The Banff Patellofemoral Instability Instrument 2.0 (BPII 2.0) is a patient-reported disease-specific quality of life (QOL) outcome measure used to assess patients with recurrent lateral patellofemoral instability (LPI) both pre- and post-operatively. The purpose of this study was to compare the BPII 2.0 to four other relevant patient reported outcome measures (PROMs): the Tampa Scale-11 for kinesiophobia (TSK-11), the pain catastrophizing scale (PCS), a general QOL (EQ-5D-5L), and a return to sport index (ACL-RSI). This concurrent validation sought to compare and correlate the BPII 2.0 with these other measures of physical, psychological, and emotional health. The psychological and emotional status of patients can impact recovery and rehabilitation, and therefore a disease-specific PROM may be unable to consistently identify patients who would benefit from interventions encompassing a holistic and person-focused approach in addition to disease-specific treatment. One hundred and ten patients with recurrent lateral patellofemoral instability (LPI) were assessed at a tertiary orthopaedic practice between January and October 2021. Patients were consented into the study and asked to complete five questionnaires: the BPII 2.0, TSK-11, PCS, EQ-5D-5L, and the ACL-RSI at their initial orthopaedic consultation. Descriptive demographic statistics were collected for all patients. A Pearson's r correlation coefficient was employed to examine the relationships between the five PROMs. These analyses were computed using SPSS 28.0 © (IBM Corporation, 2021). One hundred and ten patients with a mean age of 25.7 (SD = 9.8) completed the five PROMs. There were 29 males (26.3%) and 81 females (73.6%) involving 50% symptomatic left knees and 50% symptomatic right knees. The mean age of the first dislocation was 15.4 years (SD = 7.3; 1-6) and the mean BMI was 26.5 (SD = 7.3; range = 12.5-52.6) The results of the Pearson's r correlation coefficient demonstrated that the BPII 2.0 was statistically significantly related to all of the assessed PROM's (p. There was significant correlation evident between the BPII 2.0 and the four other PROMs assessed in this study. The BPII 2.0 does not explicitly measure kinesiophobia or pain catastrophizing, however, the significant statistical relationship of the TSK-11 and PCS to the BPII 2.0 suggests that this information is being captured and reflected. The preliminary results of this concurrent validation suggest that the pre-operative data may offer predictive validity. Future research will explore the ability of the BPII 2.0 to predict patient quality of life following surgery

Trochlear dysplasia is a developmental condition characterised by an abnormally flat or dome shaped trochlea and is an important contributing factor to patellofemoral instability and recurrent patellar dislocation. We prospectively studied a cohort of 54 consecutive patients (59 knees) with patellofemoral instability secondary to trochlear dysplasia, treated with a trochleoplasty by a single surgeon over a 5 year period. Patients were recruited from the senior author's specialist knee clinic and pre-operatively, multiple patient-centred scores were recorded. After the trochleoplasty, these were repeated along with a patient satisfaction questionnaire. Of the 54 patients and 59 knees operated, 39 of the patients (44 knees) were female and 15 (15 knees) male and 40 patients (42 knees) had follow-up of 12 months or more. Their mean age at surgery was 21 years and 6 months and mean length of follow up 2 years. One patient was unable to attend for follow up due to the development of a pelvic Ewings sarcoma. A statistically significant improvement in outcomes was demonstrated when the pre and post-operative scores were compared (mean scores of Oxford 26 to 19, WOMAC 23 to 17, IKDC 54 to 72, Kujala 62 to 76, Lysholm 57 to 78, p values <0.001 for all scores). 93% (50 patients) were satisfied with the outcome of their procedure. We conclude that in the short and medium term, the results of trochleoplasty are encouraging in this challenging group of patients

Chronic patello-femoral joint instability leads to recurrent subluxation and dislocation affecting knee function and preventing participation at sport. Traumatic dislocation of the patella results in rupture of the medial patello-femoral ligament (MPFL) in the majority of cases with a high incidence of chronic instability after a second dislocation. MPFL reconstruction can prevent recurrent dislocation and improve knee function. We report on our experience in MPFL reconstruction using hamstring tendons and its effect on the knee function in patients with chronic patello-femoral joint instability.

