Patellofemoral osteoarthritis after Insall’s proximal realignment for recurrent patellar dislocation

Purpose

The aim of the present study was to retrospectively investigate the development of patellofemoral osteoarthritis after the historical Insall’s proximal realignment for patellar stabilisation in patients with recurrent patellar dislocation. Furthermore, risk factors for recurrent patellar dislocation and for patellofemoral osteoarthritis development were evaluated.

Methods

Forty-two patients underwent patellofemoral stabilising surgery by the historic Insall’s proximal realignment; they were evaluated with a mean follow-up period of 52 months. Plain radiography was used to document osteoarthritic changes by using the Iwano classification. MRIs obtained at the latest follow-up were evaluated for patellofemoral cartilage lesions. Univariate and multivariate logistic regression analyses were performed to evaluate the influence of trochlear dysplasia, tibial tubercle–trochlear groove distance and patellar height on redislocation. Pearson’s χ ² and the Spearman’s correlation tests were used to assess a possible correlation between trochlear dysplasia and patellar dislocation, as well as between instability and development of patellofemoral osteoarthritis.

Results

At the latest follow-up, plain radiographs showed a significant increase in patellofemoral osteoarthritis (grades II–IV according to the Iwano classification) in 18 patients (43 %) compared with 4 patients (10 %) at the time of surgery (P = 0.001). Patellofemoral cartilage lesions (grades II–IV) were detected in 18 patients (43 %) on MRI. Nine patients (21 %) had at least one incidence of redislocation at follow-up. Estimated redislocation-associated risk factors could not be determined. Trochlear dysplasia had a significant impact on patellofemoral osteoarthritis development (P = 0.001), whereas recurrent patellar instability had none (n.s.).

Conclusion

Insall’s proximal realignment technique leads to a significant progression of patellofemoral osteoarthritis. No risk factors for redislocation could be found; however, the presence of trochlear dysplasia did correlate with patellofemoral osteoarthritis.

Level of evidence

IV.     

A matched-pair comparison of inlay and onlay trochlear designs for patellofemoral arthroplasty: no differences in clinical outcome but less progression of osteoarthritis with inlay designs

Purpose

To compare clinical and radiographic results after isolated patellofemoral arthroplasty (PFA) using either a second-generation inlay or onlay trochlear design. The hypothesis was that an inlay design will produce better clinical results and less progression of tibiofemoral osteoarthritis (OA) compared to an onlay design.

Methods

Fifteen consecutive patients undergoing isolated PFA with an onlay design trochlear component (Journey? PFJ, Smith & Nephew) were matched with 15 patients after isolated PFA with an inlay design trochlear component (HemiCAP^® Wave, Arthrosurface). Matching criteria were age, gender, body mass index, and follow-up period. An independent observer evaluated patients prospectively, whereas data were compared retrospectively. Clinical outcome was assessed using WOMAC, Lysholm score, and pain VAS. Kellgren–Lawrence grading was used to assess progression of tibiofemoral OA.

Results

Conversion to total knee arthroplasty was necessary in one patient within each group, leaving 14 patients per group for final evaluation. The mean follow-up was 26 months in the inlay group and 25 months in the onlay group (n.s.). Both groups displayed significant improvements of all clinical scores (p < 0.05). No significant differences were found between the two groups with regard to the clinical outcome and reoperation rate. No significant progression of tibiofemoral OA was observed in the inlay group, whereas 53 % of the onlay group showed progression of medial and/or lateral tibiofemoral OA (p = 0.009).

Conclusion

Isolated PFA using either a second-generation inlay or onlay trochlear component significantly improves functional outcome scores and pain. The theoretical advantages of an inlay design did not result in better clinical outcome scores; however, progression of tibiofemoral OA was significantly less common in patients with an inlay trochlear component. This implant design may therefore improve long-term results and survival rates after isolated PFA.

Level of evidence

III.

     

Association of trochlear dysplasia with degenerative abnormalities in the knee: data from the Osteoarthritis Initiative

Objective

To evaluate trochlear morphology as a potential risk factor for patellofemoral osteoarthritis, determined by morphological and quantitative measurements of cartilage degeneration using 3-T magnetic resonance imaging (MRI) of the knee.

