorsal foot numbness in the operative. One patient in the non-operative group had a DVT. There was no significant difference for any of the complications between the two groups.

It may be possible to reduce the risk of re-rupture and surgery using dynamic ultrasound to determine which treatment the patient receives.

Patella subluxation assessed on dynamic MRI has previously been shown to be associated with anterior knee pain. In this MRI study of 60 patients we investigated the relationship between subluxation and multiple bony, cartilaginous and soft-tissue factors that might predispose to subluxation using discriminant function analysis.

Patella engagement (% of patella cartilage overlapping with trochlea cartilage) had the strongest relationship with subluxation. Patellae with > 30% engagement tended not to sublux; those with < 30% tended to sublux. Other factors that were associated with subluxation included the tibial tubercle-trochlea notch distance, vastus medialis obliquus distance from patella, patella alta, and the bony and cartilaginous sulcus angles in the superior part of the trochlea. No relationship was found between subluxation and sulcus angles for cartilage and bone in the middle and lower part of the trochlea, cartilage thicknesses and Wiberg classification of the patella.

This study indicates that patella engagement is a key factor associated with patellar subluxation. This suggests that in patients with anterior knee pain with subluxation, resistant to conservative management, surgery directed towards improving patella engagement should be considered. A clinical trial is necessary to test this hypothesis.

Metal on metal hip resurfacing (MMHR) is a popular procedure for the treatment of osteoarthritis in young patients. Several centres have observed masses, arising from around these devices, we call these inflammatory pseudotumours. They are locally invasive and may cause massive soft tissue destruction. The aim of this study was to determine the incidence and risk factors for pseudotumours that are serious enough to require revision surgery.

In out unit, 1,419 MMHRs were performed between June 1999 and November 2008. All revisions were identified, including all cases revised for pseudotumour. Pseudotumour diagnosis was made by histological examination of samples from revision. A Kaplan-Meier survival analysis was performed, Cox regression analysis was used to estimate the independent effects of different factors.

The revision rate for pseudotumour increased with time and was 4% (95% CI: 2.2% to 5.8%) at eight years. Female gender was a strong risk factor: at eight years the revision rate for pseudotumours in men was 0.5% (95% CI 0% to 1.1%), in women over 40 it was 6% (95% CI 2.3% to 10.1%) and in women under 40 it was 25% (95% CI 7.3% to 42.9%) (p< 0.001). Other factors associated with an increase in revision rate were, small components (p=0.003) and dysplasia (p=0.019), whereas implant type was not (p=0.156).

We recommend that resurfacings are undertaken with caution in women, especially those younger than 40 years of age, but they remain a good option in men. Further work is required to understand the patho-aetiology of pseudotumours so that this severe complication can be avoided.

Introduction: Symptomatic abnormal soft-tissue masses relating to the hip joint, such as those described as pseudotumours, are being increasingly reported following metal-on-metal hip resurfacing arthroplasty (MoMHRA). These were found to be locally destructive, requiring revision surgery in a high proportion (75%) of patients. Lymphocyte infiltrations seen in pseudotumours were similar to aseptic lymphocyte vascular associated lesion (ALVAL), which is thought to represent a T-lymphocyte-mediated delayed type hypersensitivity. Therefore, a delayed hypersensitivity reaction to nickel (Ni), chromium (Cr) or cobalt (Co) has been suggested to play a role in pseudotumour aetiology. In patients with bilateral MoMHRA who presented with symptoms on one side, subsequent scans have demonstrated pseudotumours both on the symptomatic and asymptomatic side. Thus, there are concerns that there may be an appreciable number of asymptomatic pseudotumours that surgeons are unaware of and these may eventually become symptomatic.