In this prospective study from 2005 to 2008, 68 patients (69 knees) with chronic patello-femoral instability were treated with MPFL reconstruction through a minimally invasive and arthroscopically assisted approach. In this procedure the semintendonosis with or without the gracilis tendon is routed from the pes anserinus to the most distal portion of the medial intramuscular septum before being secured to the superomedial border of the patella. All patients were evaluated pre-operatively and then post-operatively for a mean of 25 months (range 12-48 months). Knee function was assessed by the Tegner, Kujala and Lysholm scores.

There were 44 (65%) women and 24 (35%) men. Average age was 27 years. There were 2.7 mean pre-operative patellar dislocations (range 2-7). Mean follow-up was 19.6 months (range 12 to 56 months). IKDC score improved from 48.2 to 74.2, Kujala scores improved from 55.4 to 85.3. Lysholm scores improved from 52.4 to 77.3. Tegner activity scores improved from 2.5 to 5.4. There were overall 87% good to excellent results. No recurrent dislocations or wound related complications.

Medial patello-femoral reconstruction can provides excellent results in the treatment of patello-femoral joint instability with poor knee function.

Clinical management of patellofemoral (PF) instability is a challenge, particularly considering the wide range of contributing variables that must be taken into consideration when determining optimal treatment. An important outcome measure to consider in this patient population is disease-specific quality of life (QOL). The purpose of this study was to factor analyse and reduce the total number of items in the Banff Patellar Instability Instrument (BPII). Subsequent to the factor analysis, the new, item-reduced BPII 2.0 was tested for validity, reliability and responsiveness.

Disease-specific QOL was measured in patients with a confirmed diagnosis of PF instability (n = 223) at the initial consultation with the original BPII. Data from these BPII scores was used to employ a principal component analysis (PCA) to factor analyse and reduce the total number of items in the original BPII, to create the new BPII 2.0. The BPII 2.0 underwent content validation (Cronbach's Alpha, patient interviews and reading-level); construct validation (ANOVA comparing the initial consultation, 6, 12 and 24 month post-operative, Eta squared); convergent validation (Pearson r correlation to the original BPII); responsiveness testing (Eta squared, anchor-based distribution testing); and reliability testing (intra-class correlation coefficient (ICC) 2,k).

The original BPII was successfully reduced from 32 to 23 items. The new BPII 2.0 demonstrated excellent Cronbach's Alpha values: initial consult = 0.91; 6-months = 0.96; 12-months = 0.97; and 24-months post-operative = 0.76. Grade-level reading assessment for all items in the BPII 2.0 was below grade twelve. The ANOVA determined the BPII 2.0 was able to discriminate between the initial consultation, 6, 12 and 24 months post-operative assessments, with significant differences between each time-point (p < 0.05). Eta squared was 0.40, demonstrating a medium to large effect size. Convergent validity was established with the BPII 2.0 significantly correlated to the original BPII (initial consult = 0.82, 6-month = 0.90, 12-month = 0.90, and 24-month = 0.94). Anchor-based responsiveness was established with a significant correlation between the 7-point scale of patient-perceived improvement and 24-month post-operative BPII 2.0 scores. Strong reliability was established with an ICC (2,k) = .97.

The BPII has undergone a critical step in its psychometric and clinimetric evolution: structural validation. With the work completed in this study, the BPII and BPII 2.0 have completed assessment of seven of the nine Consensus-based Standards for the selection of health Measurement INstruments (COSMIN) properties including: 1) Internal consistency; 2) Reliability; 3) Standard error of measurement; 4) Content validation; 5) Structural validity; 6) Criterion validity; and, 7) Responsiveness testing. Completion of these assessments and the introduction of a structurally valid and shorter questionnaire, the BPII 2.0, provides a definitive level of credibility to this disease-specific outcome measure.

Introduction

The dysplastic trochlear is a developmental condition characterized by an abnormally flat or dome-shaped trochlea and it is recognized as a significant cause of patella instability. Surgical correction of the shape of the Trochlear Groove is frequently performed. The described methods in the literature involve open arthrotomy to normalize and maintain the trochlear morphology achieving normal alignment and tracking of the patella.

