Hans Robert Springorum

The influence of component alignment on patellar kinematics in total knee arthroplasty

Background and purpose — Postoperative anterior knee pain is one of the most frequent complications after total knee arthroplasty (TKA). Changes in patellar kinematics after TKA relative to the preoperative arthritic knee are not well understood. We compared the patellar kinematics preoperatively with the kinematics after ligament-balanced navigated TKA. Patients and methods — We measured patellar tracking before and after ligament-balanced TKA in 40 consecutive patients using computer navigation. Furthermore, the influences of different femoral and tibial component alignment on patellar kinematics were analyzed using generalized linear models. Results — After TKA, the patellae shifted statistically significantly more laterally between 30° and 60°. The lateral tilt increased at 90° of flexion whereas the epicondylar distance decreased between 45° and 75° of flexion. Sagittal component alignment, but not rotational component alignment, had a significant influence on patellar kinematics. Interpretation — There are major differences in patellar kinematics between the preoperative arthritic knee and the knee after TKA. Combined sagittal component alignment in particular appears to have a major effect on patellar kinematics. Surgeons should be especially aware of altering preoperative sagittal alignment until the possible clinical relevance has been investigated.

Significant influence of rotational limb alignment parameters on patellar kinematics: an in vitro study

PurposeComponent malrotation has a major impact on patellar kinematics in total knee arthroplasty. The influence of natural rotational limb alignment on patellar kinematics is unclear so far. Based on recent clinical investigations, we hypothesized that rotational limb alignment significantly influences patellar kinematics.MethodsPatellar kinematics of ten cadaveric knees was measured using computer navigation during passive motion. Data were correlated with different rotational limb alignment parameters of preoperative CT scans.ResultsFemoral antetorsion showed a significant influence on patellar rotation, while tibial tubercle–posterior cruciate ligament distance additionally displayed a significant influence on patellar mediolateral shift (pxa0<xa00.05). Femoral posterior condylar angle was sensitive to patellar epicondylar distance, rotation and tilt (pxa0<xa00.05). Patellar rotation was influenced by five out of eight rotational limb alignment parameters (pxa0<xa00.05).ConclusionsRotational limb alignment should be paid more attention in terms of clinical evaluation of patellar tracking and future biomechanical and clinical investigations.

Changes in sagittal component alignment alters patellar kinematics in TKA: an in vitro study

PurposePatellar maltracking due to incorrect component alignment is considered as a main reason for anterior knee pain after total knee arthroplasty (TKA). In contrast to coronal and axial component placement, the influence of sagittal component alignment on patellar kinematics has not been investigated so far.MethodsIn ten lower cadaveric limbs, TKAs were implanted using a commercial computer navigation system. In six knees, the femoral component was aligned in 5° and in four knees in 0° of flexion, respectively. Patellar kinematics were registered by means of a computer navigation system using an additional patella tracking array and correlated with femoral and tibial sagittal component alignment.ResultsSagittal component alignment significantly altered patellar mediolateral shift (pxa0<xa00.05). In contrast, patellar epicondylar distance, rotation and tilt were not significantly influenced.ConclusionsSagittal component alignment in TKA has a major impact on patellar kinematics and should therefore be considered while addressing tibiofemoral kinematics intraoperatively.

Lower Limb Anatomy and Alignment Affect Natural Tibiofemoral Knee Kinematics: A Cadaveric Investigation

BACKGROUNDnDuring flexion, normal knee kinematics consists of a complex combination of rolling, gliding, and rotation between femur and tibia. Although inxa0vivo studies have shown wide interindividual variability, we hypothesized that knee kinematics is either correlated to the anatomy of the individual knee joint or to the anatomic alignment of the entire lower extremity.nnnMETHODSnThe passive kinematics of 10 healthy knees was assessed in whole cadavers using a commercial computed tomography-free navigation device with intracortical pins. Rotational limb alignment or local anatomic parameters obtained by computed tomography scan or within a navigational procedure were correlated to tibial internal rotation and tibiofemoral abduction during flexion.nnnRESULTSnMean tibial adduction in full extension was 3.3° (rangexa0-2.2° to 7.8°). Tibial abduction and internal rotation showed significant interindividual variability, measuring 3.9° (rangexa0-0.8° to 9.7°) and 4.9° (rangexa0-3.5° to 14.8°) during flexion. An increase in both the mechanical tibiofemoral axis and the mechanical lateral distal femoral angle correlated with increased tibial internal rotation, whereas a decrease in the mechanical medial proximal tibial angle and an increase in the mechanical tibiofemoral axis were associated with increased tibial adduction.nnnCONCLUSIONnThe main finding of the present study is that knee kinematics is influenced by both intra-articular and extra-articular parameters. These results may be of interest in component alignment in total knee arthroplasty, correction of deformities, and malalignment after fracture healing of the lower extremity. Possible relationships should be investigated in future studies.

