Martin Michael Wachowski

Patellar dislocations in children, adolescents and adults: A comparative MRI study of medial patellofemoral ligament injury patterns and trochlear groove anatomy

PURPOSE The first aim was to compare medial patellofemoral ligament injury patterns in children and adolescents after first-time lateral patellar dislocations with the injury patterns in adults. The second aim was to evaluate the trochlear groove anatomy at different developmental stages of the growing knee joint. MATERIALS AND METHODS Knee magnetic resonance (MR) images were collected from 22 patients after first-time patellar dislocations. The patients were aged 14.2 years (a range of 11-15 years). The injury pattern of the medial patellofemoral ligament was analysed, and trochlear dysplasia was evaluated with regard to sulcus angle, trochlear depth and trochlear asymmetry. The control data consisted of MR images from 21 adult patients who were treated for first-time lateral patellar dislocation. RESULTS After patellar dislocation, injury to the medial patellofemoral ligament was found in 90.2% of the children and in 100% of the adult patients. Injury patterns of the medial patellofemoral ligament were similar between the study group and the control group with regard to injury at the patellar attachment site (Type I), to the midsubstance (Type II) and to injury at the femoral origin (Type III) (all p>0.05). Combined lesions (Type IV) were significantly less frequently observed in adults when compared to the study group (p=0.02). The magnitude of trochlear dysplasia was similar in children, adolescents and adults with regard to all three of the measured parameter-values (all p>0.05). In addition, the articular cartilage had a significant effect on the distal femur geometry in both paediatrics and adults. CONCLUSION First, the data from our study indicated that the paediatric medial patellofemoral ligament injury patterns, as seen on MR images, were similar to those in adults. Second, the trochlear groove anatomy and the magnitude of trochlear dysplasia, respectively, did not differ between adults and paediatrics with patellar instability. Thus, physicians are confronted with similar anatomical risk factors and similar injuries to the medial soft-tissue restraints in children when compared to adults with patellar instability.

How do spinal segments move

PURPOSE To study and clarify the kinematics of spinal segments following cyclic torques causing axial rotation (T(z) (t)), lateral-flexion (T(x) (t)), flexion/extension (T(y) (t)). METHODS A 6D--Measurement of location, alignment, and migration of the instantaneous helical axis (IHA) as a function of rotational angle in cervical, thoracic, and lumbar segments subjected to axially directed preloads. RESULTS IHA retained an almost constant alignment, but migrated along distinct centrodes. THORACIC SEGMENTS: IHA was almost parallel to T(z) (t), T(x) (t), or T(y) (t), stationary for T(x) (t) or T(y) (t), and migrating for T(z) (t) along dorsally opened bows. IHA locations hardly depended on the position or size of axial preload. LUMBAR SEGMENTS: IHA was also almost parallel to T(z) (t), T(x) (t), or T(y) (t). In axial rotation IHA-migration along wide, ventrally or dorsally bent bows depending on segmental flexional/extensional status. Distances covered: 20-60mm. In lateral-flexion: IHA-migration to the left/right joint and vice versa. In flexion/extension IHA-migration from the facets to the centre of the disc. CERVICAL SEGMENTS: In flexion/flexion IHA was almost stationary for and parallel to T(y) (t). In axial rotation or lateral-flexion IHA intersected T(z) (t)/T(x) (t) under approximately -30 degrees /+30 degrees. CONCLUSIONS Generally joints alternate in guidance. Lumbar segments: in axial rotation and lateral-flexion parametrical control of IHA-position and IHA-migration by axial preload position. Cervical segments: kinematical coupling between axial rotation and lateral-flexion. The IHA-migration guided by the joints should be taken into account in the design of non-fusion implants. FE-calculations of spinal mechanics and kinematics should be based on detailed data of curvature morphology of the articulating surfaces of the joint facets.