Classifying trochlear dysplasia (TD) is useful to determine the treatment options for patients suffering from patellofemoral instability (PFI). There is no consensus on which classification system is more reliable and reproducible for this purpose to guide clinicians in order to treat PFI. There are also concerns about validity of the Dejour classification (DJC), which is the most widely used classification for TD, having only a fair reliability score. The Oswestry-Bristol classification (OBC) is a recently proposed system of classification of TD and the authors report a fair-to-good interobserver agreement and good-to-excellent intra-observer agreement in the assessment of TD. The aim of this study was to compare the reliability and reproducibility of these two classifications. 6 assessors (4 consultants and 2 registrars) independently evaluated 100 magnetic resonance axial images of the patella-femoral joint for TD and classified them according to OBC and DJC. These assessments were again repeated by all raters after 4 weeks. The inter and intra-observer reliability scores were calculated using Cohen's kappa and Cronbach's alpha. Both classifications showed good to excellent interobserver reliability with high alpha scores. The OBC classification showed a substantial intra-observer agreement (mean kappa 0.628)[p<0.005] whereas the DJC showed a moderate agreement (mean kappa 0.572) [p<0.005]. There was no significant difference in the kappa values when comparing the assessments by consultants to those by registrars, in either classification systems. This large study from a non-founding institute shows both classification systems to be reliable for classifying TD based on magnetic resonance axial images of the patella-femoral joint, with the simple to use OBC having a higher intra-observer reliability score compared to the DJC

Recurrent patellar instability is a common problem and there are multiple demographic and pathoanatomic risk factors that predispose patients to dislocating their patella. The most common of these is trochlear dysplasia. In cases of severe trochlear dysplasia associated with patellar instability, a sulcus deepening trochleoplasty combined with a medial patellofemoral ligament reconstruction (MPFLR) may be indicated. Unaddressed trochlear pathology has been associated with failure and poor post-operative outcomes after stabilization. The purpose of this study is to report the clinical outcome of patients having undergone a trochleoplasty and MPFLR for recurrent lateral patellofemoral instability in the setting of high-grade trochlear dysplasia at a mean of 2 years follow-up. A prospectively collected database was used to identify 46 patients (14 bilateral) who underwent a combined primary MPFLR and trochleoplasty for recurrent patellar instability with high-grade trochlear dysplasia between August 2013 and July 2021. A single surgeon performed a thin flap trochleoplasty using a lateral para-patellar approach with lateral retinaculum lengthening in all 60 cases. A tibial tubercle osteotomy (TTO) was performed concomitantly in seven knees (11.7%) and the MPFLR was performed with a gracilis tendon autograft in 22%, an allograft tendon in 27% and a quadriceps tendon autograft in 57% of cases. Patients were assessed post-operatively at three weeks and three, six, 12 and 24 months. The primary outcome was the Banff Patellar Instability Instrument 2.0 (BPII 2.0) and secondary outcomes were incidence of recurrent instability, complications and reoperations. The mean age was 22.2 years (range, 13 to 45), 76.7% of patients were female, the mean BMI was 25.03 and the prevalence of a positive Beighton score (>4/9) was 40%. The mean follow-up was 24.3 (range, 6 to 67.7) months and only one patient was lost to follow-up before one year post-operatively. The BPII 2.0 improved significantly from a mean of 27.3 pre-operatively to 61.1 at six months (p < 0 .01) and further slight improvement to a mean of 62.1 at 12 months and 65.6 at 24 months post-operatively. Only one patient (1.6%) experienced a single event of subluxation without frank dislocation at nine months. There were three reoperations (5%): one for removal of the TTO screws and prominent chondral nail, one for second-look arthroscopy for persistent J-sign and one for mechanical symptoms associated with overgrowth of a lateral condyle cartilage repair with a bioscaffold. There were no other complications. In this patient cohort, combined MPFLR and trochleoplasty for recurrent patellar instability with severe trochlear dysplasia led to significant improvement of patient reported outcome scores and no recurrence of patellar dislocation at a mean of 2 years. Furthermore, in this series the procedure demonstrated a low rate (5%) of complications and reoperations