No difference between standard and high flexion cruciate retaining total knee arthroplasty: a prospective randomised controlled study

AbstractPurposenThe purpose of this prospective, randomised, double-blind study was to test the hypotheses that patients with high-flexion total knee arthroplasty (TKA) have (1) a wider/greater range of motion (ROM) post-operatively and (2) higher levels of knee society score (KSS) and WOMAC score post-operatively compared to standard TKA.MethodsIn this study, 28 high flexion with 31 standard TKAs were compared. We measured ROM, pre-operatively, on day 3, 7, 28, and after 6 and 36xa0months post-operatively as well as KSS and WOMAC score pre-operatively, on day 28 and after 6 and 36xa0months post-operatively.ResultsNo statistically significant differences were found between both groups with regard to the target parameters. The mean ROM was 113° (range 80°–140°, SD 13.4°) in the control group (standard TKA) and 117° (range 90°–140°, SD 12.3) in the study group (high-flexion TKA) at 36xa0months follow-up [pxa0=xa0not significant (n.s.)]. The KSS pre-operatively was 38.2 (range 8–64, SD 15.8) in the control group and 45.9 (range 8–74, SD 16.0) in the study group (n.s.) increasing to 157.6 in the control group and 156.7 in the study group (pxa0=xa0n.s) at 36xa0months follow-up.ConclusionThis study could not confirm significant benefits of high-flexion TKA compared to standard TKA with regard to ROM and higher levels of KSS and WOMAC score.Level of evidenceI.

Do surgical patellar interventions restore patellar kinematics in fixed-bearing, cruciate-retaining total knee arthroplasty?: An in vitro study

Despite different surgical patellar interventions, the decision how to treat the patella during TKA remains controversial. The purpose of this study was to quantify the effect of different reconstructive patellar interventions on patellar kinematics during TKA using optical computer navigation. We implanted ten navigated TKAs in full body specimens. During passive motion, the effect of different surgical patellar interventions on patellar kinematics was analysed. A contrarily tilt behaviour was observed in the TKA group without patellar intervention compared to the natural knee. Lateral release led to similar tilt values (P < 0.05). All surgical interventions led to a 3 to 5mm medial shift of the patella (P < 0.05). None of the analysed surgical patellar interventions could restore natural patellar kinematics after TKA.

Is it possible to re-establish pre-operative patellar kinematics using a ligament-balanced technique in total knee arthroplasty? A cadaveric investigation

PurposeSeveral authors emphasise that the appearance of patellar maltracking after total knee arthroplasty (TKA) is caused by rotational malalignment of the femoral and tibial components. Ligament-balanced femoral component rotation was not found to be associated with abnormal postoperative patellar position. We hypothesised that a ligament-balanced technique in TKA has the ability to best re-establish patellar kinematics.MethodsIn ten cadaveric knees TKA was performed assessing femoral rotation in ligament-balanced and different femoral and tibial component rotation alignments. Patellar kinematics after different component rotations were analysed using a commercial computer navigation system.ResultsLigament-balanced femoral rotation showed the best re-establishment of patellar kinematics after TKA compared to the healthy pre-operative knee. In contrast to tibial component rotation, femoral component rotation had a major impact on patellofemoral kinematics.ConclusionsThis investigation suggests that a ligament-balanced technique in TKA is most likely to re-establish natural patellofemoral kinematics. Tibial component rotation did not influence patellar kinematics.

