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.     

Combined ACL reconstruction and closing-wedge HTO for varus angulated ACL-deficient knees

Purpose

To report the medium-term clinical and radiographic outcomes of a group of patients who underwent anterior cruciate ligament (ACL) surgery combined with high tibial osteotomy (HTO) for varus-related early medial osteoarthritis (OA) and ACL deficiency knee.

Methods

Thirty-two patients underwent single-bundle over-the-top ACL reconstruction or revision surgery and a concomitant closing-wedge lateral HTO. The mean age at surgery was 40.1 ± 8.1 years. Evaluation at a mean of 6.5 ± 2.7 years of follow-up consisted of subjective and objective IKDC, Tegner Activity Level, EQ-5D, VAS for pain and AP laxity assessment with KT-1000 arthrometer. Limb alignment and OA changes were evaluated on radiographs.

Results

All scores significantly improved from pre-operative status to final follow-up. KT-1000 evaluation showed a mean side-to-side difference of 2.2 ± 1.0 mm. Two patients were considered as failures. The mean correction of the limb alignment was 5.6° ± 2.8°. Posterior tibial slope decreased at a mean of 1.2° ± 0.9°. At final follow-up, the mechanical axes crossed the medial–lateral length of tibial plateau at a mean of 56 ± 23 %, with only 1 patient (3 %) presenting severe varus alignment. OA progression was recorded only on the medial compartment (p = 0.0230), with severe medial OA in 22 % of the patients. No patients underwent osteotomy revision, ACL revision, UKA or TKA.

Conclusions

The described technique allowed patients with medial OA, varus alignment and chronic ACL deficiency to restore knee laxity, correct alignment and resume a recreational level of activity at 6.5 years of follow-up.

Level of evidence

Case series with no comparison group, Level IV.     

Relationship between muscle volume and muscle torque of the hamstrings after anterior cruciate ligament lesion

Purpose

This study was conducted to identify factors other than morphological muscle strength factors that affect injured and uninjured sides of knee flexors with anterior cruciate ligament (ACL) lesions.

Methods

The study population consisted of 22 patients with ACL lesions. Their hamstring muscle volume was measured on MRI, and muscle torque per muscle volume was calculated as the peak torque of knee flexion divided by hamstring muscle volume.

Results

The mean muscle torque per unit volume of hamstrings in patients with ACL rupture was 0.09 ± 0.02 Nm/cm³ at 60°/s and 0.08 ± 0.01 Nm/cm³ at 180°/s on the injured side, and 0.11 ± 0.02 Nm/cm³ at 60°/s and 0.08 ± 0.01 Nm/cm³ at 180°/s on the uninjured side. The mean muscle torque per unit volume of hamstrings in control subjects was 0.11 ± 0.02 Nm/cm³ at 60°/s and 0.08 ± 0.03 Nm/cm³ at 180°/s. One-factor ANOVA analysis found no significant differences between the three groups at either flexion velocity.

Conclusions

Neurological dysfunction does not appear to exist in knee flexor muscles after ACL injury, unlike the quadriceps. Since the mechanism of muscle weakness will differ depending on the muscle, it is important for clinicians to take this discrepancy into consideration.

Level of evidence

II.     

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.     

The minimally invasive far medial subvastus approach for total knee arthroplasty in valgus knees

Purpose

The lateral approach in the valgus knee asks for a lot of soft tissue releases during the arthrotomy. The hypothesis of this study was that the far medial subvastus approach could be used in valgus knees and would guarantee both functional and radiological good to excellent results.

Methods

This is a retrospective study on 78 patients (84 knees) undergoing primary total knee arthroplasty (TKA) for type I or II fixed valgus knees. The mean (SD) preoperative mechanical alignment was 187° (4°) HKA angle. Functional recovery, pain, tourniquet times, necessary soft tissue releases as well as radiological alignment were measured.

