Chronic dislocation of the patella is a rare condition usually congenital, but it can also be acquired. When neglected, leads to progressive genus valgus and external tibial torsion with subsequent secondary gonarthrosis.
We present the clinical case of a 71 year old male patient, retired. He had been submitted to a supra-patellar realignment surgery at the age of 13 (Campbell's operation), due to a recurrent dislocation of the patella, with dislocation recurrence, which ended up becoming permanent.
The patient presented with a sustained dislocation of the patella along the knee mobility arch, with active joint mobility from 0 to 90º. There was limited patella excursion, with reduction of the patella possible by manual traction.
Radiographically, he presented tricompartmental gonarthrosis, hypoplasia of the external condyle and dislocation of the patella.
The Computed Tomography study showed a 37mm TA-GT, with a 57º patellar tilt.
After discussion, it was proposed to a Total Knee Arthroplasty (TKA) with realignment of the extensor apparatus.
The literature on the topic of TKA in patients with gonarthrosis associated with permanent dislocation of the patella is scarce, as well as the case reports of patients with this condition.
There are few case reports, but they showed that the subvastus pathway associated with lateral release is a valid option for TKA, which allows the correction of deformities in valgus and gives a good patellar excursion.
The patient showed satisfactory results. He is currently 4 years after the operation, without pain, with a good alignment and with normal patellar tracking.

A new device-the PERSEUS™ is used to make the first distal femur coronal cut in Total Knee Arthroplasty(TKA).It is attached to the femur and connected via Bluetooth to an iPad.Movements at the hip orient the device to the femoral mechanical axis.The iPad then guides the correct placement of the cutting block over this device.Extramedullary cuts and use of this inertial mechanism theoretically lead to lower blood loss and better alignment respectively.We randomised 46 patients into 21 receiving TKA using the Perseus device and 25 receiving a conventional TKA. All patients were prospectively followed up at 6 weeks , 3 months and at a final follow up before unmasking (mean 14.2 months).Clinical parameters measured were mean drained output post-operatively, drop in haemoglobin concentration and patient reported scoring systems- Western Ontario and McMaster Universities Osteoarthritis Index(WOMAC), Knee Society Score(KSS) and Visual Analogue Score(VAS).Radiologically, the Hip Knee Ankle (HKA) axis was measured individually for both knees before and after surgery on full length lower limb radiographs. The Perseus group showed a significantly better radiological alignment post operatively.Results were consistent as only 19% of these values deviated beyond three degrees of neutral HKA axis as compared to 56 % of values in the control group.The group also showed a significantly lower drain output(p=0.011). WOMAC KSS and VAS scores were significantly better at final follow up. Considering the ease of use and absence of complications associated with other computer assisted navigation systems, this device could be an effective alternative to improve patient outcomes after TKA.

The aim of the current study was to identify normative variants of distal femur shaft anatomy that could be used to improve rotating hinge knee implant fixation. We also aimed to quantify the relationship between distal femur shaft anatomy and rotating hinge implant failure. A total of 200 patients who received standardized anteroposterior (AP) and lateral views of the knee joint were included in this study. On AP radiographs, we measured the distance between inner diameter of the femur at 20 cm proximally from the knee and at a point 2 cm proximally from the adductor tubercle. The ratio of the inner diameter of the femoral canal at 20 cm proximal of knee joint to the inner diameter of medullary canal at 2cm proximal of adductor tubercle was used as a novel index ratio. Two oberservers blindly and independently reviewed the radiographs twice. We applied the novel classification system to our previous described group of 33 aseptic loosening and 30 control cases of primary rotating hinge prosthesis. We found a higher incidence of implant failure in type C cases according to the novel classification (OR 23.99).
Three groups of anatomical classification can be constructed for each sex according to the 25th and 75th percentiles. The novel classification presents three different types of the knee joint for male and female patients. Type C has a wider inner diaphyseal diameter and had a higher risk for aseptic loosening following rotating hinge prosthesis compared to Type A with a narrower inner diaphyseal diameter.