Aim: The aims of this study were:

to determine the prevalence of asymptomatic pseudotumours after MoMHRA; and

Methods: A total of 201 MoMHRA implanted hips in 158 patients (97 male, 61 female) with a mean age of 56 years (range 33–73 years) were evaluated. The mean follow-up was 61 months (range 13–88 months). Resurfacing devices implanted included 128 Birmingham Hip Resurfacing, 66 Conserve Plus and seven ReCap. The control groups included additional 20 patients, 10 male and 10 female (a mean age 68 years, range 57–80 years) with metal-on-polyethylene total hip arthroplasty and a further 22 age-matched patients (a mean age 55 years) without any metal implants. Ultrasound was used as the initial imaging modality and MRI was used to assess the extent of the identified masses. Patients with a soft-tissue mass had ultrasound-guided aspiration or core biopsy performed. Venous blood samples were collected in all patients for serum cobalt and chromium ion levels analysis using Inductively-Coupled Plasma Mass Spectrometer and lymphocyte transformation tests (LTT). The Oxford Hip Score (OHS) was used to measure the functional outcomes of patients. Acetabular component abduction angle was measured from standardised anteroposterior pelvis radiographs.

Results: Prevalence – Pseudotumours were found in 7 patients (6 female and 1 male). The overall prevalence of asymptomatic pseudotumours was 4%, with a relatively very high (30%) prevalence in females with bilateral implants. Histological examinations showed extensive necrosis of connective tissue, in which there were scattered aggregates of metal particles and a diffuse lymphocyte infiltrate.

Metal Ion Levels – The presence of pseudotumour was associated with significantly higher median serum cobalt levels (9.2mg/L vs. 1.9mg/L, p< 0.001), chromium levels (12.0mg/L vs. 2.1mg/L, p< 0.001), hip aspirate cobalt levels (1182 mg/L vs. 86.2mg/L, p=0.003), and aspirate chromium levels (883mg/L vs. 114.8mg/ L, p=0.006), as well as with inferior functional scores (OHS 41 vs. 47 p< 0.001). There was no significant difference in acetabular cup inclination angle (p=0.51). Lymphocyte Reactivity: A higher incidence and level of enhanced lymphocyte reactivity to Ni (p=0.001), but not to Co or Cr (the principal elements in the CoCr alloy used in metal-on-metal hip resurfacing implants), was found in patients with MoMHRA compared to the patients without MoM implants. However, lymphocyte reactivity to Co, Cr and Ni did not significantly differ in patients with pseudotumours compared to those patients without pseudotumours.

Conclusion: The prevalence of asymptomatic pseudotumours in females was high, especially in females with bilateral MoMHRA implants (30%). The patients with ‘asymptomatic’ pseudotumours were in fact mildly symptomatic. Lymphocyte reactivity to Co, Cr and Ni did not differ in patients with pseudotumour compared to those patients without pseudotumours, suggesting that systemic hypersensitivity type IV reactions, mediated by lymphocyte reactivity to these metals, is not the dominant mechanism in pathogenesis of the soft tissue pseudotumours. Furthermore, pseudotumours were not detected in those patients who had normal levels of cobalt and chromium ions. This suggests that pseudotumours do not occur if MoM articulations are well functioning. Therefore, pseudotumours are likely to be a biological consequence of the large amount of metal debris generated in vivo due to excessive wear.

Introduction: This study explores whether modern magnetic resonance imaging (MRI) with improved cartilage sequencing is able to show a more detailed view of antero-medial osteoarthritis of the knee (AMOA) than previously, so enabling a radiographic description of this common phenotype of disease. Modern MRI technology allows us to visualize in great detail the structures and cartilage within the knee, providing a better understanding of the pathoanatomy of AMOA. This description of the end stage of disease is useful as a baseline when investigating the progression of arthritis through the knee. Preoperative assessment of patients and selection of intervention is very important and preoperative imaging forms an integral part of this. This will also be useful in preoperative assessment and surgical management of patients.