Results

The Knee Score improved significantly from 45 (10) to 90 (10) (P < 0.05) and the function score improved as well from 35 (20) to 85 (10) (P < 0.05). Flexion improved from 110° (10°) to 137° (8°). Hospital stay was 4 (1.2) days. Alignment was corrected to 181° (1.5°) HKA angle with a postoperative joint line shift of +2.8 (3.2) mm. No clinical instability, as evaluated by the senior author, or osteolytic lines was observed at minimal one-year radiological follow-up.

Conclusion

The far medial subvastus approach is an excellent approach to perform Krackow type I and II TKA with primary PS implants.

Level of evidence

IV.     

Varus femoral and tibial coronal alignments result in different kinematics and kinetics after total knee arthroplasty

Purpose

Abnormal knee motion under various conditions has been described after total knee arthroplasty (TKA). However, differences in kinematics and kinetics of knees with varus femoral versus varus tibial alignment have not been evaluated. It was hypothesized that varus femoral and tibial alignments have the same impact on knee motion.

Methods

A musculoskeletal computer simulation was used. Femoral and tibial alignment in the coronal plane was each varied from neutral to 5° of varus in 1° increments. Lift-off, defined as an intercomponent distance of >2 mm, and tibiofemoral contact forces were evaluated during gait up to 60° of knee flexion. Knee kinematics and contact stresses were also examined during squat, with up to 130° of knee flexion.

Results

During gait, lift-off occurred readily with more than 3° of varus tibial alignment and slight lateral joint laxity. In contrast, lift-off did not occur with varus femoral or tibial alignment of up to 5° during squat. Peak medial contact forces with varus femoral alignment were approximately twice those observed with varus tibial alignment. The lowest points of the femoral condyles moved internally with varus femoral alignment, contrary to the kinematics with neutral or varus tibial alignment. On the other hand, there was femoral medial sliding and edge loading against the tibia in mid-flexion with varus tibial alignment.

Conclusion

Varus femoral alignment affects the non-physiological rotational movement of the tibiofemoral joint, whereas varus tibial alignment causes medial–lateral instability during mid-flexion. Varus femoral and tibial alignments might lead to post-TKA discomfort and unreliability.

     

Restoring tibiofemoral alignment during ACL reconstruction results in better knee biomechanics

Purpose

Anterior cruciate ligament (ACL) reconstruction (ACLR) aims to restore normal knee joint function, stability and biomechanics and in the long term avoid joint degeneration. The purpose of this study is to present the anatomic single bundle (SB) ACLR that emphasizes intraoperative correction of tibiofemoral subluxation that occurs after ACL injury. It was hypothesized that this technique leads to optimal outcomes and better restoration of pathological tibiofemoral joint movement that results from ACL deficiency (ACLD).

Methods

Thirteen men with unilateral ACLD were prospectively evaluated before and at a mean follow-up of 14.9 (SD?=?1.8) months after anatomic SB ACLR with bone patellar tendon bone autograft. The anatomic ACLR replicated the native ACL attachment site anatomy and graft orientation. Emphasis was placed on intraoperative correction of tibiofemoral subluxation by reducing anterior tibial translation (ATT) and internal tibial rotation. Function was measured with IKDC, Lysholm and the Tegner activity scale, ATT was measured with the KT-1000 arthrometer and tibial rotation (TR) kinematics were measured with 3Dmotion analysis during a high-demand pivoting task.

Results

The results showed significantly higher TR of the ACL-deficient knee when compared to the intact knee prior to surgery (12.2° ± 3.7° and 10.7° ± 2.6° respectively, P?=?0.014). Postoperatively, the ACLR knee showed significantly lower TR as compared to the ACL-deficient knee (9.6°±3.1°, P?=?0.001) but no difference as compared to the control knee (n.s.). All functional scores were significantly improved and ATT was restored within normal values (P?<?0.001).

Conclusions

Intraoperative correction of tibiofemoral subluxation that results after ACL injury is an important step during anatomic SB ACLR. The intraoperative correction of tibiofemoral subluxation along with the replication of native ACL anatomy results in restoration of rotational kinematics of ACLD patients to normal levels that are comparable to the control knee. These results indicate that the reestablishment of tibiofemoral alignment during ACLR may be an important step that facilitates normal knee kinematics postoperatively.