Materials and methods

MRI of the right knees of 304 randomly selected subjects, aged 45–60 years, from the Osteoarthritis Initiative (OAI) progression cohort were screened for trochlear dysplasia, defined by an abnormal trochlear depth. Out of 304 subjects, n?=?85 demonstrated a shallow trochlea (depth ≤3 mm; 28 %). In these, and also in a random sample of controls with normal trochlear depth (n?=?50), the facet ratio and the sulcus angle were calculated and knee structural abnormalities were assessed by using a modified Whole Organ MR Imaging Score (WORMS). Cartilage segmentation was performed and T₂ relaxation times and patellar cartilage volume were determined. ANOVA and multivariate regression models were used for statistical analysis of the association of MRI structural measures and trochlear morphology.

Results

Knees with a shallow trochlea showed higher patellofemoral degeneration (WORMS mean ± standard deviation, 11.2?±?0.5 versus 5.7?±?0.6; multivariate regression, P?<?0.001) and lower patellar cartilage volume than controls (900?±?664 mm³ versus 1,671?±?671 mm³; P?<?0.001). Knees with an abnormal medial-to-lateral facet ratio (<0.4) showed increased patellofemoral WORMS scores (12.3?±?0.9 versus 8.3?±?0.5; P?<?0.001). Knees with an abnormal sulcus angle (>170°) also showed increased WORMS scores (12.2?±?1.1 versus 8.6?±?0.6; P?=?0.003). T₂ values at the patella were significantly lower in the dysplasia group with a shallow trochlea. However, significance was lost after adjustment for cartilage volume (P?=?0.673).

Conclusion

Trochlear dysplasia, defined by a shallow trochlea, was associated with higher WORMS scores and lower cartilage volume, indicating more advanced osteoarthritis at the patellofemoral joint.     

Combined trochleoplasty and MPFL reconstruction for treatment of chronic patellofemoral instability: a prospective minimum 2-year follow-up study

Purpose

Excessive trochlear dysplasia may be responsible for recurrent patellofemoral instability (PFI) due to a missing bony guidance for the patella in early flexion. Thus, an isolated medial patellofemoral ligament reconstruction (MPFLR) can be insufficient, since it mainly addresses instability close to extension and additionally can increase patellofemoral pressure leading to pain in flat or convex trochlear dysplasia. Therefore, in combination with a trochleoplasty, an anatomical trochlear groove is created, resulting in patellofemoral stability also in flexion, while patellofemoral pressure is normalized. In this prospective study, we evaluated the outcome of open trochleoplasty in combination with MPFLR with a minimum follow-up of 2 years for treatment of excessive PFI.

Methods

In between 2007 and 2009, 18 knees of 17 consecutive patients (mean age of 22.2 ± 4.9 years) with trochlear dysplasia type B, C or D according to Dejour et al. and positive apprehension from 0 to 60° of flexion were included. Tegner, Kujala and IKDC scores, apprehension and pain, trochlear dysplasia, sulcus angle, tibial tuberosity trochlear groove, patellar tilt and shift, Caton–Deschamps index as well as patellofemoral arthrosis according to the classification of Iwano et al. were assessed pre- and postoperatively.

Results

At a mean of 30.5 ± 5.9 months, all but one patient were subjectively satisfied with the outcome of the procedure, all showing absence of positive apprehension or redislocation. Significant (p < 0.001) reduction in pain (5.6 to 2.5 ± 2.8 points, VAS) and increase in Tegner (2, range 0–4 points to 6, range 3–8 points), Kujala (51.1 to 87.9 ± 20.0 points) and IKDC (49.5 to 80.2 ± 21.0 %) scores could be achieved. Radiologically significant (p < 0.02) improvement of patellofemoral positional parameters leading to more normal anatomy was recorded, while short-term arthrosis was absent.

Conclusions

Combined treatment for trochleoplasty with MPFLR serves as a successful therapy for chronic PFI. This combinatory treatment concept is a reliable option not only as salvage therapy but also as primary procedure regarding treatment for excessive PFI.

Level of evidence

Prospective case series, Level IV.     

The prevalence of patellofemoral osteoarthritis 12 years after anterior cruciate ligament reconstruction

Purpose

To investigate the prevalence of patellofemoral osteoarthritis (OA) and to explore the association between radiographic patellofemoral OA and symptoms and function 12 years after anterior cruciate ligament (ACL) reconstruction.