Methods: 50 patients with a radiographic diagnosis of anteromedial osteoarthritis of the knee and had been listed for unicompartmental knee arthroplasty (UKA) had MRI as part of their pre-op workup. At operation all were deemed suitable for UKA using the current Oxford indications. The image sequences were coronal, axial and sagittal with a predetermined cartilage protocol. The state of the ACL, cartilage wear degree and location, presence and pattern of osteophytes, meniscal anatomy and subchondral high signal were assessed.

Results: All the ACLs were visualized and in continuity, however 40% showed intrasubstance high signal. 100% of medial compartments showed full thickness anteromedial loss with preservation of the posteromedial cartilage. When present, the meniscus was extruded in 75% of cases.

90% of lateral compartments were normal and none had full thickness cartilage loss. However 10% showed high signal in the tibial plateau. There was a highly reproducible pattern of osteophyte formation; 94% posteromedial and posterolateral aspect of medial femoral condyle; 90% medial tibial; 80% medial femoral and 84% lateral intercondylar notch.

Discussion: This study maps the pattern of anteromedial osteoarthritis using modern MRI techniques. This creates a baseline description of disease which is useful when investigating disease progression. This also has importance in determining preoperative indications (preservation of ACL and posteromedial cartilage); surgical technique (determine pattern of osteophytes requiring resection) and potentially important for long-term outcome (early lateral compartment changes).

Recently, a series of locally destructive soft tissue pseudotumour has been reported in patients following metal-on-metal hip resurfacing arthroplasty (MoMHRA), requiring revision surgery in a high percentage of patients. Based on the histological evidence of lymphocytic infiltration, a delayed hypersensitivity reaction to nickel (Ni), chromium (Cr) or cobalt (Co) has been suggested to play a role in its aetiology. The aim of this study was to investigate the incidence and level of hypersensitivity reaction to metals in patients with pseudotumour.

Materials and Methods: 25 patients were investigated in this Ethics approved study:

Group 1: MoMHRA patients with pseudotumours, detected on the ultrasound and confirmed with MRI (n=6, 5 F:1 M, mean age 53 years);

Lymphocyte transformation tests (LTT) were used to measure lymphocyte proliferation responses to metals. Peripheral blood mononuclear cells were isolated from heparinized blood samples using standard Ficoll–Hypaque® (Pharmacia). The PBMC were cultured at a cell density of 106 cells/mL. Culture was set up in the presence of either:

medium alone;

After 5 days of culture, cells were pulsed with [3H]-thymidine and proliferation was assessed by scintillation counting. The stimulation index (SI) was calculated by the ratio of mean counts per minute of stimulated to unstimulated cultures. A SI value of greater than 2.0 was interpreted as a positive result.

Results: A clinical history of metal allergy was reported in 2/6 in Group 1, 2/13 in Group 2, and none in Group 3. In pseudotumour group, the incidence of reactivity to Ni, Co and Cr was 60%, 17% and 0%, respectively. Within Group 2, the reactivity to Ni, Co and Cr was 69%, 8% and 15%, respectively. One control subject had reactivity to Ni. Inter-group comparisons of mean SI values (Kruskal-Wallis non-parametric analysis of variance) showed no significant differences (p> 0.05).

Discussion: The incidence of enhanced lymphocyte response to metals in patients with MoMHRA was more common than the control group. However, in comparison with non-pseudotumour patients, there was no significant difference in the incidence or the level of lymphocyte reactivity in patients with pseudotumour. We conclude that patients with MoMHRA have an enhanced lymphocyte response to metal ions, reflecting exposure and immune reactivity. However, patients with pseudotumours have a similar proliferative response to those without pseudotumours, which suggests that type IV hypersensitivity may not be the cause of the pseudotumours.

Tribological studies of hip arthroplasty suggest that larger diameter metal-on-metal (MOM) articulations would produce less wear than smaller diameter articulations. Other advantages using these large femoral heads implants include better stability with lower dislocation rates and improved range of motion. The aim of the present study was to compare chromium (Cr), cobalt (Co) and titanium (Ti) ion concentrations up to 1-year after implantation of different large diameter MOM total hip arthroplasty (THA).