Radiologically Hyperdense Zones of the Patella Seem to Be Partial Osteonecroses Subsequent to Fracture Treatment

The blood supply to the proximal patella is provided primarily via intraosseous vessels from the inferior patella. Two vascular systems within the patella are distinguished: Tiny arteries penetrate the middle third of the anterior patellar surface via vascular foramina and continue in a proximal direction. Additional vessels enter the patella at its distal pole, between the patellar ligament and the articular surface, and also run proximally. As a result of the double vascular supply to the distal portion and the vulnerable blood supply to the proximal part, localized osteonecroses subsequent to fracture may occur within the patella and nearly exclusively affect the upper portion of the patella. Such focal regions of osteonecrosis may appear radiographically as localized regions of hyperdensity within the patella. The aim of this study was to investigate the extent to which radiologically hyperdense areas, possibly representing localized osteonecrosis, may occur subsequent to surgical treatment of a patella fracture and the influence that they have on the outcome of the fracture. Retrospective analysis of 100 patients who had been treated operatively for a patella fracture from January 1998 to December 2008 was conducted. The subjective pain rating, clinical scores, and patient satisfaction scores were recorded. Existing X-rays were assessed with regard to possible increased radiological dense areas. After an average of 60.61 ( ± 33.88) months, it was possible to perform a clinical follow-up on 60 patients aged 45.48 ( ± 18.51) years. Radiographic follow-up of all patients revealed that nine patients (9%) exhibited a hyperdense area in the proximal patella portion. X-rays showed radiopaque areas between 1 and 2 months after surgery. In seven cases, the radiological finding disappeared after six months. In two patients with persisting radiologically dense areas, bone necrosis was verified by means of magnetic resonance imaging (MRI) examination and a histological assessment, respectively. The clinical outcome of these patients with a hyperdense area on the patella, in this small series, was not shown to be worse than those who demonstrated normal healing. Radiologically hyperdense areas subsequent to patella fracture may represent partial osteonecrosis caused by localized vascular compromise. This was confirmed by MRI and histological examinations in two patients with persistent hyperdense lesions. The clinical outcome of patients with hyperdense zones seems to be poorer than that of patients without such findings, but no statistical difference was shown in this small series. It is possible that earlier surgical treatment and thus a shorter ischemic period as well as tissue-conserving operative techniques could prevent the occurrence of partial necroses. This hypothesis would require further study.

Navigated Cementless Total Knee Arthroplasty - Medium-Term Clinical and Radiological Results

Purpose: The objective of this prospective study was to evaluate the medium-term clinical and radiological results after navigated cementless implantation, without patella resurfacing, of a total knee endoprosthesis with tibial and femoral press-fit components, with a focus on survival rate and clinical outcome. The innovation is the non-cemented fixation together with the use of a navigation system. Scope and Methods: Sixty patients with gonarthrosis were included consecutively in this study. In all cases, the cementless Columbus total knee endoprosthesis with a coating out of pure titanium was implanted, using a navigation system. The Knee Society Score showed a statistically significant increase from 75 (± 21.26) before surgery to 180 (± 16.15) after a mean follow-up of 5.6 (± 0.25) years. The last radiological examination revealed no osteolysis. No radiolucent lines were seen at any time in the area of the femoral prosthetic components. In the tibial area, radiolucent lines were seen in 24.4 % of the cases, mostly in the distal uncoated part of the stem. During follow-up, no prosthesis had to be replaced because of aseptic loosening while in 2 cases revision surgery was necessary due to septic loosening and in 1 case due to unexplainable pain. Results and Conclusions: Navigated cementless implantation of the Columbus total knee endoprosthesis yielded good clinical and radiological results in the medium term. The excellent radiological osteointegration of the prosthetic components, coated with a microporous pure titanium layer and implanted with a press-fit technique, should be emphasized.

The morphology of the articular surfaces of biological knee joints provides essential guidance for the construction of functional knee endoprostheses