Methods

The study participants (n = 221) were consecutively included at the time of an ACL reconstruction in the period from 1990 to 1997. Knee laxity (KT-1000), isokinetic quadriceps strength, triple jump, stair hop, and the Cincinnati knee score were measured 6 months, 1 year, 2 years, and 12 years after surgery. At the 12-year follow-up, visual analogue scale for pain, the Knee injury and Osteoarthritis Outcome Score, the Tegner activity scale, and radiographic examination (Kellgren and Lawrence score) were added. To analyse the association between patellofemoral OA, symptoms, and function, binary regression analyses presenting odds ratios and 95 % confidence intervals were used. The analyses were adjusted for age, gender, and body mass index.

Results

One hundred and eighty-one of the 221 subjects (82 %), including 76 females (42 %) and 105 males (58 %), were evaluated at the 12.3 ± 1.2-year follow-up. Mean age at the follow-up was 39.1 ± 8.7 years. Additional meniscal or chondral injuries at the time of reconstruction or during the follow-up period were detected in 116 subjects (64 %). Radiographic patellofemoral OA was found in 48 subjects (26 %), including 3 subjects with isolated patellofemoral OA (1.5 %). Those with patellofemoral OA were older, had more tibiofemoral OA, and had significantly more symptoms and impaired function compared with those without patellofemoral OA.

Conclusions

Patellofemoral OA was found in 26 % 12 years after ACL reconstruction. Patellofemoral OA was associated with increased age, tibiofemoral OA, increased symptoms, and reduced function. It is of clinical importance to include functional and radiographic assessment of the patellofemoral joint in the examination of long-term consequences following an ACL reconstruction.

Level of evidence

II.     

The relationship between patellofemoral and tibiofemoral morphology and gait biomechanics following arthroscopic partial medial meniscectomy

Purpose

To examine the relationship between tibiofemoral and patellofemoral joint articular cartilage and subchondral bone in the medial and gait biomechanics following partial medial meniscectomy.

Methods

For this cross-sectional study, 122 patients aged 30–55 years, without evidence of knee osteoarthritis at arthroscopic partial medial meniscectomy, underwent gait analysis and MRI on the operated knee once for each sub-cohort of 3 months, 2 years, or 4 years post-surgery. Cartilage volume, cartilage defects, and bone size were assessed from the MRI using validated methods. The 1st peak in the knee adduction moment, knee adduction moment impulse, 1st peak in the knee flexion moment, knee extension range of motion, and the heel strike transient from the vertical ground reaction force trace were identified from the gait data.

Results

Increased knee stance phase range of motion was associated with decreased patella cartilage volume (B = ?17.9 (95 % CI ?35.4, ?0.4) p = 0.045) while knee adduction moment impulse was associated with increased medial tibial plateau area (B = 7.7 (95 % CI 0.9, 13.3) p = 0.025). A number of other variables approached significance.

Conclusions

Knee joint biomechanics exhibited by persons who had undergone arthroscopic partial meniscectomy gait may go some way to explaining the morphological degeneration observed at the patellofemoral and tibiofemoral compartments of the knee as patients progress from surgery.

Level of evidence

III.     

Evidence of trochlear dysplasia in patellofemoral arthroplasty designs

Purpose

The design of the trochlear compartment is crucial in patellofemoral arthroplasty (PFA), because 78 % of patients with isolated patellofemoral arthritis present concomitant trochlear dysplasia with patellar maltracking and therefore remain predisposed to post-operative patellar subluxation and dislocation. The study investigated whether current PFA implants are designed with anatomic trochlear parameters such as the sulcus angle, lateral facet height and groove orientation.

Methods

Five trochlear components of commercially available PFA implants were scanned, and the generated three-dimensional surfaces were measured using engineering design software. The mediolateral trochlear profiles were plotted at various flexion angles (0°, 15°, 30° and 45°) to deduce the following variables: sulcus angle, height of lateral facet and trochlear groove orientation.

Results

Four specimens had sulcus angle >144° in the 45° of flexion, and all five specimens had sulcus angle >143° in 30° of flexion. Three specimens had a facet <5 mm high through the entire range of early flexion (0°–30°), and two specimens had a facet <5 mm high beyond early flexion (30°–45°). The trochlear groove was oriented laterally in all specimens (range 1.6°–13.5°).