Methods: Cr, Co and Ti concentrations were measured using a high resolution mass spectrometer (HR-ICP-MS) by an independent laboratory in 110 patients, randomized to receive a large metal-on-metal articulation unce-mented Ti THA from one of the following companies: Zimmer, Smith & Nephew, Biomet or Depuy. Samples of whole blood were collected pre-operatively, and postoperatively at six months and one year.

Summary of Results: At 6 months, whole blood cobalt levels were: (table removed)

Statistical group comparison revealed significant difference for Cr (p=0.006), Co (p=0.047) and Ti (p=< 0.001). With Biomet implants presenting the best results for Cr and Co and Zimmer the highest Ti level.

Discussion: Different implant factors may influence measured metal ion level in whole blood: articular surface wear and implant passive corrosion. Bearing wear may be related to its diameter, quality of the surface finish, component sphericity, radial clearance, manufacturing process (forged vs cast metal) and metal carbon content. Biomet articulation seems to present the best factors selection. Passive corrosion of exposed metallic surfaces is represented by the elevated Ti levels found in all tested systems (Ti was not part of the bearing surfaces). The plasma sprayed acetabular component surface of the Zimmer’s component seems to be responsible for the significant difference in Ti versus the other implants.

Patello-femoral instability (PFI) affects 40 individuals per 100,000 population and causes significant morbidity. The causes of patello-femoral instability are multi-factorial, and an isolated anatomical abnormality does not necessarily indicate instability. Patello-femoral subluxation ranges from 0% (stable patella tracking) to 100% (dislocation) and there is an established relationship between the amount of subluxation and anterior knee pain. Traditionally, magnetic resonance (MR) imaging and standard radiographs are used to guide the clinician towards a suitable corrective procedure for PFI. The multi-factorial nature of patello-femoral instability is not addressed with current imaging techniques. This study aims to address which anatomical variables assessed on MR images are most relevant to patello-femoral subluxation. This information will aid surgical decision making, particularly in selecting the most appropriate reconstructive surgery.

A retrospective analysis of MR studies of 60 patients with suspected patello-femoral instability was performed. All patients were graded for degree of subluxation using a dynamic MR scan.

The patient scans were assessed for the presence of a specific range of anatomical variables:

patella alta, (modified Insall-Salvatti)

The Wilk’s Lambda test for multi-variate analysis was used to establish whether any relationship was present between the degree of patello-femoral instability and bony or soft tissue anatomical variables. Non-parametric statistical tests were applied across the groups and within the groups to assess their relative significance.

The following variables showed a significant relationship with patellofemoral subluxation; distance of the VMO from the patella (< 0.001), TTD (< 0.001), patella engagement (0.001), sulcus angles (0.004) and patella alta (0.005).

This study agrees with previous work showing a significant correlation between subluxation and trochlea sulcus angle and TTD.

This is the first study to establish a significant correlation between patella engagement and radiological instability. The lower the percentage engagement of the patella in the trochlea, the greater the degree of patello-femoral instability. Patella engagement showed a more significant relationship with subluxation than patella alta.

We report a new method of predicting patello-femoral instability by measuring the overlap of the patella in the trochlea groove.

Introduction: Patellofemoral joint subluxation is associated with pain and dysfunction. The causes of patel-lofemoral subluxation are poorly understood and multi-factorial, arising from abnormalities of both bone and soft tissues. This study aims to identify which anatomical variables assessed on Magnetic Resonance (MR) images are most relevant to patellofemoral subluxation.

Method: A retrospective analysis of MR studies of 60 patients with suspected patellofemoral subluxation was performed. All patients were graded for the severity/ magnitude of radiological subluxation using a dynamic MR scan (Grade 0 [nil] to Grade 3 [subluxed]. The patient scans were assessed using a range of anatomical variables, these included:

Patella alta,

Results: The distance of the VMO from the patella (p < 0.001), TTD (p < 0.001) and Patella Engagement (p < 0.001) showed highly significant relationships with patellofemoral subluxation.