PURPOSE In comparative examinations of kinematics of the knees of humans and pigs in flexional/extensional motion under compressive loads, the significant differential geometric essentials of articular guidance are elaborated to criticise the shaping of the articular surfaces of conventional knee-endoprostheses and to suggest constructional outlines that allow the endoprosthesis to adopt natural knee kinematics. Implantation is discussed with regard to the remaining ligamentous apparatus. METHODS Twelve fresh pig knee joints and 19 preserved human knee joints were moved into several flexional/extensional positions. In each joint, the tibia and femur were repeatably caught by metal plates. After removing all ligaments, the tibia and femur were again caught in these positions, and their points of contact were marked on both articular surfaces. Along the marker points, a thin lead wire was glued onto each surface. The positions and shapes of the four contact lines were mapped by teleradiography. RESULTS All contact lines were found to be plane curves. The medial and lateral planes were parallel, thus defining the joints sagittal plane. In the human knee, as compared to the lateral, the medial femoral contact line was always shifted anteriorly by several millimetres. The tibial contact curve was laterally convex and medially concave. In the pig knees, the lateral and medial contact lines were asymmetrically placed. Both tibial curves were convex. CONCLUSIONS Both knees represent cam mechanisms (with one degree of freedom) that produce rolling of the articular surfaces during the stance phase. Implantation requires preservation of the anterior cruciate ligament, and ligamentous balancing is disadvantageous.

Characteristics of femorotibial joint geometry in the trochlear dysplastic femur

The medial and lateral tibia plateau geometry has been linked with the severity of trochlear dysplasia. The aim of the present study was to evaluate the tibial slope and the femoral posterior condylar offset in a cohort of consecutive subjects with a trochlear dysplastic femur to investigate whether the condylar offset correlates with, and thus potentially compensates for, tibial slope asymmetry. Magnetic resonance imaging was used to assess the severity of trochlear dysplasia as well as the tibial slope and posterior offset of the femoral condyles separately for the medial and lateral compartment of the knee joint in 98 subjects with a trochlear dysplastic femur and 88 control subjects. A significant positive correlation was found for the medial tibial slope and the medial posterior condylar offset in the study group (r2 = 0.1566; P < 0.001). This relationship was significant for all subtypes of trochlear dysplasia and was most pronounced in the severe trochlear dysplastic femur (Dejour type D) (r2 = 0.3734; P = 0.04). No correlation was found for the lateral condylar offset and the lateral tibial slope in the study group or for the condylar offset and the tibial slope on both sides in the control group. The positive correlation between the medial femoral condylar offset and the medial tibial slope, that is, a greater degree of the medial tibial slope indicated a larger offset of the medial femoral condyle, appears to represent a general anthropomorphic characteristic of distal femur geometry in patients with a trochlear dysplastic femur.

Does total disc arthroplasty in C3/C4-segments change the kinematic features of axial rotation?

We analyze how kinematic properties of C3/C4-segments are modified after total disc arthroplasty (TDA) with PRESTIGE(®) and BRYAN(®) Cervical Discs. The measurements were focused on small ranges of axial rotation (<0.8°) in order to investigate physiologic rotations, which frequently occur in vivo. Eight human segments were stimulated by triangularly varying, axially directed torque. By using a 6D-measuring device with high resolution the response of segmental motion was characterised by the instantaneous helical axis (IHA). Position, direction, and migration rate of the IHA were measured before and after TDA. External parameters: constant axially directed pre-load, constant flexional/extensional and lateral-flexional pre-torque. The applied axial torque and IHA-direction did not run parallel. The IHA-direction was found to be rotated backwards and largely independent of the rotational angle, amount of axial pre-load, size of pre-torque, and TDA. In the intact segments pre-flexion/extension hardly influenced IHA-positions. After TDA, IHA-position was shifted backwards significantly (BRYAN-TDA: ≈8mm; PRESTIGE-TDA: ≈6mm) and in some segments laterally as well. Furthermore it was significantly shifted ventrally by pre-flexion and dorsally by pre-extension. The rate of lateral IHA-migration increased significantly after BRYAN-TDA during rightward or leftward rotations. In conclusion after the TDA the IHA-positions shifted backwards with significant increase in variability of the IHA-positions after the BRYAN-TDA more than in PRESTIGE-TDA. The TDA-procedure altered the segment kinematics considerably. TDA causes additional translations of the vertebrae, which superimpose the kinematics of the adjacent levels. The occurrence of adjacent level disease (ALD) is not excluded after the TDA for kinematical reasons.

