[Running and causes of running-related injuries].

Running is one of the most popular sports among the adult Danish population. Overuse injuries of the knee, such as runners knee, jumpers knee, patello-femoral pain syndrome and patello-femoral pre-arthrosis, are common and cause reduction of the health beneficial physical activity. Treatment should primarily focus on adjustment of training habits and physiotherapeutic guided rehabilitation. Other treatment options include changing landing pattern during running, corticosteroid injections, non-steroid anti-inflammatory drugs and ultimately surgery.

High eccentric hip abduction strength reduces the risk of developing patellofemoral pain among novice runners initiating a self-structured running program: a 1-year observational study.

STUDY DESIGN: Observational prospective cohort study with 1-year follow-up. OBJECTIVES: To investigate the relationship between eccentric hip abduction strength and the development of patellofemoral pain (PFP) in novice runners during a self-structured running regime. BACKGROUND: Recent research indicates that gluteal muscle weakness exists in individuals with PFP. However, current prospective research has been limited to the evaluation of isometric strength, producing inconsistent findings. Considering that hip muscles, including the gluteus maximus and medius, activate eccentrically to control hip and pelvic motion during weight-bearing activities such as running, the potential link between eccentric strength and PFP risk should be evaluated. METHODS: Eight hundred thirty-two novice runners were included at baseline, and 629 participants were included in the final analysis. Maximal eccentric hip abduction strength was measured using a handheld dynamometer prior to initiating a self-structured running program. The diagnostic criteria to classify knee pain as PFP were based on a thorough clinical examination. Participants were followed for 12 months and training characteristics were gathered with a global positioning system. RESULTS: Results from the unadjusted generalized linear regression model for cumulative risk at 25 and 50 km indicated differences in cumulative risk of PFP between high strength, normal strength, and low strength (P<.05), with higher strength associated with reduced risk. CONCLUSION: Findings from this study indicate that, among novice runners, a level of peak eccentric hip abduction strength that is higher than normal may reduce the risk of PFP during the first 50 km of a self-structured running program.

[Denervation of the patella: influence on mid-term results after total knee arthroplasty]. / Retropatellare Denervierung : Einfluss auf die mittelfristigen Ergebnisse von Knietotalendoprothesenimplantationen.

BACKGROUND: The purpose of the study was to determine possible differences in the mid-term results of total knee arthroplasty in patients treated with and without denervation of the patella. PATIENTS AND METHODS: This study included 80 total knee replacements in 71 patients who were treated with total knee replacement, either with (n = 40) or without (n = 40) simultaneous denervation of the patella out of a total population with 122 knee replacements in 100 patients. Comparability of both groups was achieved by applying matching criteria. All patients were reviewed by isokinetic tests, physical and radiological examination. The mean follow-up time was 2.2 years. RESULTS: The mean hospital for special surgery (HSS) score revealed no statistically significant differences between both groups (with denervation 77.9 ± 11.1 and without denervation 77.8 ± 11.0, p = 0.976). The isokinetic torque measurements with low angle velocity (60°/s) indicated slightly higher values during extension (60.2 ± 32.2 Nm versus 55.8 ± 25.2 Nm, p = 0.497) and flexion (52.4 ± 28.3 Nm versus 46.1 ± 22.3 Nm, p = 0.272) movements of the affected knee joint. However, the differences did not reach statistical significance. At high angle velocity (180°/s) no differences could be found between both groups. No cases of postoperative necrosis of the patella were observed. Anterior knee pain after denervation was reported in 6 cases (15 %) compared to 10 cases (25 %) in patients who were treated without denervation (p = 0.402). CONCLUSION: No statistically significant differences could be found between patients with and without denervation of the patella for total knee arthroplasty.

No difference in anterior knee pain between a fixed and a mobile posterior stabilized total knee arthroplasty after 7.9 years.

PURPOSE: The presence of anterior knee pain remains one of the major complaints following total knee arthroplasty (TKA). Since the introduction of the mobile TKA, many studies have been performed and only a few show a slight advantage for the mobile. In our short-term follow-up study, we found less anterior knee pain in the posterior stabilized mobile knees compared to the posterior stabilized knees. The concept of self-alignment and the results from our short-term study led us to form the hypothesis that the posterior stabilized mobile knee leads to a lower incidence of anterior knee pain compared to the posterior stabilized fixed knee. This study was designed to see whether this difference remains after 7.9 years in the follow-up. A secondary line of enquiry was to see whether one was superior to the other regarding pain, function, quality of life and survival. METHODS: This current report is a 6-10-year (median 7.9 years) follow-up study of the remaining 69 patients with a cemented three-component TKA for osteoarthritis in a prospective, randomized, double-blinded clinical trial. RESULTS: In the posterior stabilized group, five of the 40 knees (13%) versus five of the 29 posterior stabilized mobile group (17%) experienced anterior knee pain. No differences were observed with regard to ROM, VAS, Oxford 12-item knee questionnaire, SF-36, HSS patella, Kujala or the AKSS score. Patients with anterior knee pain reported more pain, lower levels of the AKSS, HSS patella and the Kujala scores than the patients without anterior knee pain. CONCLUSION: In the current clinical practice, the appearance of anterior knee pain persists as a problem; simply changing to a mobile bearing does not seem to be the solution. The posterior stabilized mobile total knee did not sustain the advantage of less anterior knee pain, compared with the posterior stabilized fixed total knee arthroplasty. LEVEL OF EVIDENCE: Therapeutic study, Level II.

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.