Level of evidence

Level II, prospective cohort study.

     

The difference between weight-bearing and non-weight-bearing alignment in patient-specific instrumentation planning

Purpose

Retrospective study to analyse the difference between weight-bearing and non-weight-bearing alignment in osteoarthritic knees planned for patient-specific instrumented (PSI) total knee arthroplasty (TKA). The aim of the study is to observe whether a difference in alignment can be linked to arthritis staging or zone mechanical axis.

Methods

Full-leg standing radiographs and non-weight-bearing MRI of the whole leg were compared for hip–knee–ankle (HKA) angle, measured according to Moreland criteria, in seventy osteoarthritic patients. Kellgren–Lawrence (KL) staging and classification according to zone mechanical axis with Kennedy zones was done.

Results

A mean preoperative HKA angle on standing radiographs of 176.4° ± 7.2° was measured compared to 176.4° ± 6.9° for the MRI whole-leg HKA angle. A difference of 0°–1° was observed in 54 % of patients when comparing the weight-bearing with the non-weight-bearing HKA angle. Twenty-three per cent had a difference of 2° and another 23 % a difference of 3° or more. In female patients, the dynamic load pattern of weight-bearing increases the HKA angle due to convex side soft tissue laxity both in varus and valgus knees. More important differences were observed in the KL stage 3 and 4 patients (P < 0.05) and with a load-bearing axis outside of the articular surface (P < 0.05).

Conclusion

Surgeons should be aware that there is a difference between weight-bearing and non-weight-bearing alignment in patients with Kellgren–Lawrence 3 and 4 with a load-bearing axis outside of the articular surface (Kennedy 0 or 1 or 5). According to this study, these changes seem related to the amount of articular wear and the load-bearing axis. This is important for the preoperative planning process in PSI-assisted TKA. More concave side ligamentous release or more constraint can be necessary than imagined based on the PSI alignment result. Full-leg standing radiographs should be performed for PSI-assisted TKAs to analyse the position of the load-bearing axis.

Level of evidence

IV.     

Long-term follow-up of ACL reconstruction with hamstring autograft

Purpose

To investigate the differences in the incidence and severity of knee osteoarthritis (OA), joint space narrowing, knee laxity, and knee flexion and extension strength between an anterior cruciate ligament (ACL)-reconstructed knee and the contralateral non-reconstructed limb.

Methods

Retrospective case series of patients from a single surgeon that had an ACL reconstruction with a semitendinosus/gracilis autograft more than 12 years ago. Outcome measures included radiographic analysis, International Knee Documentation Committee Subjective Knee Evaluation Form (IKDC), KT-1000, Tegner Activity Level Scale, Lysholm Knee Score, ACL quality of life score (ACL-QOL) and knee flexor/extensor strength.

Results

Seventy-four patients consented and sixty-eight (43 male, 25 female) were included for analysis. Average age (SD) at the time of surgery was 31.2 (±9.1) years. At follow-up of 14.6 (1.9) years, 9 % had re-ruptured their ACL, whereas 5 % ruptured the contralateral ACL. Reconstructed knees had a greater incidence and severity of OA (P < 0.01). Medial meniscus surgery was a strong predictor of OA. Seventy-five per cent scored a normal or nearly normal knee on the IKDC. The mean Lysholm score was 75.8 % and Tegner Activity Level Scale scores decreased (P < 0.001) from the time of surgery. Knee extension strength was greater in the contralateral knee at speeds of 60°/s (P = 0.014) and 150°/s (P = 0.012).

Conclusions

Reconstructed knees have a greater incidence and severity of OA than non-reconstructed knees, which suggests degenerative changes are secondary to ACL rupture. Medial meniscus surgery is a strong predictor of OA. Despite this, 75 % of patients reported good outcomes.     

Patellar thickness and lateral retinacular release affects patellofemoral kinematics in total knee arthroplasty

Purpose

To study the effect of increasing patellar thickness (overstuffing) on patellofemoral kinematics in total knee arthroplasty and whether subsequent lateral retinacular release would restore the change in kinematics.