MPFL reconstruction has demonstrated a very high success rate with improved patella stability, physical function, and patient-reported outcomes. However technical error and a lack of consideration of anatomic risk factors have been shown to contribute to failure after MPFL reconstruction. Previous research has also reported a complication rate of 26% following surgery. The purposes of this study were to determine the re-dislocation rate, type and number of complications, and most common additional surgical procedures following MPFL reconstruction. Patients with symptomatic recurrent patellofemoral instability underwent an MPFL reconstruction (n = 268) and were assessed with a mean follow-up of 31.5 months (minimally 24-months). Concomitant procedures were performed in addition to the MPFL reconstruction in order to address significant anatomic or biomechanical characteristics. Failure of the patellofemoral stabilization procedure was defined as post-operative re-dislocation of the patella. Rates of complications and re-procedures were assessed for all patients. The re-dislocation rate following MPFL reconstruction was 5.6% (15/268). There were no patella fractures. A total of 49/268 patients (18.3%) returned to the operating room for additional procedures following surgery. The most common reason for additonal surgery was removal of symptomatic tibial tubercle osteotomy hardware in 24/268 patients (8.9%). A further 9.3% of patients underwent addtional surgery including revision MPFL reconstruction: with trochleoplasty 8/268 (3.0%), with tibial tubercule osteotomy 4/286 (1.5%) and with femoral derotation osteotomy 3/268 (1.1%); manipulation under anaesthesia for reduced knee range of motion 4/268 (1.5%); knee arthroscopy for pain 8/268 (3.0%); and cartilage restoration procedures 3/268 (1.1%). There was 1 case of wound debridement for surgical incision infection. MPFL reconstruction using an a la carte approach to surgical selection demonstrated a post-operative redislocation rate of 5.6%. The rate of complications following surgical stabilization was low, with the most common reason for additional surgery being removal of hardware

Patellofemoral instability is common injury and proximal soft tissue stabilisation via MPFL reconstruction or imbrication is the mainstay of treatment. The contribution of certain pathoanatomies to the failure of patellofemoral stabilisation is unknown. The purpose of this study was to analyse the failure rate of patellar stabilisation procedures in a large cohort as measured by re-dislocation of the patella. A secondary purpose was to identify the pathoantomical features that may have predisposed these patients to failure. Between May 2008 and March 2014, 207 MPFL reconstructions and 70 MPFL imbrications were performed by a single surgeon. Post-operative assessment included clinical examination to assess the integrity of the MPFL graft, plain radiographs and the Banff Patellofemoral Instability Instrument (BPII), a disease-specific outcome measure. Failures were identified and risk factors including trochlear dysplasia, patella alta, generalised ligamentous laxity (GLL), femoral tunnel position and rotational abnormalities were evaluated as contributing factors. There were 48 male and 178 female patients. The mean duration of follow-up was 24.1 months (SD 9.4, range 12–74). The average age at time of surgery was 24.81 years (SD 8.87, range 50.35–8.99). The average BMI was 23.75 (SD 3.62, range 36.70–14.90). There were 10 failures in the MPFL reconstruction group (4.8%), 1 male and 9 females. Femoral tunnel position was assessed in relation to Schottle's point as good or excellent in all 10 cases. In terms of pathoanotomy, 8/10 failures had high-grade trochlear dysplasia, 1/10 had patella alta, 6/10 had a Beighton score of >/= 4, and 3/10 had clinically significant rotational abnormalities of the lower extremity. The primary cause attributed to the 10 failure cases was trauma in two, trochlear dysplasia in three, rotational abnormalities in one, combined femoral anteversion and GLL in two, and combined trochlear dysplasia and GLL in two. There were 13 failures in the MPFL imbrication group (18.6%), 2 males and 11 females. Among these failures, 4/13 had high-grade trochlear dysplasia, 3/13 had patella alta, 10/13 had a Beighton score of >/= 4, and one had clinically significant rotational abnormalities of the lower extremity. The primary pathology that was considered to contribute to the imbrication failure cases was trochlear dysplasia in four, generalised ligamentous laxity in six, rotational abnormalities in one, patella alta with trochlear dysplasia in one, and generalised ligamentous laxity with trochlear dysplasia in one. Prior to surgical failure the mean BPII score for the failure group was 71.5/100, compared with 74.6/100 for the remainder of the cohort. MPFL reconstruction is highly successful surgical procedure for stabilising the unstable patella with a failure rate of only 4.8%. Higher failure rates are seen in patients undergoing imbrication of the MPFL compared to a reconstruction. Pathoanatomies that contribute to failure vary between patients with the most common being trochlear dysplasia and generalised ligamentous laxity