Current therapeutic strategies of heterotopic ossification – a survey amongst orthopaedic and trauma departments in Germany

BackgroundHeterotopic ossification (HO) is a complication after tissue trauma, fracture and surgery (i.e. total hip arthroplasty). Prophylaxis is the most effective therapy. If HO formations become symptomatic and limit patients’ quality of life, revision surgery is indicated and is usually combined with a perioperative oral prophylaxis (NSAIDs) and/or irradiation. However, a long-term use of NSAIDs can induce gastro-intestinal or cardiac side-effects and possible bony non-unions during fracture healing. Subject of this study was to assess the current status of HO prophylaxis after injuries or fractures and to evaluate current indications and strategies for excision of symptomatic HO.MethodsBetween 2013 and 2014, a questionnaire was sent to 119 orthopaedic and trauma surgery departments in Germany. Participation was voluntary and all acquired data was given anonymously.ResultsThe cumulative feedback rate was 71xa0%. Trauma and orthopaedic surgery departments in Germany recommend oral HO prophylaxis after acetabulum and femoral neck fractures, elbow dislocation, and fracture or dislocation of the radial head. Pain upon movement and an increasing loss of range of motion in the affected joint are considered to be clear indications for HO surgery. A partial removal of ROM-limiting HO formations was also considered important. The vast majority of all departments include perioperative oral HO prophylaxis and/or irradiation if surgical HO removal is planned. The choice and duration of NSAIDs is highly variable.ConclusionHO is of clinical significance in current traumatology and orthopaedics. Certain fractures and injuries are prone to HO, and prophylactic measures should be taken. The respondents in this survey assessed current therapeutic strategies for HO formations similarly. These concepts are in line with the literature. However, the duration of perioperative oral HO prophylaxis varied greatly among the specialist centres. This is significant as a long-term use of NSAIDs fosters a potential risk for the patients’ safety and could influence the clinical outcome. National and international guidelines need to be developed to further reduce HO rates and improve patients’ safety in trauma and orthopaedic surgery.

In-Vitro Investigation of a Noninvasive Referencing Technology for Computer-assisted Total Hip Arthroplasty

The use of surgical navigation to aid in total joint replacement requires the bony fixation of reference marker arrays. In this context, a number of potential complications have been reported, including pin-site infection, soft tissue morbidity, and stress fracture. This study was performed to determine whether a femoral pinless, imageless navigation method for total hip arthroplasty (THA) is an accurate alternative method of measuring leg-length and offset change intraoperatively. Computer-assisted THA was simulated on a Sawbones bench test model including a femoral soft tissue model. Leg-length and offset changes were calculated by an imageless navigation system using the pinless measurement algorithm, in which the calculation of leg-length and offset changes is based on a specific realignment of the leg and then compared to corresponding measurements on a millimeter scale at the level of the femoral condyles. Mean difference in leg-length measurement (navigation versus millimeter paper) was 0.9 mm (95% confidence interval [CI]: 0.03-1.7 mm, P=.043), and the corresponding mean difference in offset was 1 mm (95% CI: 0.06-1.9 mm, P=.038). A noninvasive, pinless femoral system is a reliable tool for controlling leg length and offset during THA in an in-vitro setup. This system could lead to a reduction of potential risks associated with navigation techniques.

Influence of Component Rotation in Total Knee Arthroplasty on Tibiofemoral Kinematics—A Cadaveric Investigation

BACKGROUNDnPhysiological tibiofemoral kinematics have been shown to be important for good knee function after total knee arthroplasty (TKA). The purpose of the present study was to investigate the influence of component rotation on tibiofemoral kinematics during knee flexion. We asked which axial component alignment best reconstructs physiological tibiofemoral kinematics and which combinations should be avoided.nnnMETHODSnTen healthy cadaveric knees were examined. By means of a navigational device, tibiofemoral kinematics between 0° and 90° of flexion were assessed before and after TKA using the following different rotational component alignment: femoral components: ligament balanced, 6° internal, 3° external rotation, and 6° external rotation in relation to the posterior condylar line; tibial components: self-adapted, 6° internal rotation, and 6° external rotation.nnnRESULTSnPhysiological tibiofemoral kinematics could be partly reconstructed by TKA. Ligament-balanced femoral rotation and 6° femoral external rotation both in combination with 6° tibial component external rotation, and 3° femoral external rotation in combination with 6° tibial component internal rotation or self-aligning tibial component were able to restore tibial longitudinal rotation. Largest kinematical differences were found for the combination femoral component internal and tibial component external rotations.nnnCONCLUSIONnFrom a kinematic-based view, surgeons should avoid internal rotation of femoral components. However, even often recommended combinations of rotational component alignment (3° femoral external and tibial external rotation) significantly change tibiofemoral kinematics. Self-aligning tibial components solely restored tibiofemoral kinematics with the combination of 3° femoral component of external rotation. For the future, navigational devices might help to axially align components to restore patient-specific and natural tibiofemoral kinematics.