Methods

The quadriceps of eight fresh-frozen knees were loaded on a custom-made jig. Kinematic data were recorded using an optical tracking device for the native knee, following total knee arthroplasty (TKA), then with patellar thicknesses from ?2 to +4 mm, during knee extension motion. Staged lateral retinacular releases were performed to examine the restoration of normal patellar kinematics.

Results

Compared to the native knee, TKA led to significant changes in patellofemoral kinematics, with significant increases in lateral shift, tilt and rotation. When patellar composite thickness was increased, the patella tilted further laterally. Lateral release partly corrected this lateral tilt but caused abnormal tibial external rotation. With complete release of the lateral retinaculum and capsule, the patella with an increased thickness of 4 mm remained more laterally tilted compared to the TKA with normal patellar thickness between 45° and 55° knee flexion and from 75° onwards. This was on average by 2.4° ± 2.9° (p < 0.05) and 2.°9 ± 3.0° (p < 0.01), respectively. Before the release, for those flexion ranges, the patella was tilted laterally by 4.7° ± 3.2° and 5.4° ± 2.7° more than in the TKA with matched patellar thickness.

Conclusion

Patellar thickness affects patellofemoral kinematics after TKA. Although lateral tilt was partly corrected by lateral retinacular release, this affected the tibiofemoral kinematics.

Level of evidence

IV.     

Decreased femoral head–neck offset: a possible risk factor for ACL injury

Purpose

Reduction in anterior cruciate ligament (ACL) injuries in young, active individuals continues to be a major goal in sports medicine. The purpose of this study was to determine the head–neck offset, as measured by AP pelvis alpha angles, in patients presenting to a single surgeon with isolated ACL and non-ACL knee injuries.

Methods

In a group of 48 patients with complete, primary ACL rupture and 42 controls with non-ACL injury (i.e., meniscus tear, cartilage defect), a single surgeon, blinded to the diagnosis, took radiographic measures of the AP alpha angle of both hips and the weight-bearing line at both knees. All knee pathology was confirmed with knee arthroscopy. Inclusion criteria included no previous hip or knee surgery, and long-leg standing alignment radiographic series completed at index visit.

Results

There was no difference in gender distribution, height, BMI or age between groups. ACL-injured patients had a significantly higher alpha angle (mean = 84, SD = 14) on the injured side than the controls (mean = 59, SD = 7, p < 0.0001). Ninety-four percent of the ACL-injured group had alpha angles over 60°, while only 35% of the non-ACL-injured group had alpha angles over 60° (p = 0.001). Those patients with alpha angle over 60° were 27 times more likely (95% CI 6.4–131) to be in the ACL injury group than those patients with alpha angle 60° or less (p = 0.001).

Conclusion

Our findings establish an important preliminary correlation between ACL injury and diminished femoral head–neck offset, as characterized by abnormal, elevated alpha angles.

Level of evidence

Prognostic study, Level III.     

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.     

Evaluation of a new low-dose biplanar system to assess lower-limb alignment in 3D: a phantom study

Objective

Knee coronal alignment is routinely assessed on a full-length radiograph of the lower limbs. However, poor positioning of the knee during the procedure affects the accuracy of this kind of measurement, particularly in cases combining knee rotation and flexion. The purpose of this study was to assess the value of a three-dimensional assessment of the hip-knee-ankle (HKA) angle based on a biplanar radiographic system.

Materials and methods

A biplanar slot scanning system was used to take radiographs of three lower-limb synthetic models with similar frontal deviation (5°valgus) but different flexion angulations (0°, 9°, and 18°). Biplane acquisitions were done with lower-limb axial rotations ranging from 20° of internal rotation to 20° of external rotation on each of the lower limb models. Three independent observers performed standard 2D measurements of the HKA angle from each anteroposterior (AP) image and also modeled the lower limb in 3D for each biplane acquisition with dedicated software. The HKA angle was automatically calculated from the 3D models. The results of the 2D and 3D techniques were compared.