Introduction: Unicompartmental knee arthroplasty (UKA) has higher revision rates compared to total knee arthroplasty (TKA) and is most often associated with alterations of mechanical forces that lead to osteoarthritis progression and aseptic loosening. The Medial UKA Knee Classification System (MUKA KCS) is an algorithm developed to improve UKA medial compartment implant survivorship. We sought to develop UKA guidelines for tibial resurfacing by establishing the face validity of the MUKA KCS and reporting its short-term outcomes. Methods: This was a single-center study of 500 patients who underwent MUKA between 2007 and 2013. 212 patients had measurements recorded radiographically. Univariate analysis with one-way ANOVA and post-hoc Tukey tests were performed. Results: Of 212 patients, 47 (22.2%), 71 (33.5%), 94 (44.3%) had Type 1, Type 2, and Type 3 knees based on the MUKA KCS, respectively. Preoperative valgus-stressed extension difference and stress view space were the highest in Type 3 knees, followed by Type 2 and then Type 1 (p≤0.012 for all pairwise comparisons), but preoperative unstressed extension difference was comparable across all types (p=0.184). Postoperative stressed extension differences did not differ between MUKA KCS types (p=0.32). Conclusions: The MUKA KCS classified knees undergoing MUKA into one of three types with statistically significant differences in valgus stress-view preoperative measurements. No significant differences in immediate surgical outcome were found between Knee Types. The results overall support the MUKA KCS in its ability to generate distinct knee classifications that determine the appropriate bone resurfacing protocol.

Objectives: The debate remains as to whether high tibial osteotomy (HTO) or unicompartmental knee replacement (UKA) is more beneficial for the treatment of unicompartmental osteoarthritis of the knee. The aim of this study is to compare the functional results, knee scores, activity levels and complications between the two procedures.

Materials and methods: All studies comparing functional results, postoperative complications, total knee arthroplasty revision rate, joint mobility and weight bearing will be evaluated with the different scores in patients with medial osteoarthritis of the knee. knee treated with HTO or UKA were included.

Results: Numerous studies and partially controversial results have been published. But very few randomized controlled studies looking at the impact of the two methods on the treatment of medial knee osteoarthritis were found (13 articles included in this study)

Discussion: No significant difference between the two groups was noted with regard to the walking distance, the functional scores of the knee, deterioration of the contralateral or patellofemoral compartment, the rate of revision and total knee arthroplasty. However, UKA produced better results compared to HTO in terms of functional results, assessment of pain and complications, although patients who underwent HTO tended to have slightly better range of motion.

Conclusion: Our study did not find a significant difference in the evolution of patients between the 2 groups and we believe that the both techniques are effective as long as they respect their own indications

Introduction: Recruitment challenges faced previous attempts at randomised controlled trials investigating supracondylar periprosthetic femoral fractures. There is a need for a multicentre cross-sectional study to help obtain an overview of the problem. Methods: A multicentre cross-sectional study was conducted in accordance with the RECORD statement . The aims were to evaluate the annual incidence of supracondylar periprosthetic femoral fractures proximal to total knee arthroplasty and to evaluate the types of surgical options employed in the management of such fractures. Results: During the study period of 1 year there were a total of 58 peri-prosthetic femoral fractures above total knee replacement across 7 centres in the United Kingdom. 69% (n=40) were females, mean age was 8110 years. 45 (81%) were treated surgically, time to surgical fixation was a median 2 days IQR(1-3) with 13.6% waiting 5days. Time from index TKA was a mean 8.96 years. Implant loosening was only present in n=2(3.4%) of cases. Adjusting for arthroplasty volume and population size the incidence of fractures was 1.8%. They accounted for 0.2% of orthopaedic emergency admissions. There was no statistically significant relationship between types of fracture and time from index TKA or time to surgery P=0.462 and P=0.302 respectively. Fracture fixation method did not influence time to surgery P=0.115. Conclusions: The present study provides accurate estimation of annual incidence for an entire region. Most of these fractures occurred in later life of otherwise well-functioning implants. Community equipoise in treatment selection prevails. Hence, the need for higher level studies is still justified.

Total knee replacement is a reliable operation for reducing pain and improving function in severe osteoarthritis of the knee. As incidence of obesity is increasing worldwide, there is a debate about the role of Body Mass Index (BMI) in selection of patients requiring total knee replacement. The aim of the study was to evaluate the impact of body mass index on total knee replacement in terms of post-operative improvement in knee range of motion, patient satisfaction and complications.Materials and Methods: Out of 175 patients who suffered from advance knee osteoarthritis and were candidates for primary total knee replacement from January 2016 to March 2018, 155 patients fit the inclusion criteria. Group 1 included 66 patients who were overweight and class 1 obese while group 2 included 89 patients who were class 2 and 3 obese according to WHO BMI classification. All patients underwent total knee replacement according to the hospital guidelines. Pre and post-operative range of motion, patient satisfaction and complications were assessed and documented. Results: There was no statistically significant difference in improvements in post-operative knee range of motion between the two groups up to 2 years of follow up [Mann-Whitney U test p= 0.069]. Similarly, Mann-Whitney U test showed that there is no significant difference between patient satisfaction levels (SF-12 scores) of the two groups (p=0.09). Conclusion: There is no significant impact of obesity on outcomes after total knee replacement and BMI should not be used as a factor in selecting patients who qualify for total knee replacement.