Conclusion

Current PFA trochlear components are not always designed with anatomic parameters, and some models exhibit characteristics of trochlear dysplasia. Surgeons are therefore advised to implant components with a deep sulcus, particularly in patients with history of patellofemoral disorders, and to adapt the surgical technique and extensor mechanism if the component implanted has a shallow sulcus, to ensure normal patellar tracking.

Level of evidence

III.     

Patellofemoral arthroplasty influences tibiofemoral kinematics: the effect of patellar thickness

Purpose

Although controversy still remains, isolated patellofemoral arthroplasty recently gained in popularity as a treatment option for patellofemoral osteoarthritis. It has compared to total knee arthroplasty the advantage of preserving the tibiofemoral articulation, which in theory would allow the preservation of natural tibiofemoral kinematics. Today, however, no data exist to support this assumption. This study was therefore performed in order to investigate the effect of isolated patellofemoral arthroplasty on the native three-dimensional tibiofemoral kinematic behaviour and whether a change in patellar thickness would have an influence.

Methods

Six fresh-frozen cadavers were fixed on a custom-made mechanical knee rig. Full 3D kinematics was analysed during passive flexion–extension cycles, open chain extension, with and without mechanical resistance, as well as deep knee squats, using infrared motion capture cameras and retroflective markers. Measurements were taken for the native knee and after prosthetic trochlear resurfacing with and without patellar resurfacing in three different patellar thicknesses.

Results

Compared to the natural knee, patellofemoral arthroplasty resulted in significant changes in tibiofemoral kinematics, which were most pronounced in the most loaded motor tasks. Increased internal tibial rotation was noted in the mid- and high flexion ranges, reaching at 120° of flexion a mean difference of 4.5° ± 4.3° (p < 0.0001) during squat motion, over the whole flexion range during open chain motion and in deeper flexion beyond 50° (mean at 70°, 1.9° ± 3.7°) during resisted open chain. During squats, also, a more posterior translation of the lateral femoral condyle was observed. The effect was accentuated in case of patella overstuffing, whereas kinematics was closer to normal with patellar thinning.

Conclusion

Isolated patellofemoral arthroplasty alters natural tibiofemoral kinematics, and the effects become more pronounced in case of increased patellar thickness. Therefore, it might be recommended to aim for a slight over-resection of patellar bone if sufficient bone stock is available.     

Strong correlation between the morphology of the proximal femur and the geometry of the distal femoral trochlea

Purpose

Previous investigations suggested that the geometry of the proximal femur may be related to osteoarthritis of the tibiofemoral joint and various patellofemoral joint conditions. This study aims to investigate the correlation between proximal and distal femoral geometry. Such a correlation could aid our understanding of patient complications after total knee arthroplasty (TKA) and be of benefit for further development of kinematic approaches in TKA.

Methods

CT scans of 60 subjects (30 males, 30 females) were used to identify anatomical landmarks to calculate anatomical parameters of the femur, including the femoral neck anteversion angle, neck–shaft angle (NSA), mediolateral offset (ML-offset), condylar twist angle (CTA), trochlear sulcus angle (TSA) and medial/lateral trochlear inclination angles (MTIA/LTIA). Correlation analyses were carried out to assess the relationship between these parameters, and the effect of gender was investigated.

Results

The CTA, TSA and LTIA showed no correlation with any proximal parameter. The MTIA was correlated with all three proximal parameters, mostly with the NSA and ML-offset. Per 5° increase in NSA, the MTIA was 2.1° lower (p < 0.01), and for every 5 mm increase in ML-offset, there was a 2.6° increase in MTIA (p < 0.01). These results were strongest and statistically significant in females and not in males and were independent of length and weight.

Conclusions

Proximal femoral geometry is distinctively linked with trochlear morphology. In order to improve knowledge on the physiological kinematics of the knee joint and to improve the concept of kinematic knee replacement, the proximal femur seems to be a factor of clinical importance.

Level of evidence

III.     