Results

Axial rotation provoked 2D HKA measurement errors up to, respectively, 1.4°, 4.7°, and 6.8° for the lower extremities with 0°, 9°, and 18° flexion, while it never affected the 3D HKA measurement for more than 1.5°. Interobserver errors were 0.7° (SD?=?0.5°) for the 2D measurements and 0.6° (SD?=?0.4°) for the 3D measurements.

Conclusions

The 3D modeling allows for a more accurate evaluation of coronal alignment compared to 2D, eliminating bias due to wrong knee positioning.     

Variations in kinematics and function following patellar stabilization including tibial tuberosity realignment

Purpose

The current study was performed to characterize the influence of patellar stabilization procedures on patellofemoral and tibiofemoral dynamic motion.

Methods

Six knees were evaluated pre-operatively and 1 year or longer following stabilization via tibial tuberosity realignment, with simultaneous medial patellofemoral ligament reconstruction performed for five knees. Knees were imaged during extension against gravity using a dynamic CT scanner. Models representing each knee at several positions of extension were reconstructed from the images. Local coordinate systems were created within one femur, patella and tibia for each knee, with shape matching of the bones used to transfer the coordinate axes to the other models. The patellar lateral shift and tilt and tibial external rotation were quantified based on the reference axes and interpolated to flexion angles from 5° to 40°. Pre-operative and post-operative data were compared with the paired t tests.

Results

Surgical realignment significantly decreased the average patellar lateral shift and tilt at low flexion angles. At 5°, surgical realignment decreased the average lateral shift from 15.5 (6.3) to 8.5 (4.7) mm and decreased the average lateral tilt from 20.8 (9.4)° to 13.8 (6.4)°. The changes were statistically significant (p < 0.05) at 5° and 10° of flexion, as well as 20° for lateral shift. The average tibial external rotation also increased significantly at 30° and 40° following surgery.

Conclusion

Patellar stabilization including a component of tuberosity realignment reduces patellar lateral shift and tilt at low flexion angles, but the long-term influence of increased tibial external rotation on tibiofemoral function is currently unknown.

Level of evidence

Prospective comparative study, Level II.     

Arthroscopic evaluation of knee lateral compartment widening after lateral ligamentous injury

Purpose

To evaluate whether diagnostic arthroscopy of the lateral tibiofemoral compartment can determine the presence of a lateral ligamentous knee injury.

Methods

Nine cadaveric knee specimens were used with varus stresses of 12 Nm and the force at which no further lateral opening occurred. Arthroscopic measurements were taken of the lateral compartments with knees at 30°, 45° and 90°. Measurements were recorded in the intact knees and with sequential sectioning of LCL, popliteus, popliteofibular, ACL and PCL. Measurements and opening differences between each ligament state were recorded.

Results

No significant difference existed between the two forces compared (p < 0.05). There was a significant difference in opening distance measured at all knee angles with sequential sectioning (p < 0.001). Sequential opening difference between each ligament state was significantly different (p < 0.001) and also when compared across each knee angle (p < 0.001). At 30° for an isolated LCL injury, the average lateral opening was 10.1 mm. For a combined LCL and PLC (popliteus tendon and popliteofibular ligament) injury, the average lateral opening was 12.9 mm. For LCL-, PLC- and ACL-deficient knees, there was average lateral opening of 16.5 mm.

Conclusions

LCL and combined lateral ligamentous injuries can be differentiated during arthroscopy with varus stress. This may be useful when deciding if there is a need for operative repair of any injured lateral ligamentous structures.     

Does varus alignment increase after medial meniscectomy?

Purpose

In patients who underwent arthroscopic meniscectomy for medial meniscus tears, the authors wished to ascertain (1) whether varus alignment in the lower extremity would increase after an operation and (2) if so, what the related factors would be.