A minimally invasive dorsal approach to the medial femoral condyle as a donor site for osteochondral transfer procedures

ZusammenfassungOperationszielDauerhafte Wiederherstellung der Gelenkfläche durch Transplantation autologer osteochondraler Zylinder. Entnahme der Zylinder aus der dorsalen medialen Femurkondyle über einen minimalinvasiven Zugang.IndikationenDritt- und viertgradige Knorpelschäden (nach ICRS [International Cartilage Repair Society]), osteochondrale Läsionen oder Osteochondrosis dissecans.KontraindikationenZweit- oder höhergradige Knorpelschäden an der dorsalen medialen Femurkondyle, Infekt, Achsabweichungen von mehr als 5° in der Frontalebene, fortgeschrittene Gonarthrose.OperationstechnikEntnahme der Zylinder zunächst an der Empfängerstelle, Festlegen von Anzahl und Durchmesser der zu entnehmenden Zylinder. Anschließend Bauchlage, Hautschnitt über der dorsalen medialen Femurkondyle. Nach Durchtrennung der oberflächlichen Faszie Weghalten der Semitendinosussehne und des medialen Gastroknemiuskopfs nach lateral, Arthrotomie, Einsetzen von zwei Hohmann- Haken medial und lateral der Femurkondyle und Entnahme der Spenderzylinder mit einer Hohlstanze oder -fräse. Vorteile des beschriebenen Zugangs: Weichteilschonend, einfache Operationstechnik, zusätzliche Entnahmemöglichkeit für osteochondrale Zylinder neben Trochlea femoris und interkondylärer Notch, geringe Entnahmemorbidität.WeiterbehandlungTeilbelastung von 10–20 kg für 4–6 Wochen. Limitierung der Kniebeugung auf 90° für 6 Wochen.ErgebnisseVon 01/2006 bis 04/2007 wurde bei 16 Patienten die dorsale mediale Femurkondyle als Spenderregion für die Transplantation autologer osteochondraler Zylinder verwendet. Sowohl präoperativ als auch zur Nachuntersuchung wurde der Knee Society Score (KSS), der Western Ontario and McMaster Universities (WOMAC) Score, der Tegner-Score sowie die visuelle Analogskala (VAS) Schmerz erhoben. Alle Patienten konnten nach durchschnittlich 13,9 (±4,3) Monaten nachuntersucht werden. Die durchschnittliche Defektfläche betrug 4,6 (±2,2) cm2. Die verwendeten Scores zeigten beim Vergleich der präoperativen Werte mit denen bei der Nachuntersuchung deutliche Besserungen: KSS 123,1 (±41,5) versus 171,3 (±16,9) Punkte (p < 0,05), Tegner-Score 2,8 (±0,9) versus 3,4 (±0,6) Punkte (p < 0,05) und WOMAC-Score 73,3 (±50,2) versus 26,1 (±17,6) Punkte (p < 0,05). Die VAS Schmerz reduzierte sich von 5,3 (±2,7) auf 2,4 (±1,8) Punkte (p < 0,05).Ein Patient mit einem Defekt von 8 cm2 an der medialen Kondyle (Morbus Ahlbäck) klagte bei tiefer Kniebeuge 1 Jahr postoperativ noch über Beschwerden.Die dorsale mediale Femurkondyle ist als Donorregion für die Transplantation autologer osteochondraler Zylinder geeignet. Insbesondere hat sich der minimalinvasive Zugang als sicher und komplikationsarm bewährt.AbstractObjectiveLong-lasting reconstruction of joint surface by using an osteochondral transfer procedure (OCT). Reduction of donor site morbidity by using a minimally invasive approach to the dorsal medial femoral condyle.IndicationsGrade 3 and 4 cartilage lesions (according to ICRS [International Cartilage Repair Society]), osteochondral lesions, and osteochondrosis dissecans.ContraindicationsGrade 2 or higher-graded cartilage lesions at the dorsal medial femoral condyle, infection, axis deviation of more than 5° in the frontal plane, advanced osteoarthritis.Surgical TechniqueCylinders at recipient site are removed first, thereby determining number and diameter of donor cylinders. Supine position, skin incision over the dorsal medial femoral condyle. After dissection of soft tissue and superficial fascia, semitendinosus tendon and medial gastrocnemius muscle are retracted to the lateral side, followed by arthrotomy, introduction of two Hohmann retractors medial and lateral of the condyle, and harvesting of the donor cylinders with a tubular chisel.Advantages of the described approach: reduction of soft-tissue trauma, easy surgical technique, additional donor site area besides femoral trochlea and intercondylar notch.Postoperative ManagementPartial weight bearing of 10–20 kg for 4–6 weeks. Limitation of knee flexion to 90° for 6 weeks.ResultsBetween 01/2006 and 04/2007, the dorsal medial femoral condyle was used as a donor site in 16 patients. All patients were evaluated preoperatively and after 1 year using the American Knee Society Score (KSS), the Western Ontario and McMaster Universities (WOMAC) Score, the Tegner Score, and the visual analog scale (VAS) pain. The mean follow- up was 13.9 (±4.3) months. The mean defect area was 4.6 (±2.2) cm2.The mean KSS, Tegner Score, and WOMAC Score improved from 123.1 (±41.5), 2.8 (±0.9), and 73.3 (±50.2) points preoperatively to 171.3 (±16.9), 3.4 (±0.6), and 26.1 (±17.6) points after 13.9 months (p < 0.05). The VAS pain improved from 5.3 (±2.7) to 2.4 (±1.8) points (p < 0.05).One patient with an osteochondral defect of 8 cm2 at the medial femoral condyle (Ahlbäck’s disease) still complains of pain during deep squatting.The dorsal medial femoral condyle can be recommended as donor site for OCT. The minimally invasive approach has proven to be safe and simple with a low complication rate.