Partial lateral facetectomy plus Insall’s procedure for the treatment of isolated patellofemoral osteoarthritis: survival analysis

Purpose

The purpose of this study was to report the survival analysis of partial lateral facetectomy and Insall’s procedure in patients with isolated patellofemoral osteoarthritis, and to assess the risk and protective factors for failure of this procedure.

Methods

From 1992 to 2004, all subjects with isolated patellofemoral osteoarthritis who met the inclusion criteria and underwent this procedure were enrolled. Risk and protective factors for failure (failure considered as the need for total knee arthroplasty) were assessed by comparing obtained baseline data between failed and non-failed cases. Eighty-seven cases (mean (SD) age 61.8 (7.7) years, mean (SD) follow-up 9.6 (3.2) years) were included.

Results

Twenty-three failed cases were found. Mean (SD) survival time was 13.6 (0.5) years. At 13 years (last failure case), the cumulative survival was 59.3 %. Baseline medial tibiofemoral pain, genu flexum, and worst grade of tibiofemoral osteoarthritis were significant risk factors for failure (p < 0.0001, p = 0.02, p < 0.0001, respectively). In contrast, higher anatomical (p = 0.02) and total (p = 0.03) knee society score (KSS) scores, absence of knee effusion (p = 0.03), higher value of the Caton–Deschamps index (p = 0.03), and lateral position of the patella (p = 0.01) were all protective factors against failure.

Conclusion

The treatment for isolated patellofemoral osteoarthritis through partial lateral facetectomy and Insall’s procedure demonstrated good long-term survival. The presence of preoperative medial tibiofemoral pain, genu flexum, and incipient tibiofemoral osteoarthritis increased the risk of failure of this procedure. In contrast, higher anatomical and total KSS scores, absence of knee effusion, higher value of the Caton–Deschamps index, and lateral position of the patella were found to protect against failure.

Level of evidence

Prospective case series, Level IV.     

Association between varus alignment and post-traumatic osteoarthritis after anterior cruciate ligament injury

Purpose

To investigate the association between varus alignment and post-traumatic osteoarthritis (OA) after an anterior cruciate ligament (ACL) injury.

Methods

One hundred subjects with an acute complete ACL tear were followed for 15 years. Anterior–posterior radiographs of the tibiofemoral joint were obtained with a knee flexion of 20°, and the patellofemoral joint was examined with skyline view at 50° knee flexion. Joint space narrowing and osteophytes were graded in the tibiofemoral and patellofemoral joints in the injured (ACL) and uninjured knee according to the radiographic atlas of the Osteoarthritis Research Society International. The alignment of the uninjured, contralateral knee was measured at follow-up, using full-limb radiographs of leg with the knee in full extension. Alignment was expressed as the hip-knee-ankle (HKA) angle. Alignment was defined as valgus (HKA ≤178°), neutral (179°–181°) or varus (≥182°).

Results

Data from 68 subjects were included in the analysis. Varus alignment of the uninjured knee at follow-up appeared to be associated with OA of the injured knee 15 years after an ACL injury (odds ratio (95 % confidence interval) 3.9 (1.0–15.8, p = 0.052)).

Conclusions

Varus alignment of the uninjured knee at follow-up may be associated with OA of the injured knee 15 years after an ACL injury.

Level of evidence

II.     

Arthroscopic evaluation of trochlear dysplasia as an aid in decision making for the treatment of patellofemoral instability

Purpose

Trochlear dysplasia is an important aetiological factor for the development of patellofemoral instability (PFI). The aim of the study was to identify the arthroscopic morphology of trochlear dysplasia that can be helpful when planning operative treatment for PFI.

Methods

Magnetic resonance imaging (MRI) scans and strict lateral radiographs of 46 patients treated for PFI were assigned according to Dejour and matched with arthroscopic views from the lateral superior arthroscopic portal. On arthroscopy, signs of trochlear dysplasia were identified and classified into two types. Intra- and inter-observer agreements of the arthroscopic evaluation were assessed.

Results

Arthroscopically, 2 major types of trochlear dysplasia could be distinguished. Type I shows a flat trochlear groove with an elevated trochlear floor in relation to the anterior femoral cortex. In type II, the proximal trochlea was convex with a lateral trochlear bump. Arthroscopic evaluation was not consistent with the Dejour’s radiographic and axial MRI classification. Arthroscopic grading showed excellent intra- and inter-observer agreements (81–92 %).