Conclusions: The following three anatomical variables are associated with patellofemoral subluxation: the distance of the VMO muscle from the patella, TTD and Patella Engagement.

This is the first study to establish that patella engagement is related to PFJ subluxation showing that the lower the percentage engagement of the patella in the trochlea, the greater the severity/magnitude of patellofemoral subluxation. The finding provides greater insight into the aetiology and understanding of the mechanism of symptomatic PFJ subluxation.

Introduction: Despite the satisfactory short-term implant survivorship of MoM hip resurfacing arthroplasty, symptomatic abnormal periprosthetic soft-tissue masses relating to the hip joint, ‘pseudotumours’, are being increasingly reported. These were found be locally destructive, requiring revision surgery in 75% of patients. Asymptomatic pseudotumours have not been previously investigated.

Methods: The aims were: (1) to investigate the prevalence of asymptomatic pseudotumours; and (2) to investigate their potential association with the level of metal ions. A total of 160 hips in 123 patients with a mean age 56 years (range 33–73) were evaluated at a mean follow-up of 61 months (range 13–88). Radiographs and OHS were assessed. Patients with a cystic or solid mass detected on the ultrasound/MRI had an aspiration or biopsy performed. Cobalt and chromium levels were analysed using Inductively-Coupled Plasma Spectrometer.

Results: Pseudotumours were found in 6 patients (5F: 1M). In 80% of bilateral cases, it was found in both sides. Histological examination showed extensive necrosis and diffuse lymphocyte infiltration. The presence of pseudotumour was associated with higher serum cobalt (9.2 μg/L vs. 1.9μg/L, p< 0.001) and chromium levels (12.0μg/L vs. 2.1μg/L, p< 0.001); higher hip aspirate cobalt (1182 μg/L vs. 86.2μg/L, p=0.003) and chromium levels (883μg/L vs. 114.8μg/L, p=0.006); and with inferior OHS (23 vs. 14 p=0.08).

Discussion: The prevalence of asymptomatic pseudotumour (5%) was higher than previously reported for the symptomatic pseudotumours (1%). There was a sixfold elevation of serum and a twelve-fold elevation of hip aspirate levels of cobalt and chromium in patients with pseudotumours. This suggests that pseudotumours may be a biological consequence of the large amount of metal debris generated in vivo. The association between pseudotumour and elevated metal ion levels might theoretically be explained by either systemic hypersensitivity responses to metal ions or local cytotoxic effects due to a high level of metal ions.

Introduction: This study explores whether modern magnetic resonance imaging (MRI) with improved cartilage sequencing is able to show a more detailed view of anteromedial osteoarthritis of the knee (AMOA). Preoperative assessment of patients and selection of intervention is very important and preoperative imaging forms an integral part of this. Modern MRI technology may allow us to visualize in great detail the structures and cartilage within the knee, providing a better understanding of the pathoanatomy of AMOA. This will be useful in preoperative assessment and surgical management of patients.

Methods: 50 patients with a radiographic diagnosis of anteromedial osteoarthritis of the knee and had been listed for unicompartmental knee arthroplasty (UKA) had MRI as part of their pre-op workup. At operation all were deemed suitable for UKA using the current Oxford indications. The image sequences were coronal, axial and sagittal with a predetermined cartilage protocol. The state of the ACL, cartilage wear location and pattern, presence of osteophytes and subchondral high signal were assessed.

Results: All the ACLs were visualized and in continuity, however 40% showed intrasubstance high signal.

100% of medial compartments showed full thickness anteromedial loss with preservation of the posteromedial cartilage. When present, the meniscus was extruded in 96% of cases.

Discussion: This study maps the pattern of anteromedial osteoarthritis using modern MRI techniques. This has importance in determining preoperative indications (preservation of ACL and posteromedial cartilage); surgical technique (determine pattern of osteophytes requiring resection) and potentially important for long-term outcome (early lateral compartment changes).