Physiologically shaped knee arthroplasty induces natural roll-back

After total knee replacement the persistence of pain represents a significant problem. In this study, a novel knee arthroplasty (Aequos G1 knee arthroplasty) is investigated that was designed to replicate main features of human knee morphology to reduce the periodically occurring pain after knee replacement. Previous work showed theoretically that this arthroplasty design may reconstruct the four-bar linkage mechanism as it occurs in human knee by contriving a convex lateral tibial compartment and a sagittal offset of the centre of the medial and lateral femur condyles - inducing a roll-back mechanism as it exists in human. The aim of this study was to determine whether this potential roll-back mechanism can be confirmed by in-vivo measurements. This retrospective study showed that the patellar tendon angle decreases during flexion of 0.21° per degree of flexion on average in the 16 knees studied. This amount is similar to physiological knee kinematics and in contrast to existing results in the literature after implantation of conventional total knee replacements which lack physiological knee kinematics. The results suggest that physiological motion after implantation of the Aequos G1 knee arthroplasty occurs during loaded motion up to approximately 45° knee flexion.

Entnahme osteochondraler Zylinder aus der medialen dorsalen Femurkondyle über einen minimalinvasiven Zugang

ZusammenfassungOperationszielDauerhafte Wiederherstellung der Gelenkfläche durch Transplantation autologer osteochondraler Zylinder. Entnahme der Zylinder aus der dorsalen medialen Femurkondyle über einen minimalinvasiven Zugang.IndikationenDritt- und viertgradige Knorpelschäden (nach ICRS [International Cartilage Repair Society]), osteochondrale Läsionen oder Osteochondrosis dissecans.KontraindikationenZweit- oder höhergradige Knorpelschäden an der dorsalen medialen Femurkondyle, Infekt, Achsabweichungen von mehr als 5° in der Frontalebene, fortgeschrittene Gonarthrose.OperationstechnikEntnahme der Zylinder zunächst an der Empfängerstelle, Festlegen von Anzahl und Durchmesser der zu entnehmenden Zylinder. Anschließend Bauchlage, Hautschnitt über der dorsalen medialen Femurkondyle. Nach Durchtrennung der oberflächlichen Faszie Weghalten der Semitendinosussehne und des medialen Gastroknemiuskopfs nach lateral, Arthrotomie, Einsetzen von zwei Hohmann- Haken medial und lateral der Femurkondyle und Entnahme der Spenderzylinder mit einer Hohlstanze oder -fräse. Vorteile des beschriebenen Zugangs: Weichteilschonend, einfache Operationstechnik, zusätzliche Entnahmemöglichkeit für osteochondrale Zylinder neben Trochlea femoris und interkondylärer Notch, geringe Entnahmemorbidität.WeiterbehandlungTeilbelastung von 10–20 kg für 4–6 Wochen. Limitierung der Kniebeugung auf 90° für 6 Wochen.ErgebnisseVon 01/2006 bis 04/2007 wurde bei 16 Patienten die dorsale mediale Femurkondyle als Spenderregion für die Transplantation autologer osteochondraler Zylinder verwendet. Sowohl präoperativ als auch zur Nachuntersuchung wurde der Knee Society Score (KSS), der Western Ontario and McMaster Universities (WOMAC) Score, der Tegner-Score sowie die visuelle Analogskala (VAS) Schmerz erhoben. Alle