Less anterior knee pain with a routine lateral release in total knee arthroplasty without patellar resurfacing: a prospective, randomized study.

PURPOSE: Anterior knee pain is a major cause of complaint in total knee arthroplasty (TKA) without patellar resurfacing. The concept of improved patellar tracking and decreased retropatellar contact pressure for lateral retinacular release theoretically suggests that patients with lateral retinacular release in TKA would achieve a lower incidence of anterior knee pain when compared without lateral retinacular release. We sought to determine (1) whether those patients who received a routine lateral retinacular release in TKA would attain lower incidence of anterior knee pain as compared to patients who received TKA without lateral retinacular release and (2) whether lateral retinacular release would increase the lateral retinacular release-related complications. METHODS: A total of 148 patients who underwent TKA with the use of the Gemini MK II mobile bearing were randomized to receive either routine lateral retinacular release (intervention group) or not (control group). Patients were assessed by the visual analogue scale for anterior knee pain, the Knee Society clinical scoring system of knee score and function score, and patellar score for clinical function. Patients' satisfaction and lateral retinacular release-related complications were also evaluated. RESULTS: The overall incidence of anterior knee pain in the intervention group at 18 months follow-up was 5.6%, while that of the control group was 20.6% (p = 0.009). No statistical difference was detected between the two groups in terms of lateral retinacular release-related complications (n.s.), patients' satisfaction (n.s.), knee score (n.s.), function score (n.s.), and patellar score (n.s.) at 18 months follow-up. CONCLUSION: The present study suggests that routine lateral retinacular release can reduce anterior knee pain and does not increase lateral retinacular release-related complications, in TKA with the use of the Gemini MK II mobile bearing without patellar resurfacing. LEVEL OF EVIDENCE: Therapeutic, Level I.

Análise cinemática do joelho ao subir e descer escada na instabilidade patelofemoral / Kinematic analisys of the knee when climbing up/down stairs in patellofemoral instability

OBJETIVO: Analisar e identificar possíveis adaptações da marcha em indivíduos com diagnóstico de instabilidade patelofemoral objetiva, durante a atividade de subida e descida de escada. MÉTODOS: Foram analisados um grupo controle (grupo A), composto por 9 mulheres com média de idade de 25 anos (±1,87), média de altura de 1,62m (±0,05) e média de peso de 56,20kg (±7,34); e, um grupo de 9 mulheres com instabilidade patelofemoral objetiva (grupo B), média de idade de 24 anos (±6,02), média de altura de 1,62m (±0,06) e média de peso de 60,33kg (±10,31). Os grupos foram submetidos a uma análise cinemática, onde as voluntárias subiram e desceram degraus, em uma área previamente selecionada. As imagens foram obtidas por seis câmeras (Qualysis) e a análise dos dados foi realizada através do programa Q gait. RESULTADOS: O grupo B apresentou, no período de apoio, menor flexão do joelho durante a subida (p=0,0268), além de menores velocidade (p=0,0076/ p=0,0243) e cadência (p=0,0027/ p=0,0165) na subida e na descida, respectivamente. CONCLUSÃO: Sugere-se que o grupo B utilizou adaptações funcionais como redução da flexão do joelho, da velocidade e da cadência, durante a subida e a descida de degraus.

OBJECTIVE: To analyze and to identify possible gait adaptations by individuals with objective patellofemoral instability when climbing up/down stairs. METHODS: A control group (group A) composed by nine women with mean age = 25 years (±1.87), height = 1.62 m (±0.05) and weight = 56.20 kg (±7.34), and; nine women with objective patellofemoral instability (group B) with mean age = 24 years (±6.02), height = 1.62 m (±0.06) and weight = 60.33 kg (±10.31) were analyzed. The groups underwent kinematic analysis while climbing up/down stairs, in a previously determined area. Images were obtained by six cameras (Qualysis) and data analysis utilized the Q gait software program. RESULTS: Group B presented, in the support phase, less knee flexion when climbing up (p = 0.0268), and lower speed (p = 0.0076/ p =0.0243) and pace (p = 0.0027/ p = 0.0165) when climbing up and down stairs, respectively. CONCLUSION: It is suggested that group B used functional changes such as reduced knee flexion, speed and pace when climbing up and down stairs.

Effect of bracing on the prevention of anterior knee pain--a prospective randomized study.

There have been numerous reports about the use of knee braces to prevent traumatic knee injuries. Despite the frequent use of braces, very few prospective studies have been performed to study the effect of knee braces for preventing anterior knee pain syndrome (AKPS). The purpose of this study was to assess the effectiveness of a dynamic patellofemoral brace (On-Track System, dj Orthopedics) in the prevention of AKPS. 167 military recruits without history of knee pain were randomized into two groups prior to the start of their 6-week basic military training (BMT) program. The first group (brace group) consisted of 54 recruits who wore the braces for all physical activities during these 6 weeks. 113 recruits served as a control group, and followed the same 6-week strenuous training program. Chi square statistics (Fisher exact test) were used to compare the number of AKPS patients in the brace group and in the non-brace group. Our results indicated that recruits in the brace group appeared to develop significantly less anterior knee pain compared to the recruits in the control group (p=0.020). Out of the 54 recruits in the brace group, ten (18.5%) developed anterior knee pain during this study. In the control group (n=113), 42 recruits (37%) developed anterior knee pain. We conclude that the result of the present study suggests that the use of a dynamic patellofemoral brace is an effective way to prevent the development of anterior knee pain in persons undergoing a strenuous training program.