Conclusion

Arthroscopic evaluation can give additional information about the severity of trochlear dysplasia. This additional information can be used as an aid in decision making for the treatment of PFI.

Level of evidence

II.     

Influence of tibial slope asymmetry on femoral rotation in patients with lateral patellar instability

Purpose

The geometry of the tibial plateau and its influence on the biomechanics of the tibiofemoral joint has gained increased significance. However, no quantitative data are available regarding the inclination of the medial and lateral tibial slope in patients with patellar instability. It was therefore the purpose of this study to evaluate tibial slope characteristics in patients with patellar dislocations and to assess the biomechanical effect of medial-to-lateral tibial slope asymmetry on lateral patellar instability.

Methods

Medial and lateral tibial slope was measured on knee magnetic resonance images in 107 patients and in 83 controls. The medial-to-lateral tibial slope asymmetry was assessed as the intra-individual difference between the medial and lateral tibial plateau inclination considering severity of trochlear dysplasia. The effect of tibial slope asymmetry on femoral rotation was calculated by means of radian measure.

Results

Severity of trochlear dysplasia was significantly associated with an asymmetric inclination of the tibial plateau. Whereas the medial tibial slope showed identical values between controls and study patients (n.s.), lateral tibial plateau inclination becomes flatter with increasing severity of trochlear dysplasia (p < 0.01). Consequently, the intra-individual tibial slope asymmetry increased steadily (p < 0.01) and increased internal femoral rotation in 20° and 90° of knee flexion angles in patients with severe trochlear dysplasia (p < 0.01). In addition, the extreme values of internal femoral rotation were more pronounced in patients with patellar instability, whereas the extreme values of external femoral rotation were more pronounced in control subjects (p = 0.024).

Conclusion

Data of this study indicate an association between tibial plateau configuration and internal femoral rotation in patients with lateral patellar instability and underlying trochlear dysplasia. Thereby, medial-to-lateral tibial slope asymmetry increased internal femoral rotation during knee flexion and therefore might aggravate the effect of femoral antetorsion in patients with patellar instability.

Level of evidence

III.     

Treatment of isolated patellofemoral osteoarthritis with lateral facetectomy plus Insall’s realignment procedure: long-term follow-up

Purpose

To assess the long-term results of lateral facetectomy plus Insall’s realignment procedure to treat isolated patellofemoral osteoarthritis.

Methods

All consecutive patients undergoing this procedure with a follow-up between 10 and 14 years were included in this study. Subjects were excluded if they had previous patellar dislocation, patellar fracture, tibiofemoral osteoarthritis (except mild cases) or follow-up <10 or >14 years. Failure cases (need for total knee arthroplasty) of this surgical procedure before 10 years of follow-up were considered in the overall failure rate. Clinical, functional and radiographic outcomes were obtained at baseline and compared to postoperative values.

Results

Forty-three patients (mean (SD) age 59.7 (8.1) years) had a follow-up between 10 and 14 years and were finally included in this study. The failure rate in the whole series and included patients was 26.4 and 16.3 %, respectively, for a mean (SD) follow-up of 9.2 (3.2) years and 11.7 (1.4) years, respectively. Patellofemoral pain (p < 0.0001), need for NSAIDs (p < 0.0001), longitudinal (p < 0.0001) and transversal (p < 0.0001) patellar glide tests, Zholen’s sign (p = 0.0007) and knee effusion (p = 0.02) significantly improved in the follow-up. Postoperative Knee Society Score (KSS) anatomical (p < 0.0001), functional (p < 0.0001) and total (p < 0.0001) scores and Kujala’s score (p = 0.001) were significantly higher compared to preoperative values. The patellar tilt (p = 0.001) and shift (p = 0.04) significantly improved postoperatively, whereas the patellofemoral osteoarthritis was not modified (n.s.) with respect to preoperative assessment.

Conclusions

The lateral facetectomy plus Insall’s realignment procedure was a successful treatment for isolated patellofemoral osteoarthritis from a clinical, functional and radiographic point of view in the long-term follow-up.

Level of evidence

Prospective case series, Level IV.     