Methods

Among 181 patients from 20 to 60 years of age who underwent arthroscopic medial meniscectomy for medial meniscus tears between 2002 and 2005, 56 patients followed for a minimum period of 5 years were enroled for this study. Alignment in the lower extremity was measured preoperatively and again at the last follow-up. Change in varus alignment (the difference between preoperative alignment and alignment at the last follow-up) was analyzed in relation to sex, age, body mass index (BMI), resection amount (partial vs. total), preoperative alignment, and follow-up duration, using multiple linear regression analysis.

Results

Varus deformity increased by 1.7° ± 1.5° from a preoperative mean of 2.4° ± 2.4° to a mean of 4.1° ± 3.0° at the last follow-up, which was statistically significant (p = 0.000). From multiple linear regression analysis, only the resection amount (partial meniscectomy or total meniscectomy) was found to be significantly related to the change in varus alignment (p = 0.002). Other factors including sex, age, BMI, preoperative alignment, presence of cartilage injury and follow-up duration were not significantly related to the change in varus alignment after the operation.

Conclusions

Arthroscopic meniscectomy performed in patients with medial meniscus tears aggravated varus alignment in the lower extremity at the last follow-up. In addition, the increase in varus deformity was significantly higher among patients with total meniscectomy than among those with partial meniscectomy.

Level of evidence

Retrospective comparative study, Level III.     

Is osteoarthritis an inevitable consequence of anterior cruciate ligament reconstruction? A meta-analysis

Purpose

Although the occurrence of early osteoarthritis (OA) is commonly associated with a history of anterior cruciate ligament (ACL) reconstruction, its exact prevalence in these patients remains unknown. The goal of this study was to review the current literature on long-term radiographic outcome after autologous ACL reconstruction and subsequently perform a meta-analysis to obtain evidence-based prevalences of OA at a mean of 10 years after surgery. In addition, this report aimed at identifying the relationship between meniscal status and the occurrence of radiographic OA in the ACL reconstructed knee.

Methods

A systematic review of the literature was performed in PubMed MEDLINE, EMBASE and Cochrane Library databases to identify all studies concerning radiographic outcome after autologous ACL reconstruction with a follow-up of minimum 10 years. Meta-analyses were performed to obtain the average prevalence of OA and the difference between patients with and without meniscectomy. Considered study estimates were the log-transformed odds and odds ratios, the latter expressing the effect of meniscectomy on OA.

Results

A total of 16 studies could be included for meta-analysis, accounting for 1554 ACL reconstructions performed between 1978 and 1997. Of these knees, 453 (28 %) showed radiological signs of osteoarthritis (IKDC grade C or D). Furthermore, 50 % of the patients with meniscectomy had osteoarthritis, compared with 16 % of the patients without meniscectomy. The combined odds ratio for meniscectomy equals 3.54 (95 % CI 2.56–4.91).

Conclusions

The main finding of this meta-analysis is that the prevalence of radiographic knee OA after ACL reconstruction is lower than commonly perceived. However, associated meniscal resection dramatically increases the risk for developing OA.

Level of evidence

Level III.     

Prospective clinical and radiological two-year results after patellofemoral arthroplasty using an implant with an asymmetric trochlea design

Purpose

The purpose was to prospectively evaluate the two-year results after implantation of the Journey PFJ^® (Smith & Nephew, Andover, MA). The authors hypothesized that patellofemoral arthroplasty would result in improved outcomes after 24 months in patients treated with an isolated procedure as well as in patients demonstrating concomitant patellofemoral instability (PFI), which were treated with a combined surgical procedure.

Methods

Patients were included between 02/2006 and 08/2008. According to the history and clinical findings, patients were grouped into group I with no history or clinical signs of PFI, and patients with concomitant PFI were assorted to group II. Patients were then treated with an isolated (group I) or a combined (group II) surgical procedure to additionally treat the PFI. Visual analogue scale (VAS), Lysholm score and WOMAC score were recorded preoperatively, 6, 12 and 24 months postoperatively. Patellar height was evaluated according to the index of Caton-Deschamps (CDI), and osteoarthritic changes were evaluated according to Kellgren and Lawrence.