We report on a group of 20 metal-on-metal resurfaced hips (17 patients) presenting with a soft tissue mass associated with various symptoms. We describe these masses as pseudotumours.

All patients underwent plain radiography and fuller investigation with CT, MRI and ultrasound. Where samples were available, histology was performed. All patients in this series were female. Presentation was variable; the most common symptom was pain or discomfort in the hip region. Other symptoms included spontaneous dislocation, nerve palsy, an enlarging mass or a rash. The common histological features were extensive necrosis and lymphocytic infiltration. Fourteen of the 20 cases (70%) have so far required revision to a conventional hip replacement and their symptoms have either settled completely or improved substantially since the revision surgery. Two of the three bilateral cases have asymptomatic pseudotumours on the opposite side.

We estimate that about 1% of patients develop a pseudotumour in the first five postoperative years after a hip resurfacing. The cause of these pseudotumours is unknown and is probably multi-factorial, further work is required to define this; they may be manifestations of a metal sensitivity response. We are concerned that with time the incidence of these pseudotumours will increase.

Introduction: We report on a group of 20 metal-on-metal resurfaced hips (17 patients) presenting with a soft tissue mass associated with various symptoms; these masses we termed pseudotumours. All patients underwent plane radiography; CT, MRI and ultrasound investigations were also performed for some patients. Where samples were available histology was performed.

Methods: All patients in this series were female. Presentation was variable; the most common symptom was pain or discomfort in the hip region. Other symptoms included spontaneous dislocation, nerve palsy, a noticeable mass or a rash. The common histological features were extensive necrosis and lymphocytic infiltration. Fourteen of the 20 cases (70%) have so far required revision to a conventional hip replacement and their symptoms have either settled completely or improved substantially since the revision surgery. Two of the three bilateral cases have asymptomatic pseudotumours on the opposite side.

Conclusions: We estimate that about 1% of patients develop a pseudotumour in the first five postoperative years after a hip resurfacing. The cause of these pseudotumours is unknown and is probably multi-factorial, further work is required to define this; they may be manifestations of a metal sensitivity response. We are concerned that with time the incidence of these pseudotumours will increase.

Introduction: Acquired pes planus is caused by mechanical uncoupling of the bones of the tarsus due to failure of the osseoligamentous complex that maintains the medial longitudinal arch of the foot. The most common cause of acquired flat foot deformity in adults is posterior tibialis tendon dysfunction. A solitary previous case report has documented an alternative aetiology of acquired flat foot in adults due to isolated spring ligament rupture; in that case diagnosis was made intra-operatively.

Materials and Methods: We present 9 cases of acquired flat foot deformity that were caused by isolated spring ligament insufficiency, mainly presenting after an eversion injury of the ankle. We present the clinical sign of ability to single leg tiptoe, but with persistent forefoot abduction and heel valgus, that allows differentiation of this diagnosis from posterior tibialis tendon dysfunction. In addition we illustrate the radiological features of this condition which have not been previously described and allow confirmation of the diagnosis non-operatively.

Results: Six patients have been managed with orthotics and three underwent surgery; one patient who presented early had an isolated repair of the spring ligament complex and has done well. The remaining two patients required a calcaneal osteotomy and Flexor Digitorum Longus transfer as for a PTT reconstruction. In all these three patients the spring ligament was found to be completely ruptured during surgery.

Discussion: This type of injury may not be as rare as previously thought and demonstrates the importance of the spring ligament on its own in maintaining the medial longitudinal arch. Awareness of this condition could lead to earlier diagnosis and better prognosis with earlier treatment.

Conclusion: We propose that early diagnosis (with ultrasound confirmation) and management of this condition would offer a better prognosis and allow less interventional surgery.

Hypothesis: If the lower re-rupture in operative treated patients was an effect of tendon-end apposition, then patients in whom that could be demonstrated in equinus by ultrasound could be equally well treated non-operatively without the attendant surgical risk.