Measurement of tibial tuberosity–trochlear groove distance: evaluation of inter- and intraobserver correlation dependent on the severity of trochlear dysplasia

Purpose

Excessive tibial tuberosity–trochlear groove distance (TT–TG) is considered as one of the major risk factors in patellofemoral instability (PFI). TT–TG characterises the lateralisation of the tibial tuberosity and the medialisation of the trochlear groove in the case of trochlear dysplasia. The aim of this study was to assess the inter- and intraobserver reliability of the measurement of TT–TG dependent on the grade of trochlear dysplasia.

Methods

Magnetic resonance imaging (MRI) scans of 99 consecutive knee joints were analysed retrospectively. Hereof, 61 knee joints presented with a history of PFI and 38 had no symptoms of PFI. After synopsis of the axial MRI scans with true lateral radiographs of the knee, the 61 knees presenting with PFI were assessed in terms of trochlear dysplasia. The knees were distributed according to the four-type classification system described by Dejour.

Results

Regarding interobserver correlation for the measurements of TT–TG in trochlear dysplasia, we found r = 0.89 (type A), r = 0.90 (type B), r = 0.74 (type C) and 0.62 (type D) for Pearson’s correlation coefficient. Regarding intraobserver correlation, we calculated r = 0.89 (type A), r = 0.91 (type B), r = 0.77 (type C) and r = 0.71 (type D), respectively. Pearson’s correlation coefficient for the measurement of TT–TG in normal knees resulted in r = 0.87 for interobserver correlation and r = 0.90 for intraobserver correlation.

Conclusion

Decreasing inter- and intraobserver correlation for the measurement of TT–TG with increasing severity of trochlear dysplasia was detected. In our opinion, the measurement of TT–TG is of significance in low-grade trochlear dysplasia. The final decision to perform a distal realignment procedure based on a pathological TT–TG in the presence of high-grade trochlear dysplasia should be reassessed properly.

Level of evidence

Retrospective study, Level II.     

The influence of risk factors on clinical outcomes following anatomical medial patellofemoral ligament (MPFL) reconstruction using the gracilis tendon

Purpose

Patellofemoral instability is influenced by ligamentous, boney and neuromuscular factors. The most important variables are trochlea geometry, medial patellofemoral ligament (MPFL), patella height, tibial tuberosity–trochlea groove distance (TT–TG) and the extensor muscles. Treatment is complicated by these multifactorial conditions. This prospective study examined the influence of risk factors on clinical results and athletic activities where treatment was confined to ligamentous procedures only.

Methods

Fifty patients with chronic patellofemoral instability were treated with MPFL reconstruction using an autologous gracilis tendon. Clinical data, radiographs and magnetic resonance imaging (MRI) were prospectively evaluated pre- and postoperative (minimum follow-up 12 month) to detect existing risk factors for patellofemoral instability and to evaluate clinical and sport ability scores (Kujala, Valderrabano).

Results

There was a low rate of redislocation (2 %) and an average Kujala score of 87 ± 13 points postoperative. The MRI showed good integration of the reconstructed MPFL and a positive effect regarding the decrease of patella tilt (16.1° to 11.2°). A negative relationship was found between the degree of trochlear dysplasia and outcomes. 80 % of all patients returned to the same or higher level of physical activity.

Conclusions

Addressing only ligamentous factors through MPFL reconstruction leads to satisfying clinical results and low redislocation rates in most patients. In cases with a high degree of trochlear dysplasia and enlarged TT–TG, additional procedures such as trochleaplasty and tibial tuberosity transfer should be considered as well.

Level of evidence

IV.     

Is arthroscopic surgery beneficial in treating non-traumatic, degenerative medial meniscal tears? A five year follow-up

Purpose

The aim of this prospective randomized intervention study was to evaluate the outcome at a 2 and 5 year follow-up whether combined arthroscopic surgery followed by exercise therapy was superior to the same exercise therapy alone when treating non-traumatic, degenerative medial meniscal tears.

Methods

Ninety-six middle-aged patients with MRI-verified degenerative medial meniscus tear and radiographic osteoarthritis grade ≤1 (Ahlbäck) participated in the study. Radiographic examination was done before randomization and after 5 years. The patients were randomly assigned to either arthroscopic treatment followed by exercise therapy for 2 months or to the same exercise therapy alone. At the start of the study and at the follow-ups at 24 and 60 months the patients answered three questionnaires KOOS, Lysholm Knee Scoring Scale and Tegner Activity Scale and made pain ratings on the Visual Analogue Scale (VAS).