Purpose of Study:. Various techniques have been described and are still used for treating recurrent dislocation of the patella when conservative measures fail. Among them are distal, proximal and combined realignment techniques and lateral releases. Since being shown proof of the biomechanical importance of the medial patellofemoral ligament (MPFL) in patellofemoral instability, the reconstruction of the MPFL has gained in popularity. The objective of this paper is to present a case series with preliminary clinical results using the gracilis tendon to reconstruct the MPFL. Method:. Between 01/07 and 03/11 23 knees in 21 patients underwent reconstruction of the MPFL.4 of these patients had had previous surgery. Preoperatively the Caton Deschamps ratio using plain x-rays was worked out and the TT/TG distance was measured using CT scanning. Using these measurements as a guideline, 7 cases underwent a tibial tubercle transfer as an additional procedure. In 6 of the cases an additional cartilage procedure was required. The technique was simplified using intra-operative x-rays to achieve anatomical tunnel placement. Results:. The Tegner Activity Score was used to evaluate the patients preoperatively and at a minimum of 6 months postoperatively. The scores improved on average from 3,6 to 7,4. One patient had an extensor lag of 10 degrees at 3 months. This had normalised by 6 months. One patient had recurrence of her instability and required a revision MPFL reconstruction using an allograft. One patient had recurrent episodes of patella subluxation but no overt dislocation. Conclusion:. This case series gave good functional results using the Tegner Activity score. The procedure of MPFL reconstruction was effective in stabilising the patellae and in improving the symptoms of patellofemoral instability

Medial patellofemoral ligament (MPFL) reconstruction is an effective procedure to address patellofemoral instability, however there remains no clear consensus on the optimum technique. Variations in patella tunnel and the use of patella fixation devices are reported in the literature, as are the associated complications of patella fracture and hardware irritation. We present the early results using a two tunnel, Endobutton free technique. 24 MPFL reconstructions (14 female, 10 male) were performed by a single surgeon, using two 3.5mm medial patellar tunnels exiting anteriorly and a looped, extra-synovial hamstring autograft. Femoral fixation was achieved using an non-absorbable interference screw. Mean age was 25.5 years, with a mean follow-up of 21.7 months. Mean Kujala scores were 60.8 preoperatively and 87.9 postoperatively (p<0.0001). No patient experienced further dislocation or patella fracture post-operatively. One patient required interference screw removal. The surgical technique presented has outcomes comparable with the literature. It requires a shorter tendon graft, and removes the need for a patellar fixation device, reducing potential irritation and cost

Introduction. Malrotation of the tibial component would lead to various complications after total knee arthroplasty (TKA) such as improper joint kinematics, patellofemoral instability, or excessive wear of polyethylene. However, despite reports of internal rotation of the tibial component being associated with more severe pain or stiffness than external rotation, the biomechanical reasons remain largely unknown. In this study, we used a musculoskeletal computer model to simulate a squat (0°–130°–0° flexion) and analyzed the effects of malrotated tibial component on lateral and medial collateral ligament (LCL and MCL) tensions, tibiofemoral and patellofemoral contact stresses, during the weight-bearing deep knee flexion. Materials and Methods. A musculoskeletal model, replicating the dynamic quadriceps-driven weight-bearing knee flexion in previous cadaver studies, was simulated with a posterior cruciate-retaining TKA. The model included tibiofemoral and patellofemoral contact, passive soft tissue and active muscle elements. The soft tissues were modeled as nonlinear springs using previously reported stiffness parameters, and the bony attachments were also scaled to some cadaver reports. The neutral rotational alignment of the femoral and tibial components was aligned according to the femoral epicondylar axis and the tibial anteroposterior axis, respectively. Knee kinematics and ligament tensions were computed during a squat for malrotated conditions of the tibial component. The tibial rotational alignments were changed from 15° external rotation to 15° internal rotation in 5° increments. The MCL and LCL tensions, the tibiofemoral and patellofemoral contact stresses were compared among the knees with different rotational alignment. Results. For the MCL, the neutral rotated tibial components caused a maximum tension of 67.3 N. However, the 15° internally rotated tibial components increased tensions to 285.2N as a maximum tension [Fig.1]. By contrast, with external rotation of the tibial component, the MCL tensions increased only a small amount. The LCL tension also increased but up to less than half of the MCL value [Fig.2]. The tibiofemoral and patellofemoral contact stresses increased because of a decreased contact area [Fig.3]. Discussion and Conclusion: In this computer simulation, excessive internal rotation in the tibial component increased MCL tensions and patellofemoral and tibiofemoral contact stresses. The current study suggests that increased MCL tensions and patellofemoral and tibiofemoral contact stresses caused by a malrotated tibial component could be one cause of patient complaints and polyethylene problems after TKA

