Tibial tuberosity-trochlear groove distance: does it measure up?

Recognized anatomic variations that lead to patella instability include patella alta and trochlea dysplasia. Lateralization of the extensor mechanism relative to the trochlea is often considered to be a contributing factor; however, controversy remains as to the degree this contributes to instability and how this should be measured. As the tibial tuberosity-trochlear groove (TT-TG) is one of most common imaging measurements to assess lateralization of the extensor mechanism, it is important to understand its strengths and weaknesses. Care needs to be taken while interpreting the TT-TG value as it is affected by many factors. Medializing tibial tubercle osteotomy is sometimes used to correct the TT-TG, but may not truly address the underlying anatomical problem. This review set out to determine whether the TT-TG distance sufficiently summarizes the pathoanatomy, and if this assists with planning of surgery in patellar instability. Cite this article: Bone Jt Open 2022;3(3):268-274.

The influence of patellofemoral stabilisation surgery on joint congruity: an MRI surface mapping study.

BACKGROUND: In the unstable patellofemoral joint (PFJ), the patella will articulate in an abnormal manner, producing an uneven distribution of forces. It is hypothesised that incongruency of the PFJ, even without clinical instability, may lead to degenerative changes. The aim of this study was to record the change in joint contact area of the PFJ after stabilisation surgery using an established and validated MRI mapping technique. METHODS: A prospective MRI imaging study of patients with a history of PFJ instability was performed. The patellofemoral joints were imaged with the use of an MRI scan during active movement from 0° through to 40° of flexion. The congruency through measurement of the contact surface area was mapped in 5-mm intervals on axial slices. Post-stabilisation surgery contact area was compared to the pre-surgery contact area. RESULTS: In all, 26 patients were studied. The cohort included 12 male and 14 female patients with a mean age of 26 (15-43). The greatest mean differences in congruency between pre- and post-stabilised PFJs were observed at 0-10 degrees of flexion (0.54 cm2 versus 1.18 cm2, p = 0.04) and between 11° and 20° flexion (1.80 cm2 versus 3.45 cm2; p = 0.01). CONCLUSION: PFJ stabilisation procedures increase joint congruency. If a single axial series is to be obtained on MRI scan to compare the pre- and post-surgery joint congruity, the authors recommend 11° to 20° of tibiofemoral flexion as this was shown to have the greatest difference in contact surface area between pre- and post-operative congruency.

Plate and screw fixation of arthroscopically assisted tibial tuberosity osteotomy: technique and results.

INTRODUCTION: We describe a fixation technique for tibial tuberosity osteotomies (TTO) utilising a plate and screw construct which adheres to established principles of bone healing. We record and discuss the complication profile and benefits of this technique. METHOD: The technique is outlined, and thirty consecutive case of TTO fixed with this combination of plate and screws were analysed during a study period from January 2018 to October 2018. All patients were followed up clinically to 3 months post-operation for the purpose of identifying early complications of surgery. Radiographic series were reviewed at 2, 6 and 12 weeks post-operation for evidence of fracture, loss of position, hardware failure and union. RESULTS: All cases went on to clinical and radiographic union by 12 weeks. We identified one case of hardware failure, one case of superficial infection and one case of stiffness requiring manipulation. CONCLUSION: We have found this technique of plate and screw construct to be effective in arthroscopically assisted TTO fixation leading to consistent union without loss of position with a low complication profile.

Does overstuffing of the patellofemoral joint in total knee arthroplasty have a significant effect on postoperative outcomes?

BACKGROUND: There is ongoing debate in the literature as to whether or not patellofemoral joint overstuffing has a clinically significant effect on postoperative outcomes following total knee arthroplasty (TKA). This study investigates the effect of patellofemoral joint overstuffing on patient-reported outcomes using novel methods of radiographic measurement. METHODS: The study population consisted of a prospective cohort of 266 patients receiving a Triathlon® (Stryker, Kalamazoo, MI, USA) TKA between 2006 and 2009. Participants completed the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) questionnaire preoperatively and at 12 months postoperatively. Pre- and postoperative radiographic measurements were taken according to a defined protocol to assess for patellofemoral overstuffing. Measurement reproducibility was assessed using inter-observer intraclass correlation coefficients. Associations between radiographic measurements and patient-reported outcomes were analysed using linear regression analysis. RESULTS: A total of 107 patients had adequate images and were included in the analysis for this study. Three different radiographic measurements were used to identify patellofemoral overstuffing all with good intra- and inter-observer reliability. There was no association identified between combined (patella and trochlea) patellofemoral overstuffing measurements and WOMAC scores. However, a statistically significant association was identified between an increase in anterior trochlear offset and worse knee pain and function scores (P < 0.05). CONCLUSIONS: There is no identifiable association between true patellofemoral overstuffing and clinical outcome; however, there is a small association with the anterior trochlear offset though further studies are warranted to confirm the clinical significance of this finding.

Repair of Torn Avascular Meniscal Cartilage Using Undifferentiated Autologous Mesenchymal Stem Cells: From In Vitro Optimization to a First-in-Human Study.