Results

Both groups showed highly significant clinical improvements from baseline to the follow-ups at 24 and 60 months on all subscales of KOOS, Lysholm Knee Scoring Scale and VAS (p < 0.0001). No group differences were found at any of the testing occasions. One third of the patients that were treated with exercise therapy alone did not feel better after the treatment but were improved after arthroscopic surgery. According to radiographic findings two patients from each group had a slight progression of their osteoarthritis after 5 years.

Conclusion

The findings indicate that arthroscopic surgery followed by exercise therapy was not superior to the same exercise therapy alone for this type of patients. Consequently, exercise therapy can be recommended as initial treatment. However, one third of the patients from the exercise group still had disabling knee symptoms after exercise therapy but improved to the same level as the rest of the patients after arthroscopic surgery with partial meniscectomy.

Level of evidence

I.     

Combined arthroscopic deepening trochleoplasty and reconstruction of the medial patellofemoral ligament for patients with recurrent patella dislocation and trochlear dysplasia

Purpose

Prospectively, a consecutive group of patients troubled by recurrent patella dislocation and trochlear dysplasia has been followed after a combined arthroscopic deepening trochleoplasty and reconstruction of the medial patellofemoral ligament. The purpose of this follow-up study is to report the clinical results.

Methods

Indications for combined arthroscopic deepening trochleoplasty and reconstruction of the medial patellofemoral ligament were two or more patellar dislocations with a persistent apprehension sign above 20° of flexion and trochlear dysplasia grade B or more. Prospectively, the Tegner, Kujala and KOOS scores were recorded. Thirty-one consecutive patients (37 knees), 21 women and 10 men, with a median age of 19 (12–39) underwent the procedure.

Results

Results were obtained for 29 knees with a minimum of 12-month follow-up (average 29 months; range 12–57). No complications, redislocations or arthrofibrosis have been recorded. Five patients needed further surgery. The median pre- and postoperative scores (range) are as follows: Kujala 64 (12–90) to 95 (47–100); Tegner 4 (1–6) to 6 (4–9); KOOS score pain 86–94; symptoms 82–86; ADL 91–99; sport 40–86; QDL 25–81. No significant correlation was found with respect to the results and recorded parameters. Significant improvement for all of the scores was observed (p < 0.001).

Conclusions

The use of arthroscopic deepening trochleoplasty in combination with reconstruction of the medial patellofemoral ligament was found to be a safe and reproducible procedure. Considering the stability achieved, the knee scores and the patient’s level of satisfaction, the results are encouraging.

Level of evidence

Prospective consecutive case series, with evaluation of confounding factor. No control group, Level IV.     

The effect of tibio-femoral over-distraction in primary knee arthroplasty

Purpose

Overstuffing the patellofemoral joint has been associated with poor post-operative outcomes. No study has assessed the effect of over-distracting the tibio-femoral joint in the vertical plane and its effects on function and quality of life. The purpose of this study is to assess the effect of tibio-femoral joint distraction on function and quality of life after total knee arthroplasty.

Methods

Measurements of knee joint distraction were devised using long-leg alignment radiographs. Seventy-three patients were prospectively recruited and their joint distraction measured post-operatively. A comparison was made between the level of joint distraction and functional outcomes as measured by the International Knee Society score and its components, such as pain and flexion, and the Knee injury and Osteoarthritis Outcome Score and quality of life as measured by the Short-Form 12 score. Twelve-month follow-up was achieved.

Results

Knee joint over-distraction post-arthroplasty correlated significantly with Knee Society score (p = 0.041), flexion (p = 0.005) and pain (p = 0.002). Those knees that were over-distracted post-operatively suffered more pain, less flexion and a lower International Knee Society score compared with their counterparts. No correlation was found between over-distracting the knee joint and quality of life.

Conclusion

Over-distracting the tibio-femoral joint during arthroplasty is a significant predictor of reduction in function and increase in pain in the short to medium term. When between sizes of tibial inserts, the surgeon should consider using the thinner option.

Level of evidence

Prospective cohort study, Level II.