Total knee arthroplasty (TKA) has produced excellent results, but many surgeons are hesitant to perform TKA in younger patients with isolated patellofemoral arthritis. In properly selected patients, patellofemoral arthroplasty (PFA) is an effective procedure with good long-term results. Contemporary PFA prostheses have eliminated many of the patellar maltracking problems associated with older designs, and short-term results, as described here, are encouraging. Long-term outcome and prospective trials comparing TKA to PFA are needed. Incidence. Isolated patellofemoral arthritis occurs in as many as 11% of men and 24% of women older than age 55 years with symptomatic osteoarthritis (OA) of the knee; Isolated patellofemoral arthritis found in 9.2% of patients older than age 40 years; 7% to 19% of patients experience residual anterior knee pain when TKA is done for isolated patellofemoral arthritis. Imaging. Weight bearing AP radiographs as supine radiographs can underestimate the extent of tibiofemoral arthritis; Midflexion posteroanterior radiographs to rule out posterior condylar wear; Lateral radiographs to identify the presence or absence of patella alta or baja; Axial radiographs identify the presence of trochlear dysplasia, patellar tilt or subluxation, and extent of patellofemoral arthritis; Magnetic resonance imaging and arthroscopic photographs should be reviewed if available. Indications. Osteoarthritis limited to the patellofemoral joint; Symptoms affecting daily activity referable to patellofemoral joint degeneration unresponsive to lengthy nonoperative treatment; Posttraumatic osteoarthritis; Extensive Grade-III chondrosis; Failed extensor unloading surgical procedure; Patellofemoral malalignment/dysplasia-induced degeneration. Contraindications. No attempt at nonoperative care or to rule out other sources of pain; Arthritis of greater than Grade 1 involving tibiofemoral articulation; Systemic inflammatory arthropathy; Osteoarthritis/chondrosis of the patellofemoral joint of Grade 3 or less; Patella baja; Uncorrected patellofemoral instability or malalignment; Uncorrected tibiofemoral mechanical malalignment; Active infection; Evidence of chronic regional pain syndrome or evidence of psychogenic pain; Fixed loss of knee range of motion, minimum 10–110 degrees ROM. Results. Majority of failures related to patellar instability from uncorrected patellar malalignment, soft-tissue imbalance, or component malposition; With improved implant designs tibiofemoral arthritis has become the primary source of failure; Failure from component subsidence or loosening occurring in <1% of knees. Our Series. Retrospective review 34 patients, 40 knees average 30 month follow-up using Natural Knee II Patello-femoral Joint System (Zimmer, Warsaw, IN); Average age 61, ranging from 34–84 years of age; Average subset KOOS scores were 93 for pain, 94 for symptoms, 94 for ADL's, 70 for sports and recreation, 82 for quality of life; Average pre-operative Tegner score 2.6, increasing to 4.7 post-operatively; 38/40 survival over 30 months with the two failures undergoing revision for traumatic injuries; No revisions to TKA; At most recent follow-up no progression of OA to involve tibiofemoral compartments; No evidence of component loosening