Method: All patients undergoing ultrasound for a suspected Achilles tendon repair between January 2000 – 2005 were included. Patients with a residual gap, 5mm or more in equinus; were treated by surgical repair. Those with a gap of less than 5mm were treated non-operatively. We excluded patients with no rupture, partial rupture and musculo-tendinuous junction (MTJ) tears. We recorded the following: clinical findings, ultrasound measurements of tendon gap in neutral and equinus, distance of rupture from distal insertion, the treatment and complications. All patients were followed up to a minimum of 6 months.

Results: 156 patients were treated for a clinical Achilles tendon rupture during the study period. We excluded 5 patients with no rupture, 15 with a MTJ tear, 7 with a muscle tear and 4 patients did not follow the protocol. 125 patients comprising 88 males and 37 females were entered into the study. 67 patients were treated operatively (37 open, 30 percutaneous) and 58 non-operatively. There was no significant difference between the 2 groups with respect to age, sex and injury mechanism. There were 2 re-ruptures in the non-operative group and 1 with surgery. The operative group had 2 patients with superficial wound infection and 2 with temporary dorsal foot numbness. One patient in the non-operative group had a DVT. There was no significant difference for any of the complications between the two groups.

Conclusions: It may be possible to reduce the risk of re-rupture and surgery using dynamic ultrasound to determine which treatment the patient receives.

We report 17 patients (20 hips) in whom metal-on-metal resurfacing had been performed and who presented with various symptoms and a soft-tissue mass which we termed a pseudotumour. Each patient underwent plain radiography and in some, CT, MRI and ultrasonography were also performed. In addition, histological examination of available samples was undertaken.

All the patients were women and their presentation was variable. The most common symptom was discomfort in the region of the hip. Other symptoms included spontaneous dislocation, nerve palsy, a noticeable mass or a rash. The common histological features were extensive necrosis and lymphocytic infiltration. To date, 13 of the 20 hips have required revision to a conventional hip replacement. Two are awaiting revision.

We estimate that approximately 1% of patients who have a metal-on-metal resurfacing develop a pseudotumour within five years. The cause is unknown and is probably multifactorial. There may be a toxic reaction to an excess of particulate metal wear debris or a hypersensitivity reaction to a normal amount of metal debris. We are concerned that with time the incidence of these pseudotumours may increase. Further investigation is required to define their cause.

The indications for unicompartmental knee arthroplasty (UKA) remain controversial; in particular the threshold of disease in the patellofemoral compartment is debated. Whilst some authorities ignore the condition of the patellofemoral joint, others consider pre-existing patellofemoral osteoarthritis (PFOA) a contra-indication to UKA. The aim of this study was to determine the influence of PFOA on the outcome of medial UKA.

This prospective study involved one hundred consecutive patients who had undergone cemented medial Oxford UKA (phase 3), via a minimally invasive approach, at least one year previously. Patients were divided into two groups according to the presence or absence of full thickness cartilage loss (FTCL) on the patella or trochlea at operation. A pre-operative skyline radiograph was graded using the Altman score, by an independent Musculoskeletal Radiologist. Outcome was evaluated with the Knee Society Score (AKSS) and the Oxford Knee Score (OKS, maximum 48). Groups were compared for differences in knee score and Altman grade using a one way ANOVA. Repeat analysis was performed using the presence of anterior knee pain (AKP) as the group defining variable.

There were 28 patients with FTCL, and both groups were well matched for age, gender and activity levels. Analysis showed no significant difference in post operative knee scores between groups with either the presence of FTCL or the presence of AKP pre-operatively as a factor. There was no significant difference in Altman grade between groups.

Intra-operative evidence of PFOA in patients with medial compartment osteoarthritis does not prejudice the outcome of UKA. Even the inclusion of patients with symptomatic AKP, without necessarily having PFOA, does not affect the outcome after UKA. These short results are encouraging, but longer follow up is required.