Meniscal cartilage tears are common and predispose to osteoarthritis (OA). Most occur in the avascular portion of the meniscus where current repair techniques usually fail. We described previously the use of undifferentiated autologous mesenchymal stem cells (MSCs) seeded onto a collagen scaffold (MSC/collagen-scaffold) to integrate meniscal tissues in vitro. Our objective was to translate this method into a cell therapy for patients with torn meniscus, with the long-term goal of delaying or preventing the onset of OA. After in vitro optimization, we tested an ovine-MSC/collagen-scaffold in a sheep meniscal cartilage tear model with promising results after 13 weeks, although repair was not sustained over 6 months. We then conducted a single center, prospective, open-label first-in-human safety study of patients with an avascular meniscal tear. Autologous MSCs were isolated from an iliac crest bone marrow biopsy, expanded and seeded into the collagen scaffold. The resulting human-MSC/collagen-scaffold implant was placed into the meniscal tear prior to repair with vertical mattress sutures and the patients were followed for 2 years. Five patients were treated and there was significant clinical improvement on repeated measures analysis. Three were asymptomatic at 24 months with no magnetic resonance imaging evidence of recurrent tear and clinical improvement in knee function scores. Two required subsequent meniscectomy due to retear or nonhealing of the meniscal tear at approximately 15 months after implantation. No other adverse events occurred. We conclude that undifferentiated MSCs could provide a safe way to augment avascular meniscal repair in some patients. Registration: EU Clinical Trials Register, 2010-024162-22. Stem Cells Translational Medicine 2017;6:1237-1248.

Results of medial patellofemoral ligament reconstruction compared with trochleoplasty plus individual extensor apparatus balancing in patellar instability caused by severe trochlear dysplasia: a systematic review and meta-analysis.

PURPOSE: Many studies have reported satisfactory clinical outcomes and low redislocation rates after reconstruction of the medial patellofemoral ligament (MPFL) for the treatment of lateral patellar instability. Despite uncorrected severe trochlear dysplasia (Dejour type B to D) being acknowledged as a major reason for less favourable clinical outcomes and a higher incidence of patellar redislocations after an isolated MPFL reconstruction, the evidence for a deepening trochleoplasty procedure remains scarce in the current literature. The hypothesis of this systematic review and meta-analysis was that a deepening trochleoplasty in combination with an a la carte extensor apparatus balancing procedure provides lower redislocation rates and superior clinical outcomes than isolated MPFL reconstruction in patients with lateral patellar instability caused by severe trochlear dysplasia. METHODS: A systematic review of the literature was conducted using specific inclusion and exclusion criteria for clinical studies reporting index operations (trochleoplasty and MPFL reconstruction) for the treatment of patellar instability caused by severe trochlear dysplasia. The Kujala score was analysed as the primary clinical outcome parameter in a random effects meta-analysis. RESULTS: Ten uncontrolled studies with a total of 407 knees (374 patients) were included in this analysis. The MPFL group comprised 4 studies with a total of 221 knees (210 patients), and the trochleoplasty group comprised 6 studies with a total of 186 knees (164 patients). The mean preoperative Kujala score ranged between 50.4 and 70.5 in the MPFL group and between 44.8 and 75.1 in the trochleoplasty group. The pooled Kujala score increased significantly by 26.4 (95% CI 21.4, 31.3; P < 0.00001) points in the MPFL group and by 26.2 (95% CI 19.8, 32.7; P < 0.00001) points in the trochleoplasty group. The post-operative patellar redislocation/subluxation rate was 7% in the MPFL group and 2.1% in the trochleoplasty group. CONCLUSION: This analysis found significant post-operative improvements in patient-reported outcomes for patients undergoing both an MPFL reconstruction and in those undergoing a trochleoplasty plus an individual extensor apparatus balancing procedure when assessed using the Kujala score. The likelihood of preventing the patella from subsequent post-operative redislocation/subluxation was, however, greater in patients who underwent trochleoplasty plus extensor balancing. LEVEL OF EVIDENCE: IV.

The Posterior Condylar Offset Ratio.

INTRODUCTION: Posterior Condylar Offset is an area of interest in knee arthroplasty research and clinical outcome. The aim of the study is to define a quantifiable Posterior Condylar Offset Ratio, a normal value for this ratio and to confirm its reproducibility on pre-operative radiographs. METHOD: We propose a new Posterior Condylar Offset Ratio which is defined as the maximal thickness of the posterior condyle projecting posteriorly to a straight line drawn as the extension of the posterior femoral shaft cortex, divided by the maximal thickness of the posterior condyle projecting posterior to a straight line drawn as the extension of the anterior femoral shaft cortex on a true lateral radiograph of the distal quarter of the femur. We have measured this on 100 true lateral radiographs (50 females, 50 males, and mean age 65 years). RESULTS: The mean ratio was 0.44 (SD 0.02) and was shown to have good reproducibility (intra-observer error 0.899 and inter-observer error 0.882. The ratio was also very consistent between male and female patients (0.44 (SD 0.02) for the males and 0.45 (SD 0.02) for the females). Adjusting the ratio for reported posterior condyle articular cartilage thickness increased the ratio to 0.47 (SD 0.02). CONCLUSION: We suggest our Posterior Condylar Offset Ratio is a useful tool to aid further research in this area of knee arthroplasty and propose a normal value of 0.44 on radiographs and 0.47 on post-operative knee arthroplasty radiographs.

Acute knee dislocation: an evidence based approach to the management of the multiligament injured knee.

Traumatic knee dislocations are uncommon yet serious injuries that historically have had variable prognosis. The evaluation and management of traumatic knee dislocations remains controversial. Appropriate early management has been shown to have a significant impact on long term functional outcome. A comprehensive review of the recent literature is presented alongside our current approach to management. The dislocated knee is an under diagnosed injury which relies on a high index of clinical suspicion on presentation of any knee injury. There is now a degree of consensus regarding need for surgery, timing of surgery, vascular investigations, surgical techniques and rehabilitation protocols. Vigilant monitoring for neurovascular complications, appropriate investigations and early involvement of surgeons with a specialist interest in knee ligament surgeries is the key to successful management of these difficult injuries.