Patienten konnten nach durchschnittlich 13,9 (±4,3) Monaten nachuntersucht werden. Die durchschnittliche Defektfläche betrug 4,6 (±2,2) cm2. Die verwendeten Scores zeigten beim Vergleich der präoperativen Werte mit denen bei der Nachuntersuchung deutliche Besserungen: KSS 123,1 (±41,5) versus 171,3 (±16,9) Punkte (p < 0,05), Tegner-Score 2,8 (±0,9) versus 3,4 (±0,6) Punkte (p < 0,05) und WOMAC-Score 73,3 (±50,2) versus 26,1 (±17,6) Punkte (p < 0,05). Die VAS Schmerz reduzierte sich von 5,3 (±2,7) auf 2,4 (±1,8) Punkte (p < 0,05).Ein Patient mit einem Defekt von 8 cm2 an der medialen Kondyle (Morbus Ahlbäck) klagte bei tiefer Kniebeuge 1 Jahr postoperativ noch über Beschwerden.Die dorsale mediale Femurkondyle ist als Donorregion für die Transplantation autologer osteochondraler Zylinder geeignet. Insbesondere hat sich der minimalinvasive Zugang als sicher und komplikationsarm bewährt.AbstractObjectiveLong-lasting reconstruction of joint surface by using an osteochondral transfer procedure (OCT). Reduction of donor site morbidity by using a minimally invasive approach to the dorsal medial femoral condyle.IndicationsGrade 3 and 4 cartilage lesions (according to ICRS [International Cartilage Repair Society]), osteochondral lesions, and osteochondrosis dissecans.ContraindicationsGrade 2 or higher-graded cartilage lesions at the dorsal medial femoral condyle, infection, axis deviation of more than 5° in the frontal plane, advanced osteoarthritis.Surgical TechniqueCylinders at recipient site are removed first, thereby determining number and diameter of donor cylinders. Supine position, skin incision over the dorsal medial femoral condyle. After dissection of soft tissue and superficial fascia, semitendinosus tendon and medial gastrocnemius muscle are retracted to the lateral side, followed by arthrotomy, introduction of two Hohmann retractors medial and lateral of the condyle, and harvesting of the donor cylinders with a tubular chisel.Advantages of the described approach: reduction of soft-tissue trauma, easy surgical technique, additional donor site area besides femoral trochlea and intercondylar notch.Postoperative ManagementPartial weight bearing of 10–20 kg for 4–6 weeks. Limitation of knee flexion to 90° for 6 weeks.ResultsBetween 01/2006 and 04/2007, the dorsal medial femoral condyle was used as a donor site in 16 patients. All patients were evaluated preoperatively and after 1 year using the American Knee Society Score (KSS), the Western Ontario and McMaster Universities (WOMAC) Score, the Tegner Score, and the visual analog scale (VAS) pain. The mean follow- up was 13.9 (±4.3) months. The mean defect area was 4.6 (±2.2) cm2.The mean KSS, Tegner Score, and WOMAC Score improved from 123.1 (±41.5), 2.8 (±0.9), and 73.3 (±50.2) points preoperatively to 171.3 (±16.9), 3.4 (±0.6), and 26.1 (±17.6) points after 13.9 months (p < 0.05). The VAS pain improved from 5.3 (±2.7) to 2.4 (±1.8) points (p < 0.05).One patient with an osteochondral defect of 8 cm2 at the medial femoral condyle (Ahlbäck’s disease) still complains of pain during deep squatting.The dorsal medial femoral condyle can be recommended as donor site for OCT. The minimally invasive approach has proven to be safe and simple with a low complication rate.