Results

A total of 25 patients were enrolled, of them three discontinued interventions and were excluded from final analysis. An isolated implantation of the Journey PFJ^® was performed in 14 patients (group I) and a combined procedure in 8 (group II). Daily pain and clinical scores significantly improved at 6, 12 and 24 months compared to preoperative values (P < 0.05). Significant decrease (P = 0.02) of mean CDI could be noticed. Significant increase in tibiofemoral OA within the medial but not in the lateral tibiofemoral joint was assessed (P = 0.011; n.s.).

Conclusions

Patellofemoral arthroplasty using the Journey^® PFJ for treatment of significant patellofemoral OA demonstrated improved clinical scores at the 2-year follow-up in both groups. Comparing the primary OA (I) and OA + instability (II) groups, patients with patellofemoral OA treated with a combined procedure for concomitant stabilization of patellofemoral instability may benefit more from such a combined procedure, than patients treated with an isolated procedure for treatment of isolated patellofemoral OA.

Level of evidence

Prospective case series, Level III.     

Restoration of sagittal and transverse plane proprioception following anatomic double-bundle ACL reconstruction

Purpose

To investigate the restoration of knee proprioception after anatomic double-bundle ACL reconstruction.

Methods

Eleven subjects who underwent anatomic double-bundle ACL reconstruction (12.5–15 months following surgery) and eleven healthy control subjects participated in the study. Sagittal and transverse plane threshold to detect passive motion (TTDPM) were assessed utilizing a customized isokinetic dynamometer by passively rotating the tibia about a fixed femur in both the sagittal plane and transverse plane at 0.25°/s until the subject signalled recognition of movement and movement direction. Based on the normality assumption, either dependent t test or Wilcoxon test was utilized to determine whether significant differences were present between the ACL-reconstructed and the uninjured contralateral limbs. Independent t test or Mann–Whitney test was utilized to compare between the ACL-reconstructed/uninjured contralateral and the external control limbs.

Results

There were no significant differences in TTDPM measurement in eleven out of twelve comparisons between the ACL-reconstructed and the uninjured contralateral/external control limbs. The only statistical significant difference was found on TTDPM towards internal rotation direction from the externally rotated-test position between the ACL-reconstructed and the uninjured contralateral limbs (p = 0.01).

Conclusions

Based on a small sample of eleven subjects, the current results indicate a restoration of both sagittal and transverse plane TTDPM following the anatomic double-bundle ACL reconstruction.

Level of evidence

III.     

Tibial component alignment and risk of loosening in unicompartmental knee arthroplasty: a radiographic and radiostereometric study

Purpose

Unicompartmental knee arthroplasty (UKA) has shown a higher rate of revision compared with total knee arthroplasty. The success of UKA depends on prosthesis component alignment, fixation and soft tissue integrity. The tibial cut is the crucial surgical step. The hypothesis of the present study is that tibial component malalignment is correlated with its risk of loosening in UKA.

Methods

This study was performed in twenty-three patients undergoing primary cemented unicompartmental knee arthroplasties. Translations and rotations of the tibial component and the maximum total point motion (MTPM) were measured using radiostereometric analysis at 3, 6, 12 and 24 months. Standard radiological evaluations were also performed immediately before and after surgery. Varus/valgus and posterior slope of the tibial component and tibial–femoral axes were correlated with radiostereometric micro-motion. A survival analysis was also performed at an average of 5.9 years by contacting patients by phone.

Results

Varus alignment of the tibial component was significantly correlated with MTPM, anterior tibial sinking, varus rotation and anterior and medial translations from radiostereometry. The posterior slope of the tibial component was correlated with external rotation. The survival rate at an average of 5.9 years was 89 %. The two patients who underwent revision presented a tibial component varus angle of 10° for both.

Conclusions

There is correlation between varus orientation of the tibial component and MTPM from radiostereometry in unicompartmental knee arthroplasties. Particularly, a misalignment in varus larger than 5° could lead to risk of loosening the tibial component.

Level of evidence

Prognostic studies—retrospective study, Level II.